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@chapter Filtergraph description |
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@c man begin FILTERGRAPH DESCRIPTION |
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|
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A filtergraph is a directed graph of connected filters. It can contain |
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cycles, and there can be multiple links between a pair of |
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filters. Each link has one input pad on one side connecting it to one |
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filter from which it takes its input, and one output pad on the other |
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side connecting it to the one filter accepting its output. |
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|
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Each filter in a filtergraph is an instance of a filter class |
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registered in the application, which defines the features and the |
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number of input and output pads of the filter. |
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|
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A filter with no input pads is called a "source", a filter with no |
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output pads is called a "sink". |
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|
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@section Filtergraph syntax |
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|
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A filtergraph can be represented using a textual representation, which |
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is recognized by the @code{-vf} and @code{-af} options of the ff* |
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tools, and by the @code{av_parse_graph()} function defined in |
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@file{libavfilter/avfiltergraph}. |
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|
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A filterchain consists of a sequence of connected filters, each one |
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connected to the previous one in the sequence. A filterchain is |
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represented by a list of ","-separated filter descriptions. |
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|
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A filtergraph consists of a sequence of filterchains. A sequence of |
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filterchains is represented by a list of ";"-separated filterchain |
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descriptions. |
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|
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A filter is represented by a string of the form: |
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[@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}] |
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|
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@var{filter_name} is the name of the filter class of which the |
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described filter is an instance of, and has to be the name of one of |
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the filter classes registered in the program. |
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The name of the filter class is optionally followed by a string |
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"=@var{arguments}". |
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|
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@var{arguments} is a string which contains the parameters used to |
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initialize the filter instance, and are described in the filter |
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descriptions below. |
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|
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The list of arguments can be quoted using the character "'" as initial |
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and ending mark, and the character '\' for escaping the characters |
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within the quoted text; otherwise the argument string is considered |
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terminated when the next special character (belonging to the set |
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"[]=;,") is encountered. |
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|
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The name and arguments of the filter are optionally preceded and |
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followed by a list of link labels. |
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A link label allows to name a link and associate it to a filter output |
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or input pad. The preceding labels @var{in_link_1} |
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... @var{in_link_N}, are associated to the filter input pads, |
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the following labels @var{out_link_1} ... @var{out_link_M}, are |
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associated to the output pads. |
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|
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When two link labels with the same name are found in the |
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filtergraph, a link between the corresponding input and output pad is |
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created. |
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|
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If an output pad is not labelled, it is linked by default to the first |
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unlabelled input pad of the next filter in the filterchain. |
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For example in the filterchain: |
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@example |
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nullsrc, split[L1], [L2]overlay, nullsink |
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@end example |
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the split filter instance has two output pads, and the overlay filter |
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instance two input pads. The first output pad of split is labelled |
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"L1", the first input pad of overlay is labelled "L2", and the second |
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output pad of split is linked to the second input pad of overlay, |
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which are both unlabelled. |
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|
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In a complete filterchain all the unlabelled filter input and output |
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pads must be connected. A filtergraph is considered valid if all the |
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filter input and output pads of all the filterchains are connected. |
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|
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Follows a BNF description for the filtergraph syntax: |
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@example |
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@var{NAME} ::= sequence of alphanumeric characters and '_' |
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@var{LINKLABEL} ::= "[" @var{NAME} "]" |
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@var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}] |
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@var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted) |
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@var{FILTER} ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}] |
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@var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}] |
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@var{FILTERGRAPH} ::= @var{FILTERCHAIN} [;@var{FILTERGRAPH}] |
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@end example |
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|
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@c man end FILTERGRAPH DESCRIPTION |
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|
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@chapter Audio Filters |
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@c man begin AUDIO FILTERS |
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|
