[FFmpeg-user] Creating ffv1 full-range and broadcast-range files

[Andy Furniss]

Robert Krüger wrote:

>> I also am not qualified in any way, but one thing to consider is
>> sub-sampling positions.
>>
>> I don't know what ffmpeg does, so it may make no difference, but
>> AIUI jpeg/mpeg1 420 is slightly different from >= mpeg2. Maybe it
>> makes no difference, but I suppose there's a chance that it could
>> if conversions are involved.
>
> I compared the decoded frames' md5 hashes from the original mjpeg
> stream and the ffv1 video (see earlier in this thread), so I would
> assume that this does not seem to be a problem in this case.

Yea - but the test was already yuvj, so no conversion from something
else involving subsampling.

TBH I have no idea whether this is an issue or not - I could well
beleive that my AMD gpu yuv -> rgb does whatever is convinient with
sample positions and the difference is barely visible (ISTR the OSS
intel guys did fix up either their driver or mesa to do it properly)

I am guessing your issue is ffmpeg (auto?) conversion rather than ffv1
as such. I can get ffv1 to use full range yuv OK, but the source
was mpeg2 giving "normal" yuv and I assume your problem with ffv1 when
faced with incoming yuvj is that ffmpeg inserts a filter that by default
crushes the levels.

I haven't got time to look now, but ISTR seeing an option somewhere that
could help with full range, the thing is it was a long time ago and I
don't think it worked - but then as I don't do things for real I
probably didn't try too hard.