[FFmpeg-devel] [PATCH 1/3] lavf/riffenc: Improve spec compliance

Mats Peterson matsp888 at yahoo.com
Fri Mar 11 10:14:50 CET 2016

Mats Peterson <matsp888-at-yahoo.com at ffmpeg.org> skrev: (11 mars 2016 10:07:06 CET)
>Hendrik Leppkes <h.leppkes at gmail.com> skrev: (11 mars 2016 09:18:43
>>On Fri, Mar 11, 2016 at 5:10 AM, Mats Peterson
>><matsp888-at-yahoo.com at ffmpeg.org> wrote:
>>> Regarding the biClrUsed field, I'm setting it to 1 <<
>>> bits_per_coded_sample if palettized video, since setting it to 0 is
>>> another case where it won't work with Windows Media Player and
>>> Video 1 in 8 bpp mode.
>>This is not "spec compliance" then, because the spec specifically says
>>that when its 0, it should be assumed equal to 2^biBitCount, which is
>>the same value you are explicitly writing now.
>>Its a redundant value to work around the inability of some players,
>>not spec compliance - the existing value is perfectly compliant.
>>Please clarify as much in any potential commit message.
>>- Hendrik
>>ffmpeg-devel mailing list
>>ffmpeg-devel at ffmpeg.org
>I know all that, Hendrik, but the fact is Windows Media Player will not
>interpret 0 as 256 either for Microsoft Video 1 (CRAM) or RLE4/8. And
>the way I interpret the specs is that using 0 is only relevant to raw,
>uncompressed video.
>Mats Peterson
>ffmpeg-devel mailing list
>ffmpeg-devel at ffmpeg.org

Or I should rather say Windows Media Player doesn't interpret 0 as 1 << bits per sample in those cases.
Mats Peterson

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