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When you configure your Libav build, you can disable any of the |
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existing filters using --disable-filters. |
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The configure output will show the audio filters included in your |
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build. |
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|
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Below is a description of the currently available audio filters. |
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|
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@section anull |
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|
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Pass the audio source unchanged to the output. |
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|
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@c man end AUDIO FILTERS |
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|
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@chapter Audio Sources |
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@c man begin AUDIO SOURCES |
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|
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Below is a description of the currently available audio sources. |
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|
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@section anullsrc |
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|
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Null audio source, never return audio frames. It is mainly useful as a |
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template and to be employed in analysis / debugging tools. |
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|
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It accepts as optional parameter a string of the form |
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@var{sample_rate}:@var{channel_layout}. |
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|
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@var{sample_rate} specify the sample rate, and defaults to 44100. |
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|
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@var{channel_layout} specify the channel layout, and can be either an |
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integer or a string representing a channel layout. The default value |
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of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO. |
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|
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Check the channel_layout_map definition in |
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@file{libavcodec/audioconvert.c} for the mapping between strings and |
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channel layout values. |
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|
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Follow some examples: |
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@example |
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# set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO. |
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anullsrc=48000:4 |
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|
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# same as |
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anullsrc=48000:mono |
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@end example |
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|
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@c man end AUDIO SOURCES |
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|
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@chapter Audio Sinks |
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@c man begin AUDIO SINKS |
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|
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Below is a description of the currently available audio sinks. |
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|
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@section anullsink |
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|
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Null audio sink, do absolutely nothing with the input audio. It is |
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mainly useful as a template and to be employed in analysis / debugging |
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tools. |
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|
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@c man end AUDIO SINKS |
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|
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@chapter Video Filters |
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@c man begin VIDEO FILTERS |
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|
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When you configure your Libav build, you can disable any of the |
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existing filters using --disable-filters. |
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The configure output will show the video filters included in your |
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build. |
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|
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Below is a description of the currently available video filters. |
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|
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@section blackframe |
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|
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Detect frames that are (almost) completely black. Can be useful to |
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detect chapter transitions or commercials. Output lines consist of |
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the frame number of the detected frame, the percentage of blackness, |
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the position in the file if known or -1 and the timestamp in seconds. |
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|
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In order to display the output lines, you need to set the loglevel at |
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least to the AV_LOG_INFO value. |
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|
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The filter accepts the syntax: |
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@example |
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blackframe[=@var{amount}:[@var{threshold}]] |
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@end example |
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|
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@var{amount} is the percentage of the pixels that have to be below the |
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threshold, and defaults to 98. |
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|
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@var{threshold} is the threshold below which a pixel value is |
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considered black, and defaults to 32. |
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|
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@section copy |
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|
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Copy the input source unchanged to the output. Mainly useful for |
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testing purposes. |
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|
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@section crop |
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|
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Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}. |
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|
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The parameters are expressions containing the following constants: |
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|
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@table @option |
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@item E, PI, PHI |
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the corresponding mathematical approximated values for e |
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(euler number), pi (greek PI), PHI (golden ratio) |
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|
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@item x, y |
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the computed values for @var{x} and @var{y}. They are evaluated for |
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each new frame. |
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|
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@item in_w, in_h |
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the input width and heigth |
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|
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@item iw, ih |
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same as @var{in_w} and @var{in_h} |
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|
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@item out_w, out_h |
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the output (cropped) width and heigth |
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|
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@item ow, oh |
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same as @var{out_w} and @var{out_h} |
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|
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@item n |
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the number of input frame, starting from 0 |
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|
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@item pos |
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the position in the file of the input frame, NAN if unknown |
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|
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@item t |
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timestamp expressed in seconds, NAN if the input timestamp is unknown |
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|
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@end table |
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|
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The @var{out_w} and @var{out_h} parameters specify the expressions for |
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the width and height of the output (cropped) video. They are |
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evaluated just at the configuration of the filter. |
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|
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The default value of @var{out_w} is "in_w", and the default value of |
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@var{out_h} is "in_h". |
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|
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The expression for @var{out_w} may depend on the value of @var{out_h}, |
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and the expression for @var{out_h} may depend on @var{out_w}, but they |
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cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are |
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evaluated after @var{out_w} and @var{out_h}. |
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|
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The @var{x} and @var{y} parameters specify the expressions for the |
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position of the top-left corner of the output (non-cropped) area. They |
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are evaluated for each frame. If the evaluated value is not valid, it |
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is approximated to the nearest valid value. |
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|
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The default value of @var{x} is "(in_w-out_w)/2", and the default |
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value for @var{y} is "(in_h-out_h)/2", which set the cropped area at |
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the center of the input image. |
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|
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The expression for @var{x} may depend on @var{y}, and the expression |
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for @var{y} may depend on @var{x}. |
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|
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Follow some examples: |
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@example |
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# crop the central input area with size 100x100 |
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crop=100:100 |
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|
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# crop the central input area with size 2/3 of the input video |
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"crop=2/3*in_w:2/3*in_h" |
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|
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# crop the input video central square |
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crop=in_h |
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|
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# delimit the rectangle with the top-left corner placed at position |
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# 100:100 and the right-bottom corner corresponding to the right-bottom |
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# corner of the input image. |
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crop=in_w-100:in_h-100:100:100 |
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|
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# crop 10 pixels from the left and right borders, and 20 pixels from |
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# the top and bottom borders |
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"crop=in_w-2*10:in_h-2*20" |
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|
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# keep only the bottom right quarter of the input image |
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"crop=in_w/2:in_h/2:in_w/2:in_h/2" |
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|
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# crop height for getting Greek harmony |
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"crop=in_w:1/PHI*in_w" |
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|
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# trembling effect |
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"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)" |
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|
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# erratic camera effect depending on timestamp |
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"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)" |
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|
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# set x depending on the value of y |
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"crop=in_w/2:in_h/2:y:10+10*sin(n/10)" |
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@end example |
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|
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@section cropdetect |
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|
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Auto-detect crop size. |
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|
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Calculate necessary cropping parameters and prints the recommended |
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parameters through the logging system. The detected dimensions |
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correspond to the non-black area of the input video. |
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|
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It accepts the syntax: |
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@example |
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cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]] |
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@end example |
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|
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@table @option |
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|
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@item limit |
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Threshold, which can be optionally specified from nothing (0) to |
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everything (255), defaults to 24. |
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|
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@item round |
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Value which the width/height should be divisible by, defaults to |
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16. The offset is automatically adjusted to center the video. Use 2 to |
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get only even dimensions (needed for 4:2:2 video). 16 is best when |
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encoding to most video codecs. |
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|
