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

[Robert Krüger]

On Wed, May 14, 2014 at 10:38 PM, Andy Furniss <adf.lists at gmail.com> wrote:
> Robert Krüger wrote:
>>
>> On Tue, May 13, 2014 at 5:30 PM, Andy Furniss <adf.lists at gmail.com>
>> wrote:
>>>
>>> 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.
>>>
>>
>> If my understanding is correct the subsampling part is not the
>> encoder's job, so it should not matter here. The encoder encodes an
>> already subsampled raw signal, so if something is wrong regarding
>> subsampling, it happened before the encoding step.
>
>
> True, what I was really wondering, was whether in the attempt to get
> full range using yuvj you were going to get something other than expected.
>
> I tested converting yuv444p to both yuv420p and yuvj420p and the results
> are identical - so it seems that libswscale doesn't differentiate

I think if that is the case, you should file a bug report with the
exact command line you used. If you mean the results were numerically
identical, that should not be the case and I have not observed this
when I transcoded to yuv420p and yuvj420p.