[mythtv] Redone FFmpeg 4.4.1

[Klaas de Waal]

On Sun, 28 Nov 2021 at 02:33, Peter Bennett <pb.mythtv at gmail.com> wrote:

>
> On 11/27/21 12:55 PM, Klaas de Waal wrote:
> > A quick test of devel/ffmpeg-resync just now shows that on playback
> > any skip terminates playback. There must be something wrong with
> > either the new merging or with the new commits.
> > The current master skips OK at least on vaapi (intel hardware).
> >
> > Possibly anticipating your new sync instructions...
> > If I understand correctly the workflow to do FFmpeg bisecting, along
> > the lines of "checkout ffmpeg, copy everything across, apply the
> > patches, rebuild MythTV and test" should now be possible. Some
> > scripting to support this would also be appreciated...
> >
> > Klaas.
> >
> I have no problem with skips, using vdpau. Is that something specific
> with vaapi? I tested with your twee voor twalf recording as well as
> others. For the twee voor twaalf I had to set skip to a few seconds for
> testing as the clip is only 1 minute long.
>
> Peter
>
> Skipping is OK for recordings. Skipping fails for video files. The video
files here do not have a keyframe index and hence on a skip the file is
read until the correct frame is found. The code for this is now broken
devel/ffmpeg-resync. There are changes in
libmythtv/decoders/libavformatdecoder.cpp around line 1250 which could be
related to this.
On a skip forward I get the following messages:
2021-11-28 09:49:35.952899 E  AFD: av_seek_frame(ic, -1, 71589090311, 0) --
error
2021-11-28 09:49:35.953703 E  decoding error End of file (-541478725)
2021-11-28 09:49:36.429194 E  decoding error End of file (-541478725)
2021-11-28 09:49:36.509610 I  TV::HandleStateChange(): Attempting to change
from WatchingVideo to None
What happens here is that the skip forward reads to the end of the file and
then fails.
The av_seek_frame error is the one that should not be here.
This is independent of video decoding; I tried this with vaapi and vdpau.
This is also independent of the video coding; it happens here both with
H264 and MPEG2 encoded recordings.
Note that the current master skips OK.

Klaas.
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