Statistics
| Branch: | Revision:

ffmpeg / doc / muxers.texi @ 0cad24ce

History | View | Annotate | Download (6.88 KB)

1
@chapter Muxers
2
@c man begin MUXERS
3

    
4
Muxers are configured elements in FFmpeg which allow writing
5
multimedia streams to a particular type of file.
6

    
7
When you configure your FFmpeg build, all the supported muxers
8
are enabled by default. You can list all available muxers using the
9
configure option @code{--list-muxers}.
10

    
11
You can disable all the muxers with the configure option
12
@code{--disable-muxers} and selectively enable / disable single muxers
13
with the options @code{--enable-muxer=@var{MUXER}} /
14
@code{--disable-muxer=@var{MUXER}}.
15

    
16
The option @code{-formats} of the ff* tools will display the list of
17
enabled muxers.
18

    
19
A description of some of the currently available muxers follows.
20

    
21
@anchor{crc}
22
@section crc
23

    
24
CRC (Cyclic Redundancy Check) testing format.
25

    
26
This muxer computes and prints the Adler-32 CRC of all the input audio
27
and video frames. By default audio frames are converted to signed
28
16-bit raw audio and video frames to raw video before computing the
29
CRC.
30

    
31
The output of the muxer consists of a single line of the form:
32
CRC=0x@var{CRC}, where @var{CRC} is a hexadecimal number 0-padded to
33
8 digits containing the CRC for all the decoded input frames.
34

    
35
For example to compute the CRC of the input, and store it in the file
36
@file{out.crc}:
37
@example
38
ffmpeg -i INPUT -f crc out.crc
39
@end example
40

    
41
You can print the CRC to stdout with the command:
42
@example
43
ffmpeg -i INPUT -f crc -
44
@end example
45

    
46
You can select the output format of each frame with @file{ffmpeg} by
47
specifying the audio and video codec and format. For example to
48
compute the CRC of the input audio converted to PCM unsigned 8-bit
49
and the input video converted to MPEG-2 video, use the command:
50
@example
51
ffmpeg -i INPUT -acodec pcm_u8 -vcodec mpeg2video -f crc -
52
@end example
53

    
54
See also the @code{framecrc} muxer (@pxref{framecrc}).
55

    
56
@anchor{framecrc}
57
@section framecrc
58

    
59
Per-frame CRC (Cyclic Redundancy Check) testing format.
60

    
61
This muxer computes and prints the Adler-32 CRC for each decoded audio
62
and video frame. By default audio frames are converted to signed
63
16-bit raw audio and video frames to raw video before computing the
64
CRC.
65

    
66
The output of the muxer consists of a line for each audio and video
67
frame of the form: @var{stream_index}, @var{frame_dts},
68
@var{frame_size}, 0x@var{CRC}, where @var{CRC} is a hexadecimal
69
number 0-padded to 8 digits containing the CRC of the decoded frame.
70

    
71
For example to compute the CRC of each decoded frame in the input, and
72
store it in the file @file{out.crc}:
73
@example
74
ffmpeg -i INPUT -f framecrc out.crc
75
@end example
76

    
77
You can print the CRC of each decoded frame to stdout with the command:
78
@example
79
ffmpeg -i INPUT -f framecrc -
80
@end example
81

    
82
You can select the output format of each frame with @file{ffmpeg} by
83
specifying the audio and video codec and format. For example, to
84
compute the CRC of each decoded input audio frame converted to PCM
85
unsigned 8-bit and of each decoded input video frame converted to
86
MPEG-2 video, use the command:
87
@example
88
ffmpeg -i INPUT -acodec pcm_u8 -vcodec mpeg2video -f framecrc -
89
@end example
90

    
91
See also the @code{crc} muxer (@pxref{crc}).
92

    
93
@section image2
94

    
95
Image file muxer.
96

    
97
The image file muxer writes video frames to image files.
98

    
99
The output filenames are specified by a pattern, which can be used to
100
produce sequentially numbered series of files.
101
The pattern may contain the string "%d" or "%0@var{N}d", this string
102
specifies the position of the characters representing a numbering in
103
the filenames. If the form "%0@var{N}d" is used, the string
104
representing the number in each filename is 0-padded to @var{N}
105
digits. The literal character '%' can be specified in the pattern with
106
the string "%%".
107