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@item reset |
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Counter that determines after how many frames cropdetect will reset |
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the previously detected largest video area and start over to detect |
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the current optimal crop area. Defaults to 0. |
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|
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This can be useful when channel logos distort the video area. 0 |
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indicates never reset and return the largest area encountered during |
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playback. |
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@end table |
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|
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@section drawbox |
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|
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Draw a colored box on the input image. |
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|
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It accepts the syntax: |
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@example |
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drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color} |
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@end example |
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|
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@table @option |
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|
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@item x, y |
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Specify the top left corner coordinates of the box. Default to 0. |
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|
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@item width, height |
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Specify the width and height of the box, if 0 they are interpreted as |
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the input width and height. Default to 0. |
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|
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@item color |
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Specify the color of the box to write, it can be the name of a color |
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(case insensitive match) or a 0xRRGGBB[AA] sequence. |
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@end table |
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|
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Follow some examples: |
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@example |
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# draw a black box around the edge of the input image |
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drawbox |
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|
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# draw a box with color red and an opacity of 50% |
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drawbox=10:20:200:60:red@@0.5" |
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@end example |
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|
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@section fade |
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|
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Apply fade-in/out effect to input video. |
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|
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It accepts the parameters: |
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@var{type}:@var{start_frame}:@var{nb_frames} |
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|
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@var{type} specifies if the effect type, can be either "in" for |
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fade-in, or "out" for a fade-out effect. |
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|
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@var{start_frame} specifies the number of the start frame for starting |
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to apply the fade effect. |
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|
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@var{nb_frames} specifies the number of frames for which the fade |
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effect has to last. At the end of the fade-in effect the output video |
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will have the same intensity as the input video, at the end of the |
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fade-out transition the output video will be completely black. |
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|
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A few usage examples follow, usable too as test scenarios. |
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@example |
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# fade in first 30 frames of video |
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fade=in:0:30 |
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|
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# fade out last 45 frames of a 200-frame video |
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fade=out:155:45 |
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|
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# fade in first 25 frames and fade out last 25 frames of a 1000-frame video |
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fade=in:0:25, fade=out:975:25 |
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|
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# make first 5 frames black, then fade in from frame 5-24 |
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fade=in:5:20 |
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@end example |
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|
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@section fifo |
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|
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Buffer input images and send them when they are requested. |
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|
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This filter is mainly useful when auto-inserted by the libavfilter |
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framework. |
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|
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The filter does not take parameters. |
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|
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@section format |
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|
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Convert the input video to one of the specified pixel formats. |
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Libavfilter will try to pick one that is supported for the input to |
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the next filter. |
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|
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The filter accepts a list of pixel format names, separated by ":", |
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for example "yuv420p:monow:rgb24". |
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|
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Some examples follow: |
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@example |
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# convert the input video to the format "yuv420p" |
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format=yuv420p |
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|
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# convert the input video to any of the formats in the list |
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format=yuv420p:yuv444p:yuv410p |
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@end example |
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|
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@anchor{frei0r} |
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@section frei0r |
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|
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Apply a frei0r effect to the input video. |
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|
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To enable compilation of this filter you need to install the frei0r |
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header and configure Libav with --enable-frei0r. |
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|
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The filter supports the syntax: |
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@example |
