Playing very low frame rate video

[hbaker1@pipeline.com]

Although the following question has been asked many times before on the VLC forum, it has never been properly answered:

How to play low frame rate videos?

The problem is that when VLC fails to play these videos, VLC gives no indication that anything has failed; VLC simply refuses to display or (in some cases) update the video.

I don't know the internals of VLC and haven't looked at the code, but the following recommendation is a result of some experiments on the latest Windows VLC (2.0.5).

After running a number of experiments on videos of different frame rates, it appears that the problem is the amount of "File caching" required for low frame rate videos.

My experiments indicated that if F = # frames/second and C = amount of file caching in _seconds_, then you need F*C >= 3.0 seconds or thereabouts.

Thus, if F=0.1fps and C=30000 msec, then F*C >= 3.0 seconds and the video will play correctly.

Note that VLC won't allow a "File caching" parameter >60000msec = 60 seconds, so VLC will probably not be able to play a frame rate of < 0.05 fps = 1 frame every 20 seconds.

The good news is that some popular very low frame rate videos -- e.g., the .1fps videos from the KITP institute at UC Santa Barbara _can_ be played correctly with VLC after the file caching parameter preference has been set to 60000:

http://online.kitp.ucsb.edu/online/bblunch/rss.xml

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I would recommend to the VLC developers that this file caching parameter be redefined in terms of video _frames_, rather than milliseconds, as 60 seconds of high frame rate high definition video could be an enormous buffer. By specifying the file caching in terms of frames instead of seconds, the size of these caches can remain reasonable for most types of video.

[Lotesdelere]

VLC has troubles to play low frame rate videos, it's a known issue awaiting for a fix.
You can try to increase the cache.

[dbareis]

And we still seem to be waiting for the fix?

[Rémi Denis-Courmont]

Yes. Patch welcome.

[unidan]

Hi, this might be fixed in 3.0.8 and 4.0.

[awakecoding]

Hi,

I have registered just for this bug, which has been a pain point for us for several years already. We do remote desktop session recording, where the frame rate is variable, but also oftentimes *very* low. As a workaround, we've been re-encoding identical input frames to force a minimum frame rate of 5 fps, which is wasteful for the encoder. We've got our own WebM encoder using libwebm + libvpx, and while Chrome can play the video files correctly, VLC is basically useless below 5 fps.

When can we expect a fix, and how can I help? We've been re-investing some time in our remote desktop recording solution and if VLC can't play the video files correctly, we'll be stuck being unable to encode just the frames we need. Since this is for real-time encoding and streaming, you can imagine why we'd rather not waste time re-encoding unchanged frames (waste of CPU cycles, but also increased file size, etc).

[Rémi Denis-Courmont]

You can expect a fix when somebody makes one, and you can help by contributing a fix or hiring somebody to do so.

[Sir Trancealot]

Hi, I have just deactivated deinterlace mode and the videos have started playing at the normal frame rate.
OK, most of my videos are made of torrents (ahem), but the frame rate issue only occurred on various videos. Some played fine others were barely watchable.
Just a video setting may help. If that doesn't help, it may be a buffer issue. Try restarting your videos. If the problem still occurs then I am at a loss. But this setting changed helped me.

EDIT One final solution is to go to tools, input/codecs, and disable Preload MKV files in the same directory. Restart VLC. I realised this problem only occurred when opening MKV files.