[FFmpeg-devel] [PATCH] Add documentation for the CRC muxer.

[Måns Rullgård]

Stefano Sabatini <stefano.sabatini-lala at poste.it> writes:

> ---
>  doc/muxers.texi |   33 +++++++++++++++++++++++++++++++++
>  1 files changed, 33 insertions(+), 0 deletions(-)
>
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index 7076959..f097753 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -18,6 +18,39 @@ enabled muxers.
>
>  A description of some of the currently available muxers follows.
>
> + at section crc
> +
> +CRC (Cyclic Redundancy Check) testing format.
> +
> +This muxer computes and prints the CRC of all the input audio and
> +video frames. By default the CRC is computed on the decoded input
> +audio and video frames converted respectively to rawvideo and signed
> +16-bit rawaudio.

Just one problem, which is not your fault: it's not actually a CRC,
but an adler32 checksum.

> +The output of the muxer consists of a single line of the form:
> +CRC=0x at var{CRC}, where @var{CRC} is an hexadecimal number 0-padded to
> +8 digits containing the CRC for all the decoded input frames.
> +
> +For example to compute the CRC of the input, and store it in the file
> + at file{out.crc}:
> + at example
> +ffmpeg -i INPUT -f crc out.crc
> + at end example
> +
> +You can print the CRC to stdout with the command (using the
> + at file{sh} shell syntax):
> + at example
> +ffmpeg -i INPUT -f crc - 2&> /dev/null
> + at end example

That redirection is not standard shell syntax, and I don't think it's
bash either.

> +You can select the output format of each frame with @file{ffmpeg} by
> +specifying the audio and video codec and format. For example to
> +compute the CRC of the input audio converted to PCM unsigned 8-bit
> +and the input video converted to MPEG-2 video, use the command:
> + at example
> +ffmpeg -i INPUT -acodec pcm_u8 -vcodec mpeg2video -f crc -
> + at end example
> +
>  @section image2
>
>  Image file muxer.
> -- 
> 1.7.2.3

-- 
M?ns Rullg?rd
mans at mansr.com