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@var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}] |
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@end example |
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|
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@var{filter_name} is the name to the frei0r effect to load. If the |
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environment variable @env{FREI0R_PATH} is defined, the frei0r effect |
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is searched in each one of the directories specified by the colon |
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separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r |
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paths, which are in this order: @file{HOME/.frei0r-1/lib/}, |
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@file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}. |
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|
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@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters |
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for the frei0r effect. |
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|
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A frei0r effect parameter can be a boolean (whose values are specified |
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with "y" and "n"), a double, a color (specified by the syntax |
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@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float |
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numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color |
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description), a position (specified by the syntax @var{X}/@var{Y}, |
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@var{X} and @var{Y} being float numbers) and a string. |
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|
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The number and kind of parameters depend on the loaded effect. If an |
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effect parameter is not specified the default value is set. |
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|
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Some examples follow: |
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@example |
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# apply the distort0r effect, set the first two double parameters |
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frei0r=distort0r:0.5:0.01 |
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|
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# apply the colordistance effect, takes a color as first parameter |
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frei0r=colordistance:0.2/0.3/0.4 |
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frei0r=colordistance:violet |
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frei0r=colordistance:0x112233 |
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|
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# apply the perspective effect, specify the top left and top right |
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# image positions |
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frei0r=perspective:0.2/0.2:0.8/0.2 |
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@end example |
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|
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For more information see: |
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@url{http://piksel.org/frei0r} |
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|
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@section gradfun |
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|
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Fix the banding artifacts that are sometimes introduced into nearly flat |
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regions by truncation to 8bit colordepth. |
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Interpolate the gradients that should go where the bands are, and |
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dither them. |
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|
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This filter is designed for playback only. Do not use it prior to |
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lossy compression, because compression tends to lose the dither and |
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bring back the bands. |
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|
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The filter takes two optional parameters, separated by ':': |
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@var{strength}:@var{radius} |
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|
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@var{strength} is the maximum amount by which the filter will change |
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any one pixel. Also the threshold for detecting nearly flat |
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regions. Acceptable values range from .51 to 255, default value is |
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1.2, out-of-range values will be clipped to the valid range. |
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|
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@var{radius} is the neighborhood to fit the gradient to. A larger |
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radius makes for smoother gradients, but also prevents the filter from |
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modifying the pixels near detailed regions. Acceptable values are |
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8-32, default value is 16, out-of-range values will be clipped to the |
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valid range. |
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|
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@example |
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# default parameters |
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gradfun=1.2:16 |
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|
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# omitting radius |
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gradfun=1.2 |
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@end example |
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|
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@section hflip |
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|
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Flip the input video horizontally. |
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|
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For example to horizontally flip the video in input with |
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@file{ffmpeg}: |
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@example |
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ffmpeg -i in.avi -vf "hflip" out.avi |
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@end example |
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|
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@section hqdn3d |
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|
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High precision/quality 3d denoise filter. This filter aims to reduce |
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image noise producing smooth images and making still images really |
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still. It should enhance compressibility. |
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|
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It accepts the following optional parameters: |
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@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp} |
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|
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@table @option |
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@item luma_spatial |
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a non-negative float number which specifies spatial luma strength, |
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defaults to 4.0 |
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|
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@item chroma_spatial |
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a non-negative float number which specifies spatial chroma strength, |
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defaults to 3.0*@var{luma_spatial}/4.0 |
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|
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@item luma_tmp |
529 |
a float number which specifies luma temporal strength, defaults to |
