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

[Andy Furniss]

Robert Krüger wrote:
> On Fri, May 9, 2014 at 4:30 PM, Robert Krüger <krueger at lesspain.de>
> wrote:
>> On Fri, May 9, 2014 at 3:24 PM, Carl Eugen Hoyos <cehoyos at ag.or.at>
>> wrote:
>>> Robert Krüger <krueger <at> lesspain.de> writes:
>>>
>>>>> Did you test what happens if you replace all occurrences of
>>>>> AV_PIX_FMT_YUV420P in libavcodec/ffv1enc.c and
>>>>> libavcodec/ffv1dec.c with AV_PIX_FMT_YUVJ420P ?
>>>>
>>>> I just tried and the resulting file checked with the histogram
>>>> filter appears to have the correct (full-range) levels.
>>>
>>> The more important question is if the output is bit-exact?
>>
>> I checked a more complex yuvj420p sample and the framemd5 output
>> is identical, so I would say yes.
>
> would you say, submitting a patch that just adds this pixel format
> instead of replacing AV_PIX_FMT_YUV420P makes sense? The risk here
> is only that I would probably not be qualified to deal with problems
> that require a deeper understanding of what is going on there but so
> far it looks like it could "just work".

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.