[CrystalP]

Still perfect here (Windows) when clicking on next/prev chapter buttons of OSD.

[Bindou]

@Bindou : I'm also seeing problems when using the player GUI elements to skip forward to the next chapter. Backwards works. Using the up/down buttons on the keyboard or remote also jumps forwards/backwards by chapter without issues. Selecting arbitrary chapters from the chapter list also has no issues. Can you confirm the issue only exists when using the player GUI controls?

My system is Arch running current master.

Unfortunately, I'm experiencing two different issues. When I click on the shortcut forward or back a chapter (from the OSD or from a remote control shortcut) it is sometimes impossible for me to go back a chapter. As seen in the video. Also, when I view the thumbnails and click on them, sometimes it literally crashes the movie.

[Bindou]

You mention skipping to next/previous chapter, but does the same thing happen with jumps? They're the same internally in Kodi.
If so can you share a short sample that shows the problem on your box?

See my first post.

[Bindou]

Impatient much? anyway, it's not a general support issue, but linux and possibly corelec specific. I don't do linux, maybe someone else will know if it's a known issue. The corelec forums could be a good place too.

12/04
Can you say that I am patient? All joking aside, I have a feeling I'll never find a solution for this bug.

[CrystalP]

Lol well I tried to be patient too but the download from Mega got stuck every time I tried, then I hit the limit for the free tier...
Samples are usually much smaller, like 30 seconds - a hundred megs or so. It seems you included a whole chapter given the size. If you must include an entire chapter, then make it from a SDR low bitrate so the sample size remains small.
Or edit the chapter points with the help of mkvtoolnix to create a chapter of 10 seconds for example... We just need to see something easliy shared that shows the issue on your system.

[Bindou]

Unfortunately I no longer have the tools to do better at the moment. But I'm surprised you can't download it easily, I just tried and it took 2min. I put another extract with 4 chapters. https://mega.nz/file/AfEkHSrY#anooqQoprF...ju5DUa3xLs

Thanks for trying to help me anyway.

Do you have Kodi on CoreELEC?

I summarize all the information on the first page, if you want to understand better...

[Bindou]

I don't know if this can help definitively decide whether it comes from CoreElec rather than Kodi, but I would like to share this conversation: https://discourse.coreelec.org/t/chapter-bookmark-issue- still-present-after-a-reset/51244/12

[CrystalP]

I was able to download the sample finally, and with or without hardware acceleration, no glitch. with remote, with OSD buttons, through bookmark/chapters, ... (Windows on desktop PC)
I'll say that the chapter points are not optimal and do not fit the video well. Broken by a reencode of the original maybe? After selecting some of them you can see the current position quickly going backwards/forward. Not fatal as my testing showed.

Hardware decoding is still the likely culprit, but it cannot be clearly confirmed with that video on your device because it's not powerful enough to decode it without hardware assistance.
Find another lighter video that still shows the issue with hardware decoding and is smooth with software decoding.
You may have to go down to H264 codec and 1080p or lower, or even further down to mpeg/xvid and dvd resolution. It depends on the strength of your CPU.
Then test the chapter jumping with hardware decoding off.

[Bindou]

Thank you @CrystalP for this new avenue of research. Ok, I will experiment with this as soon as I can.

Unfortunately for the moment the CoreElec developers don't really seem to be able to focus on this problem. I will therefore continue to provide them with as much information as possible to help them. If you are ever interested in helping here : https://discourse.coreelec.org/t/chapter...t/51244/22

i.e. a hypothesis has been raised : " As for your question regarding Android, that is actually relevant. It seems that Kodi on Android is not seeking to nearest keyframe after a chapter marker, but instead the nearest keyframe before the chapter marker. The stall you observe is Kodi decoding the few seconds of video from the previous keyframe to the actual seek time to get back in sync. "

[CrystalP]

It doesn't help. You need to show the problem on a Kodi supported platform, otherwise the issue doesn't belong here.
You could try a standard linux distribution on the box and see what happens.

The major difference between Kodi v20 and v21 was the ffmpeg version. Behavior may change a bit again with v22 because of an upcoming bump to ffmpeg 7.

[Bindou]

To finish here, I wanted to share with you the progress on this problem.

Portisch (CoreELEC Team) :

Please try chapter seek with tomorrow nightly, CE-21 20240425, again.

There was a patch from early CoreELEC days still applied to Kodi.
This patch was need in past because the seek did might not end up on a keyframe.
So it did a step forward to the next keyframe. This cause like in this example a diff of 10 seconds between chapter position and keyframe position. And this did lead to a lock out in the chapter seek function.

I guess Kodi seek does now end up on keyframe since a while ago so this extra seek is not need anymore.

Bindou :

Thank you very much for your interest Portisch. For my part, after testing several problematic films, the chapter passage bug is resolved. This is really good news. However, I still have the problem of thumbnails not displaying. And when you click on it, the movie currently playing stops immediately.

What we can see at the 25th second : https://youtube.com/watch?v=LLptQ5pNKrY 1

[Bindou]

Hi @CrystalP, the diagnosis is progressing. The first part of the problem is fixed and indeed came from CoreElec. On the other hand, the second part of the problem seems rather linked to Kodi. I talk about the problem with displaying chapter thumbnails that you can see in the second part of my video (in my first post -> 25s). According to the CoreElec team, the problem is reproducible on Kodi Windows. Assumption: UTF8 chapters with names with special characters (accents, etc.) are not supported. What do you say ?

[Bindou]

Strangely enough, it doesn't work on Kodi CoreELEC, nor on Kodi Windows (according to the CoreElec team), but it works perfectly on Kodi Android. Would Kodi Android benefit from better compatibility than Windows with reading chapters ?

[CrystalP]

We need a sample to reproduce the issue and a debug log.
At the very least extract the chapters of your file so they can be injected into another file.
The Terminator sample you provided doesn't show any problem here.

[Bindou]

Sorry CrystalP, apparently other testers were able to confirm that the problem was only present on CoreElec. So you can close this issue if you want. Sorry for the waste of time.

-> https://discourse.coreelec.org/t/chapter...e/51244/44