530 |
6.0*@var{luma_spatial}/4.0 |
531 |
|
532 |
@item chroma_tmp |
533 |
a float number which specifies chroma temporal strength, defaults to |
534 |
@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial} |
535 |
@end table |
536 |
|
537 |
@section noformat |
538 |
|
539 |
Force libavfilter not to use any of the specified pixel formats for the |
540 |
input to the next filter. |
541 |
|
542 |
The filter accepts a list of pixel format names, separated by ":", |
543 |
for example "yuv420p:monow:rgb24". |
544 |
|
545 |
Some examples follow: |
546 |
@example |
547 |
# force libavfilter to use a format different from "yuv420p" for the |
548 |
# input to the vflip filter |
549 |
noformat=yuv420p,vflip |
550 |
|
551 |
# convert the input video to any of the formats not contained in the list |
552 |
noformat=yuv420p:yuv444p:yuv410p |
553 |
@end example |
554 |
|
555 |
@section null |
556 |
|
557 |
Pass the video source unchanged to the output. |
558 |
|
559 |
@section ocv |
560 |
|
561 |
Apply video transform using libopencv. |
562 |
|
563 |
To enable this filter install libopencv library and headers and |
564 |
configure Libav with --enable-libopencv. |
565 |
|
566 |
The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}. |
567 |
|
568 |
@var{filter_name} is the name of the libopencv filter to apply. |
569 |
|
570 |
@var{filter_params} specifies the parameters to pass to the libopencv |
571 |
filter. If not specified the default values are assumed. |
572 |
|
573 |
Refer to the official libopencv documentation for more precise |
574 |
informations: |
575 |
@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html} |
576 |
|
577 |
Follows the list of supported libopencv filters. |
578 |
|
579 |
@anchor{dilate} |
580 |
@subsection dilate |
581 |
|
582 |
Dilate an image by using a specific structuring element. |
583 |
This filter corresponds to the libopencv function @code{cvDilate}. |
584 |
|
585 |
It accepts the parameters: @var{struct_el}:@var{nb_iterations}. |
586 |
|
587 |
@var{struct_el} represents a structuring element, and has the syntax: |
588 |
@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape} |
589 |
|
590 |
@var{cols} and @var{rows} represent the number of colums and rows of |
591 |
the structuring element, @var{anchor_x} and @var{anchor_y} the anchor |
592 |
point, and @var{shape} the shape for the structuring element, and |
593 |
can be one of the values "rect", "cross", "ellipse", "custom". |
594 |
|
595 |
If the value for @var{shape} is "custom", it must be followed by a |
596 |
string of the form "=@var{filename}". The file with name |
597 |
@var{filename} is assumed to represent a binary image, with each |
598 |
printable character corresponding to a bright pixel. When a custom |
599 |
@var{shape} is used, @var{cols} and @var{rows} are ignored, the number |
600 |
or columns and rows of the read file are assumed instead. |
601 |
|
602 |
The default value for @var{struct_el} is "3x3+0x0/rect". |
603 |
|
604 |
@var{nb_iterations} specifies the number of times the transform is |
605 |
applied to the image, and defaults to 1. |
606 |
|
607 |
Follow some example: |
608 |
@example |
609 |
# use the default values |
610 |
ocv=dilate |
611 |
|
612 |
# dilate using a structuring element with a 5x5 cross, iterate two times |
613 |
ocv=dilate=5x5+2x2/cross:2 |
614 |
|
615 |
# read the shape from the file diamond.shape, iterate two times |
616 |
# the file diamond.shape may contain a pattern of characters like this: |
617 |
# * |
618 |
# *** |
619 |
# ***** |
620 |
# *** |
621 |
# * |
622 |
# the specified cols and rows are ignored (but not the anchor point coordinates) |
623 |
ocv=0x0+2x2/custom=diamond.shape:2 |
624 |
@end example |
625 |
|
626 |
@subsection erode |
627 |
|
628 |
Erode an image by using a specific structuring element. |
629 |
This filter corresponds to the libopencv function @code{cvErode}. |
630 |
|
631 |
The filter accepts the parameters: @var{struct_el}:@var{nb_iterations}, |
632 |
with the same meaning and use of those of the dilate filter |
633 |
(@pxref{dilate}). |
634 |
|
635 |
@subsection smooth |
636 |
|
637 |
Smooth the input video. |
638 |
|
639 |
The filter takes the following parameters: |
640 |
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}. |
641 |
|
642 |
@var{type} is the type of smooth filter to apply, and can be one of |
643 |
the following values: "blur", "blur_no_scale", "median", "gaussian", |
644 |
"bilateral". The default value is "gaussian". |
645 |
|
646 |
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are |
647 |
parameters whose meanings depend on smooth type. @var{param1} and |
648 |
@var{param2} accept integer positive values or 0, @var{param3} and |
649 |
@var{param4} accept float values. |
650 |
|
651 |
The default value for @var{param1} is 3, the default value for the |
652 |
other parameters is 0. |
653 |
|
654 |
These parameters correspond to the parameters assigned to the |
655 |
libopencv function @code{cvSmooth}. |
656 |
|
657 |
@section overlay |
658 |
|
659 |
Overlay one video on top of another. |
660 |
|
661 |
It takes two inputs and one output, the first input is the "main" |
662 |
video on which the second input is overlayed. |
663 |
|
664 |
It accepts the parameters: @var{x}:@var{y}. |
665 |
|
666 |
@var{x} is the x coordinate of the overlayed video on the main video, |
667 |
@var{y} is the y coordinate. The parameters are expressions containing |
668 |
the following parameters: |
669 |
|
670 |
@table @option |
671 |
@item main_w, main_h |
672 |
main input width and height |
673 |
|
674 |
@item W, H |
675 |
same as @var{main_w} and @var{main_h} |
676 |
|
677 |
@item overlay_w, overlay_h |
678 |
overlay input width and height |
679 |
|
680 |
@item w, h |
681 |
same as @var{overlay_w} and @var{overlay_h} |
682 |
@end table |
683 |
|
684 |
Be aware that frames are taken from each input video in timestamp |
685 |
order, hence, if their initial timestamps differ, it is a a good idea |
686 |
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to |
687 |
have them begin in the same zero timestamp, as it does the example for |
688 |
the @var{movie} filter. |
689 |
|
690 |
Follow some examples: |
691 |
@example |
692 |
# draw the overlay at 10 pixels from the bottom right |
693 |
# corner of the main video. |
694 |
overlay=main_w-overlay_w-10:main_h-overlay_h-10 |
695 |
|
696 |
# insert a transparent PNG logo in the bottom left corner of the input |
697 |
movie=logo.png [logo]; |
698 |
[in][logo] overlay=10:main_h-overlay_h-10 [out] |
699 |
|
700 |
# insert 2 different transparent PNG logos (second logo on bottom |
701 |
# right corner): |
702 |
movie=logo1.png [logo1]; |
703 |
movie=logo2.png [logo2]; |
704 |
[in][logo1] overlay=10:H-h-10 [in+logo1]; |
705 |
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out] |
706 |
|
707 |
# add a transparent color layer on top of the main video, |
708 |
# WxH specifies the size of the main input to the overlay filter |
709 |
color=red@.3:WxH [over]; [in][over] overlay [out] |
710 |
@end example |
711 |
|
712 |
You can chain togheter more overlays but the efficiency of such |
713 |
approach is yet to be tested. |
714 |
|
715 |
@section pad |
716 |
|
717 |
Add paddings to the input image, and places the original input at the |
718 |
given coordinates @var{x}, @var{y}. |
719 |
|
720 |
It accepts the following parameters: |
721 |
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}. |
722 |
|
723 |
Follows the description of the accepted parameters. |
724 |
|
725 |
@table @option |
726 |
@item width, height |
727 |
|
728 |
Specify the size of the output image with the paddings added. If the |
729 |
value for @var{width} or @var{height} is 0, the corresponding input size |
730 |
is used for the output. |
731 |
|
732 |
The default value of @var{width} and @var{height} is 0. |
733 |
|
734 |
@item x, y |
735 |
|
736 |
Specify the offsets where to place the input image in the padded area |
737 |
with respect to the top/left border of the output image. |
738 |
|
739 |
The default value of @var{x} and @var{y} is 0. |
740 |
|
741 |
@item color |
742 |
|
743 |
Specify the color of the padded area, it can be the name of a color |
744 |
(case insensitive match) or a 0xRRGGBB[AA] sequence. |
745 |
|
746 |
The default value of @var{color} is "black". |
747 |
|
748 |
@end table |
749 |
|
750 |
For example: |
751 |
|
752 |
@example |
753 |
# Add paddings with color "violet" to the input video. Output video |
754 |
# size is 640x480, the top-left corner of the input video is placed at |
755 |
# column 0, row 40. |
756 |
pad=640:480:0:40:violet |
757 |
@end example |
758 |
|
759 |
@section pixdesctest |
760 |
|
761 |
Pixel format descriptor test filter, mainly useful for internal |
762 |
testing. The output video should be equal to the input video. |
763 |
|
764 |
For example: |
765 |
@example |
766 |
format=monow, pixdesctest |
767 |
@end example |
768 |
|
769 |
can be used to test the monowhite pixel format descriptor definition. |
770 |
|
771 |
@section scale |
772 |
|
773 |