    
108
If the pattern contains "%d" or "%0@var{N}d", the first filename of
109
the file list specified will contain the number 1, all the following
110
numbers will be sequential.
111

    
112
The pattern may contain a suffix which is used to automatically
113
determine the format of the image files to write.
114

    
115
For example the pattern "img-%03d.bmp" will specify a sequence of
116
filenames of the form @file{img-001.bmp}, @file{img-002.bmp}, ...,
117
@file{img-010.bmp}, etc.
118
The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
119
form @file{img%-1.jpg}, @file{img%-2.jpg}, ..., @file{img%-10.jpg},
120
etc.
121

    
122
The following example shows how to use @file{ffmpeg} for creating a
123
sequence of files @file{img-001.jpeg}, @file{img-002.jpeg}, ...,
124
taking one image every second from the input video:
125
@example
126
ffmpeg -i in.avi -r 1 -f image2 'img-%03d.jpeg'
127
@end example
128

    
129
Note that with @file{ffmpeg}, if the format is not specified with the
130
@code{-f} option and the output filename specifies an image file
131
format, the image2 muxer is automatically selected, so the previous
132
command can be written as:
133
@example
134
ffmpeg -i in.avi -r 1 'img-%03d.jpeg'
135
@end example
136

    
137
Note also that the pattern must not necessarily contain "%d" or
138
"%0@var{N}d", for example to create a single image file
139
@file{img.jpeg} from the input video you can employ the command:
140
@example
141
ffmpeg -i in.avi -f image2 -vframes 1 img.jpeg
142
@end example
143

    
144
@section mpegts
145

    
146
MPEG transport stream muxer.
147

    
148
This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
149

    
150
The muxer options are:
151

    
152
@table @option
153
@item -mpegts_original_network_id @var{number}
154
Set the original_network_id (default 0x0001). This is unique identifier
155
of a network in DVB. Its main use is in the unique identification of a
156
service through the path Original_Network_ID, Transport_Stream_ID.
157
@item -mpegts_transport_stream_id @var{number}
158
Set the transport_stream_id (default 0x0001). This identifies a
159
transponder in DVB.
160
@item -mpegts_service_id @var{number}
161
Set the service_id (default 0x0001) also known as program in DVB.
162
@item -mpegts_pmt_start_pid @var{number}
163
Set the first PID for PMT (default 0x1000, max 0x1f00).
164
@item -mpegts_start_pid @var{number}
165
Set the first PID for data packets (default 0x0100, max 0x0f00).
166
@end table
167

    
168
The recognized metadata settings in mpegts muxer are @code{service_provider}
169
and @code{service_name}. If they are not set the default for
170
@code{service_provider} is "FFmpeg" and the default for
171
@code{service_name} is "Service01".
172

    
173
@example
174
ffmpeg -i file.mpg -acodec copy -vcodec copy \
175
     -mpegts_original_network_id 0x1122 \
176
     -mpegts_transport_stream_id 0x3344 \
177
     -mpegts_service_id 0x5566 \
178
     -mpegts_pmt_start_pid 0x1500 \
179
     -mpegts_start_pid 0x150 \
180
     -metadata service_provider="Some provider" \
181
     -metadata service_name="Some Channel" \
182
     -y out.ts
183
@end example
184

    
185
@section null
186

    
187
Null muxer.
188

    
189
This muxer does not generate any output file, it is mainly useful for
190
testing or benchmarking purposes.
191

    
192
For example to benchmark decoding with @file{ffmpeg} you can use the
193
command:
194
@example
195
ffmpeg -benchmark -i INPUT -f null out.null
196
@end example
197

    
198
Note that the above command does not read or write the @file{out.null}
199
file, but specifying the output file is required by the @file{ffmpeg}
200
syntax.
201

    
202
Alternatively you can write the command as:
203
@example
204
ffmpeg -benchmark -i INPUT -f null -
205
@end example
206

    
207
@c man end MUXERS