I am experiencing choppy video playback, once I upgraded from 16.04 LTS to 17.04. Since the upgrade process passed through 16.10, I am not certain when exactly the problem was introduced.

Almost every video I play (with VLC, but also when trying to use kdenlive) begins good, but eventually starts to stall the image (while the audio is playing), then jumps to other frames etc. The stalling of videos within kdenlive is even worst (both video & audio).

How can I investigate what is causing the issue and eventually fix it?

Im also using VLC for playing videos and get an issue relevant to yours. My video stutters and freezes though, only sometimes is it choppy and that's if it's doing "OK"

Jizzoh

You should also report this to VLC, they do not use this forum.

Since you mention Kdenlive having similar issues, I move this to the correct forum.

Well, for some reason it is getting worst and worst.

Now the videos in vimeo or youtube also become choppy after some time. The bigger the videos, the worst. That is with the Opera browser.

The same happens when using Google Hangouts for a video conference. When I start the camera the system becomes very unstable.

Given the issue is occurring with several programs, I assume that this is a system problem. Any idea how to debug the issue? I.e. what should I look for in the logs, or in the process list?

The first thing to check is the RAM and Swap memory usage. Ideally you should have at least as much SWAP space as RAM for systems over 8 GM, double the amount of Swap space for systems under 8 GB RAM. Mind you, those are just rules of thumb that can be always extended. Excessive swapping can cause a system slowdown and cause the chopping in videos.

Another possible culprit could be a lack of free space. Also too many open tabs in a browser can cause a slowdown of the system. On my system both Firefox and Google tend to eat a lot of RAM when more than 10 tabs are open at the same time.

I see 2 options for the slowdown:
- display system & drivers: did you switch from X11 to Wayland in the upgrade? When I tried the latter it was much slower on my system. Could also be Intel/NVidia driver change…
- decoding libraries: almost all players are using libavcodec (from FFmpeg), it is constantly evolving and sometimes regressing…
There might be advanced developer tools to trace the problem (profilers) but I don't know how to use it in that context

kouber wrote:Well, for some reason it is getting worst and worst.

Now the videos in vimeo or youtube also become choppy after some time. The bigger the videos, the worst. That is with the Opera browser.

The same happens when using Google Hangouts for a video conference. When I start the camera the system becomes very unstable.

Given the issue is occurring with several programs, I assume that this is a system problem. Any idea how to debug the issue? I.e. what should I look for in the logs, or in the process list?

Going by the symptoms you describe, I would start by checking your CPU temperature. Overheating will cause the CPU to throttle down the speed and it will affect everything. If it's a desktop, open the case and clean the dust out of the CPU fan and heatsink.

- The CPU temperature is not related, it stays at around 50.0 °C. After some time video-conferencing in Hangouts, or looking at web pages with lots of gifs eventually the temperature rises and the fans start to blow some air. Yet, the choppyness comes quite before that.
- The SWAP partition is 8 GB, which is the same as the amount of my RAM - 8 GB.
- There is enough disk space.
- Reportedly I am using X11.
- The driver is i915.

So, I guess the suspect to point the finger at is the decoding library. I managed to make a video with kdenlive the last Friday (after loooots of patience), and I noticed that the coding/rendering part took way too long. The estimate was not accurate - it reported 5 minutes, but in reality it took 25 minutes. So there is something wrong there. Actually, something horribly wrong, it is an i7 machine with 8 GB of RAM and come on, I cannot watch movies in VLC... I should now take all my trolling on Mac OS X back...

Any ideas how I can digg further? Thanks for your assistance so far, guys.

Is it worth trying another desktop environment, such as Unity or XFCE for instance? Would it make any difference?

If you cannot even play videos properly in vlc, it is not a plain kdenlive issue. Did you change video drivers during the update? If so, did you uninstall the old driver properly? Are there config files left?

Render time estimation is nothing to rely on. kdenlive does not look ahead how many effects are transitions have been used and how many video tracks have to be merged. So the render time varies widely and changes during the render process.

capslock wrote:If you cannot even play videos properly in vlc, it is not a plain kdenlive issue.

Indeed, that's what I am stating as well, it is not a kdenlive issue, but a system issue.

capslock wrote:Did you change video drivers during the update? If so, did you uninstall the old driver properly? Are there config files left?

No idea. I just followed the upgrade process (from 16.04 LTS, through 16.10 and to 17.04) and ended up in this situation. There weren't any issues with 16.04 LTS, everything was working perfectly well.

I update my debian sid about every month, and last time (mid july) video playback became very slow.
Downgrading to debian stretch did bring situation back to normal.
Kdenlive were both 16.12.2-1, MLT both 6.4.1-4, but FFmpeg (libavcodec) changed from 3.2.5 to 3.2.6.
I believe we should look into that direction: look for bug reports or file a new one.
Note: building MLT shows several FFmpeg warnings about deprecated API...
maybe MLT calls old functions that got broken somehow?