Scale the input video to @var{width}:@var{height} and/or convert the image format. |
774 |
|
775 |
For example the command: |
776 |
|
777 |
@example |
778 |
./ffmpeg -i in.avi -vf "scale=200:100" out.avi |
779 |
@end example |
780 |
|
781 |
will scale the input video to a size of 200x100. |
782 |
|
783 |
If the input image format is different from the format requested by |
784 |
the next filter, the scale filter will convert the input to the |
785 |
requested format. |
786 |
|
787 |
If the value for @var{width} or @var{height} is 0, the respective input |
788 |
size is used for the output. |
789 |
|
790 |
If the value for @var{width} or @var{height} is -1, the scale filter will |
791 |
use, for the respective output size, a value that maintains the aspect |
792 |
ratio of the input image. |
793 |
|
794 |
The default value of @var{width} and @var{height} is 0. |
795 |
|
796 |
@anchor{setdar} |
797 |
@section setdar |
798 |
|
799 |
Set the Display Aspect Ratio for the filter output video. |
800 |
|
801 |
This is done by changing the specified Sample (aka Pixel) Aspect |
802 |
Ratio, according to the following equation: |
803 |
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR} |
804 |
|
805 |
Keep in mind that this filter does not modify the pixel dimensions of |
806 |
the video frame. Also the display aspect ratio set by this filter may |
807 |
be changed by later filters in the filterchain, e.g. in case of |
808 |
scaling or if another "setdar" or a "setsar" filter is applied. |
809 |
|
810 |
The filter accepts a parameter string which represents the wanted |
811 |
display aspect ratio. |
812 |
The parameter can be a floating point number string, or an expression |
813 |
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the |
814 |
numerator and denominator of the aspect ratio. |
815 |
If the parameter is not specified, it is assumed the value "0:1". |
816 |
|
817 |
For example to change the display aspect ratio to 16:9, specify: |
818 |
@example |
819 |
setdar=16:9 |
820 |
# the above is equivalent to |
821 |
setdar=1.77777 |
822 |
@end example |
823 |
|
824 |
See also the "setsar" filter documentation (@pxref{setsar}). |
825 |
|
826 |
@section setpts |
827 |
|
828 |
Change the PTS (presentation timestamp) of the input video frames. |
829 |
|
830 |
Accept in input an expression evaluated through the eval API, which |
831 |
can contain the following constants: |
832 |
|
833 |
@table @option |
834 |
@item PTS |
835 |
the presentation timestamp in input |
836 |
|
837 |
@item PI |
838 |
Greek PI |
839 |
|
840 |
@item PHI |
841 |
golden ratio |
842 |
|
843 |
@item E |
844 |
Euler number |
845 |
|
846 |
@item N |
847 |
the count of the input frame, starting from 0. |
848 |
|
849 |
@item STARTPTS |
850 |
the PTS of the first video frame |
851 |
|
852 |
@item INTERLACED |
853 |
tell if the current frame is interlaced |
854 |
|
855 |
@item POS |
856 |
original position in the file of the frame, or undefined if undefined |
857 |
for the current frame |
858 |
|
859 |
@item PREV_INPTS |
860 |
previous input PTS |
861 |
|
862 |
@item PREV_OUTPTS |
863 |
previous output PTS |
864 |
|
865 |
@end table |
866 |
|
867 |
Some examples follow: |
868 |
|
869 |
@example |
870 |
# start counting PTS from zero |
871 |
setpts=PTS-STARTPTS |
872 |
|
873 |
# fast motion |
874 |
setpts=0.5*PTS |
875 |
|
876 |
# slow motion |
877 |
setpts=2.0*PTS |
878 |
|
879 |
# fixed rate 25 fps |
880 |
setpts=N/(25*TB) |
881 |
|
882 |
# fixed rate 25 fps with some jitter |
883 |
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))' |
884 |
@end example |
885 |
|
886 |
@anchor{setsar} |
887 |
@section setsar |
888 |
|
889 |
Set the Sample (aka Pixel) Aspect Ratio for the filter output video. |
890 |
|
891 |
Note that as a consequence of the application of this filter, the |
892 |
output display aspect ratio will change according to the following |
893 |
equation: |
894 |
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR} |
895 |
|
896 |
Keep in mind that the sample aspect ratio set by this filter may be |
897 |
changed by later filters in the filterchain, e.g. if another "setsar" |
898 |
or a "setdar" filter is applied. |
899 |
|
900 |
The filter accepts a parameter string which represents the wanted |
901 |
sample aspect ratio. |
902 |
The parameter can be a floating point number string, or an expression |
903 |
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the |
904 |
numerator and denominator of the aspect ratio. |
905 |
If the parameter is not specified, it is assumed the value "0:1". |
906 |
|
907 |
For example to change the sample aspect ratio to 10:11, specify: |
908 |
@example |
909 |
setsar=10:11 |
910 |
@end example |
911 |
|
912 |
@section settb |
913 |
|
914 |
Set the timebase to use for the output frames timestamps. |
915 |
It is mainly useful for testing timebase configuration. |
916 |
|
917 |
It accepts in input an arithmetic expression representing a rational. |
918 |
The expression can contain the constants "PI", "E", "PHI", "AVTB" (the |
919 |
default timebase), and "intb" (the input timebase). |
920 |
|
921 |
The default value for the input is "intb". |
922 |
|
923 |
Follow some examples. |
924 |
|
925 |
@example |
926 |
# set the timebase to 1/25 |
927 |
settb=1/25 |
928 |
|
929 |
# set the timebase to 1/10 |
930 |
settb=0.1 |
931 |
|
932 |
#set the timebase to 1001/1000 |
933 |
settb=1+0.001 |
934 |
|
935 |
#set the timebase to 2*intb |
936 |
settb=2*intb |
937 |
|
938 |
#set the default timebase value |
939 |
settb=AVTB |
940 |
@end example |
941 |
|
942 |
@section slicify |
943 |
|
944 |
Pass the images of input video on to next video filter as multiple |
945 |
slices. |
946 |
|
947 |
@example |
948 |
./ffmpeg -i in.avi -vf "slicify=32" out.avi |
949 |
@end example |
950 |
|
951 |
The filter accepts the slice height as parameter. If the parameter is |
952 |
not specified it will use the default value of 16. |
953 |
|
954 |
Adding this in the beginning of filter chains should make filtering |
955 |
faster due to better use of the memory cache. |
956 |
|
957 |
@section transpose |
958 |
|
959 |
Transpose rows with columns in the input video and optionally flip it. |
960 |
|
961 |
It accepts a parameter representing an integer, which can assume the |
962 |
values: |
963 |
|
964 |
@table @samp |
965 |
@item 0 |
966 |
Rotate by 90 degrees counterclockwise and vertically flip (default), that is: |
967 |
@example |
968 |
L.R L.l |
969 |
. . -> . . |
970 |
l.r R.r |
971 |
@end example |
972 |
|
973 |
@item 1 |
974 |
Rotate by 90 degrees clockwise, that is: |
975 |
@example |
976 |
L.R l.L |
977 |
. . -> . . |
978 |
l.r r.R |
979 |
@end example |
980 |
|
981 |
@item 2 |
982 |
Rotate by 90 degrees counterclockwise, that is: |
983 |
@example |
984 |
L.R R.r |
985 |
. . -> . . |
986 |
l.r L.l |
987 |
@end example |
988 |
|
989 |
@item 3 |
990 |
Rotate by 90 degrees clockwise and vertically flip, that is: |
991 |
@example |
992 |
L.R r.R |
993 |
. . -> . . |
994 |
l.r l.L |
995 |
@end example |
996 |
@end table |
997 |
|
998 |
@section unsharp |
999 |
|
1000 |
Sharpen or blur the input video. |
1001 |
|
1002 |
It accepts the following parameters: |
1003 |
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount} |
1004 |
|
1005 |
Negative values for the amount will blur the input video, while positive |
1006 |
values will sharpen. All parameters are optional and default to the |
1007 |
equivalent of the string '5:5:1.0:0:0:0.0'. |
1008 |
|
1009 |
@table @option |
1010 |
|
1011 |
@item luma_msize_x |
1012 |
Set the luma matrix horizontal size. It can be an integer between 3 |
1013 |
and 13, default value is 5. |
1014 |
|
1015 |
@item luma_msize_y |
1016 |
Set the luma matrix vertical size. It can be an integer between 3 |
1017 |
and 13, default value is 5. |
1018 |
|
1019 |
@item luma_amount |
1020 |
Set the luma effect strength. It can be a float number between -2.0 |
1021 |
and 5.0, default value is 1.0. |
1022 |
|
1023 |
@item chroma_msize_x |
1024 |
Set the chroma matrix horizontal size. It can be an integer between 3 |
1025 |
and 13, default value is 0. |
1026 |
|
1027 |
@item chroma_msize_y |
1028 |
Set the chroma matrix vertical size. It can be an integer between 3 |
1029 |
and 13, default value is 0. |
1030 |
|
1031 |
@item luma_amount |
1032 |
Set the chroma effect strength. It can be a float number between -2.0 |
1033 |
and 5.0, default value is 0.0. |
1034 |
|
1035 |
@end table |
1036 |
|
1037 |
@example |
1038 |
# Strong luma sharpen effect parameters |
1039 |
unsharp=7:7:2.5 |
1040 |
|
1041 |
# Strong blur of both luma and chroma parameters |
1042 |
unsharp=7:7:-2:7:7:-2 |
1043 |
|
1044 |
# Use the default values with @command{ffmpeg} |
1045 |
./ffmpeg -i in.avi -vf "unsharp" out.mp4 |
1046 |
@end example |
1047 |
|
1048 |
@section vflip |
1049 |
|
1050 |
Flip the input video vertically. |
1051 |
|
1052 |
@example |
1053 |
./ffmpeg -i in.avi -vf "vflip" out.avi |
1054 |
@end example |
1055 |
|
1056 |
@section yadif |
1057 |
|
1058 |
Deinterlace the input video ("yadif" means "yet another deinterlacing |
1059 |
