[mythtv] 2019-render: nvdec decoding artefacts in the editor

Mark Kendall mark.kendall at gmail.com
Thu Nov 7 13:08:19 UTC 2019


I've just pushed a fix for direct rendering - solves the green flashes
I was seeing and sundry issues with out of order frames.

Running through my test clips and samples this gives flawless playback
of VP9 up to 5k/30fps (probably 60fps as well but I don't have any
samples for that), HEVC 4k/60fps and H264 4k/60fps. It tries hard with
8k vp9 but runs out of memory:)

For reference, this is a GT1030 with 420.26 drivers.

I did have to adjust my audio read ahead settings to get some of these
files playing well - but that is a different issue.

The only remaining problem I see is the corruption around seeks. This
appears to only occur with interlaced H624.

The same corruption is seen when using nvdec-dec as the decoder (i.e.
copyback) and when using mythffplay - both of which are using
'vanilla' ffmpeg code with no direct rendering. A quick check with mpv
(which is using direct rendering I think, on top of ffmpeg) produces
the same issues.

So in short, this is almost certainly an FFmpeg and/or cuda issue but
I can't find any bug reports relating to it.


On Wed, 6 Nov 2019 at 23:19, John Pilkington <johnpilk222 at gmail.com> wrote:
> Now running 0822d3c with nVidia 430.40, and using High quality nvdec
> deinterlacing on a BBC DVB-T2 HD recording.  Static pictures are still
> often blocky and the 'new' shimmer after a skip is still there, but the
> most obvious new feature looks like bad frame ordering when an OSD is
> present; particularly the display of playback data.  Linear playback is
> good.
> I see rpmfusion-testing now has nVidia 440.31  I'll try that.
> John
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