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doc/muxers: clarify documentation for the framecrc muxer

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Makes more explicit that framecrc works at the packet level, also prefers
the term "packet" over "frame" when it makes sense.
This commit is contained in:
Stefano Sabatini 2012-04-07 10:44:07 +02:00
parent fd00662d5a
commit 60e4e430db
1 changed files with 17 additions and 11 deletions

28
doc/muxers.texi

@ -56,31 +56,37 @@ See also the @ref{framecrc} muxer.
@anchor{framecrc} @anchor{framecrc}
@section framecrc @section framecrc
Per-frame CRC (Cyclic Redundancy Check) testing format. Per-packet CRC (Cyclic Redundancy Check) testing format.
This muxer computes and prints the Adler-32 CRC for each decoded audio This muxer computes and prints the Adler-32 CRC for each audio
and video frame. By default audio frames are converted to signed and video packet. By default audio frames are converted to signed
16-bit raw audio and video frames to raw video before computing the 16-bit raw audio and video frames to raw video before computing the
CRC. CRC.
The output of the muxer consists of a line for each audio and video The output of the muxer consists of a line for each audio and video
frame of the form: @var{stream_index}, @var{frame_dts}, @var{frame_pts}, @var{frame_duration}, packet of the form:
@var{frame_size}, 0x@var{CRC}, where @var{CRC} is a hexadecimal @example
number 0-padded to 8 digits containing the CRC of the decoded frame. @var{stream_index}, @var{packet_dts}, @var{packet_pts}, @var{packet_duration}, @var{packet_size}, 0x@var{CRC}
@end example
For example to compute the CRC of each decoded frame in the input, and @var{CRC} is a hexadecimal number 0-padded to 8 digits containing the
store it in the file @file{out.crc}: CRC of the packet.
For example to compute the CRC of the audio and video frames in
@file{INPUT}, converted to raw audio and video packets, and store it
in the file @file{out.crc}:
@example @example
ffmpeg -i INPUT -f framecrc out.crc ffmpeg -i INPUT -f framecrc out.crc
@end example @end example
You can print the CRC of each decoded frame to stdout with the command: To print the information to stdout, use the command:
@example @example
ffmpeg -i INPUT -f framecrc - ffmpeg -i INPUT -f framecrc -
@end example @end example
You can select the output format of each frame with @command{ffmpeg} by With @command{ffmpeg}, you can select the output format to which the
specifying the audio and video codec and format. For example, to audio and video frames are encoded before computing the CRC for each
packet by specifying the audio and video codec. For example, to
compute the CRC of each decoded input audio frame converted to PCM compute the CRC of each decoded input audio frame converted to PCM
unsigned 8-bit and of each decoded input video frame converted to unsigned 8-bit and of each decoded input video frame converted to
MPEG-2 video, use the command: MPEG-2 video, use the command: