PeerStreamer

@chapter Audio Filters

@c man begin AUDIO FILTERS

When you configure your FFmpeg build, you can disable any of the

existing filters using --disable-filters.

The configure output will show the audio filters included in your

build.

Below is a description of the currently available audio filters.

@section anull

Pass the audio source unchanged to the output.

@c man end AUDIO FILTERS

@chapter Video Filters

@c man begin VIDEO FILTERS

When you configure your FFmpeg build, you can disable any of the

existing filters using --disable-filters.

The configure output will show the video filters included in your

build.

Below is a description of the currently available video filters.

@section crop

Crop the input video to @var{width}:@var{height}:@var{x}:@var{y}.

@example

./ffmpeg -i in.avi -vf "crop=0:240:0:0" out.avi

@end example

The @var{width} and @var{height} parameters specify the width and height

of the output (non-cropped) area.

A value of 0 is interpreted as the maximum possible size contained in

the area delimited by the top-left corner at position x:y.

@var{x} and @var{y} specify the position of the top-left corner of the

output (non-cropped) area.

The default value of @var{x} and @var{y} is 0.

For example the parameters:

@example

"crop=0:0:100:100"

@end example

will delimit the rectangle with the top-left corner placed at position

100:100 and the right-bottom corner corresponding to the right-bottom

corner of the input image.

The default value of @var{width} and @var{height} is 0.

@section fifo

Buffer input images and send them when they are requested.

This filter is mainly useful when auto-inserted by the libavfilter

framework.

The filter does not take parameters.

@section format

Convert the input video to one of the specified pixel formats.

Libavfilter will try to pick one that is supported for the input to

the next filter.

The filter accepts a list of pixel format names, separated by ":",

for example "yuv420p:monow:rgb24".

The following command:

@example

./ffmpeg -i in.avi -vf "format=yuv420p" out.avi

@end example

will convert the input video to the format "yuv420p".

@section frei0r

Apply a frei0r effect to the input video.

To enable compilation of this filter you need to install the frei0r

header and configure FFmpeg with --enable-frei0r.

The filter supports the syntax:

@example

@var{filter_name}:@var{param1}:@var{param2}:...:@var{paramN}

@end example

@var{filter_name} is the name to the frei0r effect to load. If the

environment variable @env{FREI0R_PATH} is defined, the frei0r effect

is searched in each one of the directories specified by the colon

separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r

paths, which are in this order: @file{HOME/.frei0r-1/lib/},

@file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.

@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters

for the frei0r effect.

A frei0r effect parameter can be a boolean (whose values are specified

with "y" and "n"), a double, a color (specified by the syntax

@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float

numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color

description), a position (specified by the syntax @var{X}/@var{Y},

@var{X} and @var{Y} being float numbers) and a string.

The number and kind of parameters depend on the loaded effect. If an

effect parameter is not specified the default value is set.

Some examples follow:

@example

# apply the distort0r effect, set the first two double parameters

frei0r=distort0r:0.5:0.01

# apply the colordistance effect, takes a color as first parameter

frei0r=colordistance:0.2/0.3/0.4

frei0r=colordistance:violet

frei0r=colordistance:0x112233

# apply the perspective effect, specify the top left and top right

# image positions

frei0r=perspective:0.2/0.2:0.8/0.2

@end example

For more information see:

@url{http://piksel.org/frei0r}

@section hflip

Flip the input video horizontally.

For example to horizontally flip the video in input with

@file{ffmpeg}:

@example

ffmpeg -i in.avi -vf "hflip" out.avi

@end example

@section noformat

Force libavfilter not to use any of the specified pixel formats for the

input to the next filter.

The filter accepts a list of pixel format names, separated by ":",

for example "yuv420p:monow:rgb24".

The following command:

@example

./ffmpeg -i in.avi -vf "noformat=yuv420p, vflip" out.avi

@end example

will make libavfilter use a format different from "yuv420p" for the

input to the vflip filter.

@section null

Pass the video source unchanged to the output.

@section ocv_smooth

Apply smooth transform using libopencv.

To enable this filter install libopencv library and headers and

configure FFmpeg with --enable-libopencv.

The filter accepts the following parameters:

@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.

@var{type} is the type of smooth filter to apply, and can be one of

the following values: "blur", "blur_no_scale", "median", "gaussian",

"bilateral". The default value is "gaussian".

@var{param1}, @var{param2}, @var{param3}, and @var{param4} are

parameters whose meanings depend on smooth type. @var{param1} and

@var{param2} accept integer positive values or 0, @var{param3} and

@var{param4} accept float values.

The default value for @var{param1} is 3, the default value for the

other parameters is 0.

These parameters correspond to the parameters assigned to the

libopencv function @code{cvSmooth}. Refer to the official libopencv

documentation for the exact meaning of the parameters:

@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}

@section pad

Add paddings to the input image, and places the original input at the

given coordinates @var{x}, @var{y}.

It accepts the following parameters:

@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.

Follows the description of the accepted parameters.

@table @option

@item width, height

Specify the size of the output image with the paddings added. If the

value for @var{width} or @var{height} is 0, the corresponding input size

is used for the output.

The default value of @var{width} and @var{height} is 0.

@item x, y

Specify the offsets where to place the input image in the padded area

with respect to the top/left border of the output image.

The default value of @var{x} and @var{y} is 0.

@item color

Specify the color of the padded area, it can be the name of a color

(case insensitive match) or a 0xRRGGBB[AA] sequence.

The default value of @var{color} is "black".

@end table

@section pixdesctest

Pixel format descriptor test filter, mainly useful for internal

testing. The output video should be equal to the input video.

For example:

@example

format=monow, pixdesctest

@end example

can be used to test the monowhite pixel format descriptor definition.

@section scale

Scale the input video to @var{width}:@var{height} and/or convert the image format.

For example the command:

@example

./ffmpeg -i in.avi -vf "scale=200:100" out.avi

@end example

will scale the input video to a size of 200x100.

If the input image format is different from the format requested by

the next filter, the scale filter will convert the input to the

requested format.

If the value for @var{width} or @var{height} is 0, the respective input

size is used for the output.

If the value for @var{width} or @var{height} is -1, the scale filter will

use, for the respective output size, a value that maintains the aspect

ratio of the input image.

The default value of @var{width} and @var{height} is 0.

@section slicify

Pass the images of input video on to next video filter as multiple

slices.

@example

./ffmpeg -i in.avi -vf "slicify=32" out.avi

@end example

The filter accepts the slice height as parameter. If the parameter is

not specified it will use the default value of 16.

Adding this in the beginning of filter chains should make filtering

faster due to better use of the memory cache.

@section unsharp

Sharpen or blur the input video.

It accepts the following parameters:

@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}

Negative values for the amount will blur the input video, while positive

values will sharpen. All parameters are optional and default to the

equivalent of the string '5:5:1.0:0:0:0.0'.

@table @option

@item luma_msize_x

Set the luma matrix horizontal size. It can be an integer between 3

and 13, default value is 5.

@item luma_msize_y

Set the luma matrix vertical size. It can be an integer between 3

and 13, default value is 5.

@item luma_amount

Set the luma effect strength. It can be a float number between -2.0

and 5.0, default value is 1.0.

@item chroma_msize_x

Set the chroma matrix horizontal size. It can be an integer between 3

and 13, default value is 0.

@item chroma_msize_y

Set the chroma matrix vertical size. It can be an integer between 3

and 13, default value is 0.

@item luma_amount

Set the chroma effect strength. It can be a float number between -2.0

and 5.0, default value is 0.0.

@end table

@example

# Strong luma sharpen effect parameters

unsharp=7:7:2.5

# Strong blur of both luma and chroma parameters

unsharp=7:7:-2:7:7:-2

# Use the default values with @command{ffmpeg}

./ffmpeg -i in.avi -vf "unsharp" out.mp4

@end example

@section vflip

Flip the input video vertically.

@example

./ffmpeg -i in.avi -vf "vflip" out.avi

@end example

@c man end VIDEO FILTERS

@chapter Video Sources

@c man begin VIDEO SOURCES

Below is a description of the currently available video sources.

@section buffer

Buffer video frames, and make them available to the filter chain.

This source is mainly intended for a programmatic use, in particular

through the interface defined in @file{libavfilter/vsrc_buffer.h}.

It accepts the following parameters:

@var{width}:@var{height}:@var{pix_fmt_string}

All the parameters need to be explicitely defined.

Follows the list of the accepted parameters.

@table @option

@item width, height

Specify the width and height of the buffered video frames.

@item pix_fmt_string

A string representing the pixel format of the buffered video frames.

It may be a number corresponding to a pixel format, or a pixel format

name.

@end table

For example:

@example

buffer=320:240:yuv410p

@end example

will instruct the source to accept video frames with size 320x240 and

with format "yuv410p". Since the pixel format with name "yuv410p"

corresponds to the number 6 (check the enum PixelFormat definition in

@file{libavutil/pixfmt.h}), this example corresponds to:

@example

buffer=320:240:6

@end example

@section color

Provide an uniformly colored input.

It accepts the following parameters:

@var{color}:@var{frame_size}:@var{frame_rate}

Follows the description of the accepted parameters.

@table @option

@item color

Specify the color of the source. It can be the name of a color (case

insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an

alpha specifier. The default value is "black".

@item frame_size

Specify the size of the sourced video, it may be a string of the form

@var{width}x@var{heigth}, or the name of a size abbreviation. The

default value is "320x240".

@item frame_rate

Specify the frame rate of the sourced video, as the number of frames

generated per second. It has to be a string in the format

@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float

number or a valid video frame rate abbreviation. The default value is

"25".

@end table

For example the following graph description will generate a red source

with an opacity of 0.2, with size "qcif" and a frame rate of 10

frames per second, which will be overlayed over the source connected

to the pad with identifier "in".

@example

"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"

@end example

@section nullsrc

Null video source, never return images. It is mainly useful as a

template and to be employed in analysis / debugging tools.

It accepts as optional parameter a string of the form

@var{width}:@var{height}, where @var{width} and @var{height} specify the size of

the configured source.

The default values of @var{width} and @var{height} are respectively 352

and 288 (corresponding to the CIF size format).

@c man end VIDEO SOURCES

@chapter Video Sinks

@c man begin VIDEO SINKS

Below is a description of the currently available video sinks.

@section nullsink

Null video sink, do absolutely nothing with the input video. It is

mainly useful as a template and to be employed in analysis / debugging

tools.

@c man end VIDEO SINKS