[mythtv] Call for testing devel/ffmpeg-resync (FFmpeg 5.1)

[Peter Bennett]

On 9/7/22 19:06, Scott Theisen wrote:
> On 9/6/22 17:46, Peter Bennett wrote:
>>
>> On 9/6/22 14:46, Scott Theisen wrote:
>>> Hello all,
>>>
>>> I have merged FFmpeg 5.1 into our version and copied it into 
>>> MythTV.  Peter Bennett has pushed these commits from 
>>> https://github.com/MythTV/mythtv/pull/627 to devel/ffmpeg-resync and 
>>> we would appreciate further testing before it is merged to master.
>>>
>>> The deprecated avcodec_encode_video2 has been removed.  I modeled 
>>> the replacement code on the audio version and would appreciate some 
>>> testing of transcoding to make sure my replacement works. There is 
>>> also a similar change to NuppleVideoRecoder, but I don't know if 
>>> anyone actually still uses that.
>>>
>>> FFmpeg has created a new channel layout API and deprecated the old 
>>> one.  This effects downmixing and I would appreciate confirmation 
>>> that it still works as expected on non-SSE2 platforms.
>>>
>>> Those were the main things I wanted tested, but general testing 
>>> would also be appreciated.
>>>
>>>
>>> Klaas,
>>>
>>> Could you test the attached patch on top of devel/ffmpeg-resync to 
>>> test if https://trac.ffmpeg.org/ticket/9532 is still a bug? Apply 
>>> the patch in the mythtv/external/FFmpeg folder and test VDPAU 
>>> decoding with your sample.
>>>
>>> Thanks,
>>>
>>> Scott Theisen
>>>
>>>
>> I still have that video on my test system. IIRC it used to pixellate 
>> in various places in the video before Klaas's patch. Using VDPAU. 
>> with the ffmpeg-resync version it plays perfectly. With the 
>> ffmpeg-resync version and the revert patch it pixellates badly for 
>> 2-3 seconds at the start of the video but not at any other place. So 
>> the problem may have partially been fixed in ffmpeg.
>>
>> Do you have a version of the revert patch for master so that I can 
>> apply it there as a comparison for how it used to be?
>>
>> Peter
>
> See attached for patch to master.  If I recall the discussion 
> correctly, there should be blocking/pixellation on skipping in 
> addition to the start.
>
> Scott
>
> _______________________________________________

I have to set my skip amount vary small (10 seconds) to test skipping 
because the entire clip is only 1 minute.

Both master with the revert patch and ffmpeg-resync with the revert 
patch show pixelation at the start and sometimes after skipping. There 
is no difference. Both master and ffmpeg-resync are perfect without this 
patch. It seems the underlying bug is partially fixed in both master and 
ffmpeg-resync with your revert patch. The pixelation on skipping is only 
one time out of ten. Have you backed out Klaas's fiox completely with 
the revert, or possibly only backed out part of it?

VLC player (3.0.17.4-2~22.04.sav2)  shows the pixellation on that clip 
every time after skipping, so it is worse than mythfrontend is now. I 
think this is how mythfrontend was initially behaving before Klaas's fix.

Peter