filter"). |
1060 |
|
1061 |
It accepts the optional parameters: @var{mode}:@var{parity}. |
1062 |
|
1063 |
@var{mode} specifies the interlacing mode to adopt, accepts one of the |
1064 |
following values: |
1065 |
|
1066 |
@table @option |
1067 |
@item 0 |
1068 |
output 1 frame for each frame |
1069 |
@item 1 |
1070 |
output 1 frame for each field |
1071 |
@item 2 |
1072 |
like 0 but skips spatial interlacing check |
1073 |
@item 3 |
1074 |
like 1 but skips spatial interlacing check |
1075 |
@end table |
1076 |
|
1077 |
Default value is 0. |
1078 |
|
1079 |
@var{parity} specifies the picture field parity assumed for the input |
1080 |
interlaced video, accepts one of the following values: |
1081 |
|
1082 |
@table @option |
1083 |
@item 0 |
1084 |
assume bottom field first |
1085 |
@item 1 |
1086 |
assume top field first |
1087 |
@item -1 |
1088 |
enable automatic detection |
1089 |
@end table |
1090 |
|
1091 |
Default value is -1. |
1092 |
If interlacing is unknown or decoder does not export this information, |
1093 |
top field first will be assumed. |
1094 |
|
1095 |
@c man end VIDEO FILTERS |
1096 |
|
1097 |
@chapter Video Sources |
1098 |
@c man begin VIDEO SOURCES |
1099 |
|
1100 |
Below is a description of the currently available video sources. |
1101 |
|
1102 |
@section buffer |
1103 |
|
1104 |
Buffer video frames, and make them available to the filter chain. |
1105 |
|
1106 |
This source is mainly intended for a programmatic use, in particular |
1107 |
through the interface defined in @file{libavfilter/vsrc_buffer.h}. |
1108 |
|
1109 |
It accepts the following parameters: |
1110 |
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den} |
1111 |
|
1112 |
All the parameters need to be explicitely defined. |
1113 |
|
1114 |
Follows the list of the accepted parameters. |
1115 |
|
1116 |
@table @option |
1117 |
|
1118 |
@item width, height |
1119 |
Specify the width and height of the buffered video frames. |
1120 |
|
1121 |
@item pix_fmt_string |
1122 |
A string representing the pixel format of the buffered video frames. |
1123 |
It may be a number corresponding to a pixel format, or a pixel format |
1124 |
name. |
1125 |
|
1126 |
@item timebase_num, timebase_den |
1127 |
Specify numerator and denomitor of the timebase assumed by the |
1128 |
timestamps of the buffered frames. |
1129 |
@end table |
1130 |
|
1131 |
For example: |
1132 |
@example |
1133 |
buffer=320:240:yuv410p:1:24 |
1134 |
@end example |
1135 |
|
1136 |
will instruct the source to accept video frames with size 320x240 and |
1137 |
with format "yuv410p" and assuming 1/24 as the timestamps timebase. |
1138 |
Since the pixel format with name "yuv410p" corresponds to the number 6 |
1139 |
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}), |
1140 |
this example corresponds to: |
1141 |
@example |
1142 |
buffer=320:240:6:1:24 |
1143 |
@end example |
1144 |
|
1145 |
@section color |
1146 |
|
1147 |
Provide an uniformly colored input. |
1148 |
|
1149 |
It accepts the following parameters: |
1150 |
@var{color}:@var{frame_size}:@var{frame_rate} |
1151 |
|
1152 |
Follows the description of the accepted parameters. |
1153 |
|
1154 |
@table @option |
1155 |
|
1156 |
@item color |
1157 |
Specify the color of the source. It can be the name of a color (case |
1158 |
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an |
1159 |
alpha specifier. The default value is "black". |
1160 |
|
1161 |
@item frame_size |
1162 |
Specify the size of the sourced video, it may be a string of the form |
1163 |
@var{width}x@var{heigth}, or the name of a size abbreviation. The |
1164 |
default value is "320x240". |
1165 |
|
1166 |
@item frame_rate |
1167 |
Specify the frame rate of the sourced video, as the number of frames |
1168 |
generated per second. It has to be a string in the format |
1169 |
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float |
1170 |
number or a valid video frame rate abbreviation. The default value is |
1171 |
"25". |
1172 |
|
1173 |
@end table |
1174 |
|
1175 |
For example the following graph description will generate a red source |
1176 |
with an opacity of 0.2, with size "qcif" and a frame rate of 10 |
1177 |
frames per second, which will be overlayed over the source connected |
1178 |
to the pad with identifier "in". |
1179 |
|
1180 |
@example |
1181 |
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]" |
1182 |
@end example |
1183 |
|
1184 |
@section movie |
1185 |
|
1186 |
Read a video stream from a movie container. |
1187 |
|
1188 |
It accepts the syntax: @var{movie_name}[:@var{options}] where |
1189 |
@var{movie_name} is the name of the resource to read (not necessarily |
1190 |
a file but also a device or a stream accessed through some protocol), |
1191 |
and @var{options} is an optional sequence of @var{key}=@var{value} |
1192 |
pairs, separated by ":". |
1193 |
|
1194 |
The description of the accepted options follows. |
1195 |
|
1196 |
@table @option |
1197 |
|
1198 |
@item format_name, f |
1199 |
Specifies the format assumed for the movie to read, and can be either |
1200 |
the name of a container or an input device. If not specified the |
1201 |
format is guessed from @var{movie_name} or by probing. |
1202 |
|
1203 |
@item seek_point, sp |
1204 |
Specifies the seek point in seconds, the frames will be output |
1205 |
starting from this seek point, the parameter is evaluated with |
1206 |
@code{av_strtod} so the numerical value may be suffixed by an IS |
1207 |
postfix. Default value is "0". |
1208 |
|
1209 |
@item stream_index, si |
1210 |
Specifies the index of the video stream to read. If the value is -1, |
1211 |
the best suited video stream will be automatically selected. Default |
1212 |
value is "-1". |
1213 |
|
1214 |
@end table |
1215 |
|
1216 |
This filter allows to overlay a second video on top of main input of |
1217 |
a filtergraph as shown in this graph: |
1218 |
@example |
1219 |
input -----------> deltapts0 --> overlay --> output |
1220 |
^ |
1221 |
| |
1222 |
movie --> scale--> deltapts1 -------+ |
1223 |
@end example |
1224 |
|
1225 |
Some examples follow: |
1226 |
@example |
1227 |
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it |
1228 |
# on top of the input labelled as "in". |
1229 |
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie]; |
1230 |
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out] |
1231 |
|
1232 |
# read from a video4linux2 device, and overlay it on top of the input |
1233 |
# labelled as "in" |
1234 |
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie]; |
1235 |
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out] |
1236 |
|
1237 |
@end example |
1238 |
|
1239 |
@section nullsrc |
1240 |
|
1241 |
Null video source, never return images. It is mainly useful as a |
1242 |
template and to be employed in analysis / debugging tools. |
1243 |
|
1244 |
It accepts as optional parameter a string of the form |
1245 |
@var{width}:@var{height}:@var{timebase}. |
1246 |
|
1247 |
@var{width} and @var{height} specify the size of the configured |
1248 |
source. The default values of @var{width} and @var{height} are |
1249 |
respectively 352 and 288 (corresponding to the CIF size format). |
1250 |
|
1251 |
@var{timebase} specifies an arithmetic expression representing a |
1252 |
timebase. The expression can contain the constants "PI", "E", "PHI", |
1253 |
"AVTB" (the default timebase), and defaults to the value "AVTB". |
1254 |
|
1255 |
@section frei0r_src |
1256 |
|
1257 |
Provide a frei0r source. |
1258 |
|
1259 |
To enable compilation of this filter you need to install the frei0r |
1260 |
header and configure Libav with --enable-frei0r. |
1261 |
|
1262 |
The source supports the syntax: |
1263 |
@example |
1264 |
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}] |
1265 |
@end example |
1266 |
|
1267 |
@var{size} is the size of the video to generate, may be a string of the |
1268 |
form @var{width}x@var{height} or a frame size abbreviation. |
1269 |
@var{rate} is the rate of the video to generate, may be a string of |
1270 |
the form @var{num}/@var{den} or a frame rate abbreviation. |
1271 |
@var{src_name} is the name to the frei0r source to load. For more |
1272 |
information regarding frei0r and how to set the parameters read the |
1273 |
section "frei0r" (@pxref{frei0r}) in the description of the video |
1274 |
filters. |
1275 |
|
1276 |
Some examples follow: |
1277 |
@example |
1278 |
# generate a frei0r partik0l source with size 200x200 and framerate 10 |
1279 |
# which is overlayed on the overlay filter main input |
1280 |
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay |
1281 |
@end example |
1282 |
|
1283 |
@c man end VIDEO SOURCES |
1284 |
|
1285 |
@chapter Video Sinks |
1286 |
@c man begin VIDEO SINKS |
1287 |
|
1288 |
Below is a description of the currently available video sinks. |
1289 |
|
1290 |
@section nullsink |
1291 |
|
1292 |
Null video sink, do absolutely nothing with the input video. It is |
1293 |
mainly useful as a template and to be employed in analysis / debugging |
1294 |
tools. |
1295 |
|
1296 |
@c man end VIDEO SINKS |
1297 |
|