Apply misc fixes to the image2 muxer documentation.
[libav.git] / doc / muxers.texi
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1@chapter Muxers
2@c man begin MUXERS
3
4Muxers are configured elements in FFmpeg which allow writing
5multimedia streams to a particular type of file.
6
7When you configure your FFmpeg build, all the supported muxers
8are enabled by default. You can list all available muxers using the
9configure option @code{--list-muxers}.
10
11You can disable all the muxers with the configure option
12@code{--disable-muxers} and selectively enable / disable single muxers
13with the options @code{--enable-muxer=@var{MUXER}} /
14@code{--disable-muxer=@var{MUXER}}.
15
16The option @code{-formats} of the ff* tools will display the list of
17enabled muxers.
18
19A description of some of the currently available muxers follows.
20
77d4ed7a 21@anchor{crc}
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22@section crc
23
24CRC (Cyclic Redundancy Check) testing format.
25
26This muxer computes and prints the Adler-32 CRC of all the input audio
27and video frames. By default audio frames are converted to signed
2816-bit raw audio and video frames to raw video before computing the
29CRC.
30
31The output of the muxer consists of a single line of the form:
32CRC=0x@var{CRC}, where @var{CRC} is a hexadecimal number 0-padded to
338 digits containing the CRC for all the decoded input frames.
34
35For example to compute the CRC of the input, and store it in the file
36@file{out.crc}:
37@example
38ffmpeg -i INPUT -f crc out.crc
39@end example
40
41You can print the CRC to stdout with the command:
42@example
43ffmpeg -i INPUT -f crc -
44@end example
45
46You can select the output format of each frame with @file{ffmpeg} by
47specifying the audio and video codec and format. For example to
48compute the CRC of the input audio converted to PCM unsigned 8-bit
49and the input video converted to MPEG-2 video, use the command:
50@example
51ffmpeg -i INPUT -acodec pcm_u8 -vcodec mpeg2video -f crc -
52@end example
53
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54See also the @code{framecrc} muxer (@pxref{framecrc}).
55
56@anchor{framecrc}
57@section framecrc
58
59Per-frame CRC (Cyclic Redundancy Check) testing format.
60
61This muxer computes and prints the Adler-32 CRC for each decoded audio
62and video frame. By default audio frames are converted to signed
6316-bit raw audio and video frames to raw video before computing the
64CRC.
65
66The output of the muxer consists of a line for each audio and video
67frame of the form: @var{stream_index}, @var{frame_dts},
68@var{frame_size}, 0x@var{CRC}, where @var{CRC} is a hexadecimal
69number 0-padded to 8 digits containing the CRC of the decoded frame.
70
71For example to compute the CRC of each decoded frame in the input, and
72store it in the file @file{out.crc}:
73@example
74ffmpeg -i INPUT -f framecrc out.crc
75@end example
76
77You can print the CRC of each decoded frame to stdout with the command:
78@example
79ffmpeg -i INPUT -f framecrc -
80@end example
81
82You can select the output format of each frame with @file{ffmpeg} by
83specifying the audio and video codec and format. For example, to
84compute the CRC of each decoded input audio frame converted to PCM
85unsigned 8-bit and of each decoded input video frame converted to
86MPEG-2 video, use the command:
87@example
88ffmpeg -i INPUT -acodec pcm_u8 -vcodec mpeg2video -f framecrc -
89@end example
90
91See also the @code{crc} muxer (@pxref{crc}).
92
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93@section image2
94
95Image file muxer.
96
0cad24ce 97The image file muxer writes video frames to image files.
e771d2e3 98
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99The output filenames are specified by a pattern, which can be used to
100produce sequentially numbered series of files.
101The pattern may contain the string "%d" or "%0@var{N}d", this string
e771d2e3 102specifies the position of the characters representing a numbering in
0cad24ce 103the filenames. If the form "%0@var{N}d" is used, the string
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104representing the number in each filename is 0-padded to @var{N}
105digits. The literal character '%' can be specified in the pattern with
106the string "%%".
107
108If the pattern contains "%d" or "%0@var{N}d", the first filename of
109the file list specified will contain the number 1, all the following
110numbers will be sequential.
111
112The pattern may contain a suffix which is used to automatically
113determine the format of the image files to write.
114
115For example the pattern "img-%03d.bmp" will specify a sequence of
116filenames of the form @file{img-001.bmp}, @file{img-002.bmp}, ...,
117@file{img-010.bmp}, etc.
118The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
119form @file{img%-1.jpg}, @file{img%-2.jpg}, ..., @file{img%-10.jpg},
120etc.
121
122The following example shows how to use @file{ffmpeg} for creating a
123sequence of files @file{img-001.jpeg}, @file{img-002.jpeg}, ...,
124taking one image every second from the input video:
125@example
126ffmpeg -i in.avi -r 1 -f image2 'img-%03d.jpeg'
127@end example
128
129Note that with @file{ffmpeg}, if the format is not specified with the
130@code{-f} option and the output filename specifies an image file
131format, the image2 muxer is automatically selected, so the previous
132command can be written as:
133@example
134ffmpeg -i in.avi -r 1 'img-%03d.jpeg'
135@end example
136
137Note 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
141ffmpeg -i in.avi -f image2 -vframes 1 img.jpeg
142@end example
143
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144@section mpegts
145
146MPEG transport stream muxer.
147
148This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
149
150The muxer options are:
151
152@table @option
153@item -mpegts_original_network_id @var{number}
154Set the original_network_id (default 0x0001). This is unique identifier
155of a network in DVB. Its main use is in the unique identification of a
156service through the path Original_Network_ID, Transport_Stream_ID.
157@item -mpegts_transport_stream_id @var{number}
158Set the transport_stream_id (default 0x0001). This identifies a
159transponder in DVB.
160@item -mpegts_service_id @var{number}
161Set the service_id (default 0x0001) also known as program in DVB.
162@item -mpegts_pmt_start_pid @var{number}
163Set the first PID for PMT (default 0x1000, max 0x1f00).
164@item -mpegts_start_pid @var{number}
165Set the first PID for data packets (default 0x0100, max 0x0f00).
166@end table
167
168The recognized metadata settings in mpegts muxer are @code{service_provider}
169and @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
174ffmpeg -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
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185@section null
186
187Null muxer.
188
189This muxer does not generate any output file, it is mainly useful for
190testing or benchmarking purposes.
191
192For example to benchmark decoding with @file{ffmpeg} you can use the
193command:
194@example
195ffmpeg -benchmark -i INPUT -f null out.null
196@end example
197
198Note that the above command does not read or write the @file{out.null}
199file, but specifying the output file is required by the @file{ffmpeg}
200syntax.
201
202Alternatively you can write the command as:
203@example
204ffmpeg -benchmark -i INPUT -f null -
205@end example
206
85466e1e 207@c man end MUXERS