[mythtv-users] ffmpeg vs vdpau decode for h264

[Tom Dexter]

On 5/15/19, Tom Dexter <digitalaudiorock at gmail.com> wrote:
> What would cause MythTV to use ffmpeg decoding as apposed to vdpau
> when playing back h264 video? A followup question to that: Is there
> any reason this would be happening more with version 30.0 than with
> 29.1? It cound be coincidence but I seem to be running into that more.
> I know there were changes related to h265, but I'm not aware of
> anything around h264.
>
> Thanks!
> Tom
>
Interesting. I was able to determine based on some of my older
frontend logs, that what I'm running into here are the same vdpau
decode errors reported here, which are causing the mythtv to revert to
software decoding:

https://code.mythtv.org/trac/ticket/13223

It sounds as though that all started after one of the ffmpeg version
bumps(?). I see that 29.1 used ffmpeg 3.2, and that issue seemed to be
related to 3.4, and version 30.0 appears to have version 4. It also
looks like there were major changes in avformatdecoder.cpp all the way
around.

I found one small example of a video where mythtv reverts to software
decoding due to those errors, yet xine on my system (Gentoo
media-libs/xine-lib-1.2.9-r2 and media-video/ffmpeg-3.4.5) plays this
using vdpau decoding just fine. It's sample #7 under the "3 Codecs,
Framerates and Subtitles" here:

https://kodi.wiki/view/Samples

That is this file:
https://drive.google.com/file/d/0BwxFVkl63-lEbVptTVZ2NENURHM/view?usp=sharing

I'd be interested to see if others find the same behavior. Most
importantly, I'd love to see if someone running 29.1 and using vdpau
can play this in mythtv with vdpau decoding.

Thanks!
Tom