[mythtv-users] Status of ffmpeg 4.4.1

[Peter Bennett]

On 11/6/21 9:02 AM, Klaas de Waal wrote:
>
>
> On Fri, 5 Nov 2021 at 22:49, Klaas de Waal <klaas.de.waal at gmail.com 
> <mailto:klaas.de.waal at gmail.com>> wrote:
>
>
>
>
>     On Fri, 5 Nov 2021 at 21:43, Peter Bennett <pb.mythtv at gmail.com
>     <mailto:pb.mythtv at gmail.com>> wrote:
>
>
>         On 11/5/21 3:17 PM, Klaas de Waal wrote:
>>
>>
>>         On Wed, 3 Nov 2021 at 20:30, Peter Bennett
>>         <pb.mythtv at gmail.com <mailto:pb.mythtv at gmail.com>> wrote:
>>
>>             Most things are working with ffmpeg 4.4.1 in the
>>             devel/ffmpeg-resync branch
>>
>>             What is not working:
>>
>>             - Audio "upconvert stereo to 5.1 sound" when playing a
>>             video with stereo
>>             sound - error message and no audio playback .
>>
>>             - Speedup / slowdown when playing a video with dolby 5.1
>>             audio - error
>>             message and no audio playback .
>>
>>             - Report from John Pilkington that an existing bug with
>>             edit markers and
>>             step lengths now reacts slightly differently - I don't
>>             know if it is
>>             better or worse with the new ffmpeg.
>>
>>             I am looking into the 5.1 audio issues.
>>
>>             Peter
>>
>>
>>         Hi Peter,
>>
>>         As mentioned in the mythtv-dev mailing list, there are with
>>         the new FFmpeg often blocking artifacts when starting
>>         playback and when jumping forward and backward.
>>         This happens also on recordings made with the old FFmpeg so
>>         it looks to me like a playback-only issue.
>>         I do see this on my cable TV recordings which are H264, 1080i
>>         interlaced 50/25 frames per second, both HD and SD.
>>         I do NOT see this on Bluray rips which are 24p.
>>         I also do not see this on recordings with MPEG2 video coding,
>>         only on H264.
>>
>>         Hope you can have a look into this also,
>>
>>         Thanks,
>>         Klaas.
>>
>>
>>
>         I am not able to reproduce this on the devel/ffmpeg-resync
>         branch. I tried with NVDEC and with OpenGL playback profiles.
>         Which playback profile are you using?
>
>
>      Hi Peter,
>
>     Looks like it happens with VDPAU only. NVDEC, OpenGL and VAAPI
>     (that on Intel hardware) are OK.
>     So the failing combination is VDPAU/H264/interlaced.
>
> Tested some more on other recordings and there are also blocking 
> artifacts with NVDEC, but less pronounced and also sometimes the 
> stream makes a difference. If it is difficult to reproduce I can 
> create a ticket for this and attach photographs and clips.
>
> Thanks,
> Klaas.
>
>
> _______________________________________________

Hi Klaas

I do not have any H264 interlaced recordings. On Comcast we get MPEG2 
interlaced and H264 progressive. There is a known problem with MPEG2 and 
both NVDEC and VDPAU, also NVidia shield where there are frequent 
pixelations while watching MPEG2, if the stream is highly compressed as 
some USA channels are. This has been around for many years and NVidia 
seem to have no plans to fix it.

I tried with H264 progressive recordings and I do not see any problem 
with VDPAU either.

Maybe you can send a sample H260 interlaced recording. It will have to 
be long enough for me to perform skips, if that is the only way to see 
the problem. What number of seconds do you have for skip ahead and skip 
back?

Peter

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