Issue with skip forwards or backwards

General
1

By chance, I came across a small issue with skipping forwards or backwards on SDR videos only (I have no HDR files) , using hardware decoding. AFAIK, this still happens with latest Omega-ng.

I managed to trace the issue to the nightly that was released on 20 March 2024 for Omega-ng (CoreELEC-Amlogic-ng.arm-21.0-Omega_nightly_20240320). The previous nightly compiled on 19 March 2024 (CoreELEC-Amlogic-ng.arm-21.0-Omega_nightly_20240319) works perfectly. After skipping (10 sec, 30 sec, 1 minute, 3 minutes, 5 minutes, 10 minutes, 30 minutes etc) either forward or back, there is a jerkiness in playback (most of the time) immediately after the skip has completed. Sometimes, the jerkiness is very slight, sometimes it is very pronounced and obvious. This only lasts a second or so and normal playback is then resumed.

I have S905x2 and S905x4 boxes and it happens on both. With the nightly “CoreELEC-Amlogic-ng.arm-21.0-Omega_nightly_20240319”, skipping forward or back shows no jerkiness at all and the transitions are perfect. I went back to previous versions of CE - Nexus 20.5, Leia 18.9 I had available, and all had perfect transitions.

I investigated further and found that the cause could possibly be changes made to the kodi file xbmc\cores\VideoPlayer\DVDCodecs\Video\AMLCodec.cpp. Looks like this file undergoes a lot of changes over time.

I compared this Kodi/xbmc file from 17 March 2024 (most recent kodi changes before 19 March 2024) with the kodi file from 19 March 2024 (problem was introduced here) and the diff file is attached. There were about 6 lines of code changed between these two versions and relates to a “buffer level”.
AMLCodec.patch (1.5 KB)

The issue happens on all my local videos (video resolution is not important). It’s a very minor issue and if you never skip forward or back, the problem is never seen.

I thought you should be able to test for yourself with any video. If you use latest Omega nightly or latest release (21.2 Omega-ng etc), the issue should be present.
I did a brief test with latest Piers-no nightly and the skipping is a lot improved over Omega-ng 21.2. I’m quite happy with the “21.0-Omega_Nightly_20240319 release” if there is not enough time or desire to fix this. I do appreciate all the unpaid hard work you all put in to the project.

I am aware of a similar issue related to “NAL Skip Policy” being set to “2” or “1” that was reported on Feb 1, but this appears unrelated:-
Time skipping produces HEVC video artefacts since CoreELEC 21.0-Omega - Help & Support / Ugoos - CoreELEC Forums

2

I managed to fork CoreELEC etc and recompile the version without the skipping issues and test it, just to make sure. That worked fine. I then added the changes from the patch I uploaded in my previous post, to my fork, and recompiled. The issues did indeed appear. On some videos, playback was really bad. I appreciate these changes may only be a part of a larger overall change and a lot of changes have been made since to that one file (AMLCodec.cpp), but it does appear to prove where the issues started for 21-Omega-ng. As said, I still see the jerkiness after skipping on 21.2-Omega-ng, however 22-Piers-no is a lot better.