Movie In lag/jitter

Beginners
1

I’m seeing frame jitter a few times a second. It seems to be no missing frames, just occasional mistimings in playback. The quicktimes are looping, and don’t page from the hard drive. The performance CHOP shows a minimum of 50fps (on a 29.97fps file), peaking above 200fps. The performance monitor shows Draw Touch UI as the biggest hit, at an average of 10msec, ranging from 4 to 22msec, but even at max the Total Frame Time is 33.956. The glitch is more frequent than the >33msec Total Frame Time responses.

CPU use is under 20%. HDD is not involved. LIBAVcodec. Win7-64bit. nVidia driver v.197.45. I’ve played with all the Tune choices on the MovieIn TOP and don’t see any difference.

What might be causing this?

-russ

2

I’ve been having very similar problems on a few different projects lately… similar specs and results. An odd workaround, but I’ve found that deleting and re-creating the TOP solves it… :confused:

I’ve setup these projects so that my start script opcreates and opwires them…

3

Is it just one file or all the deifferent videos you load in?

4

Different files, but same TOP for me… just about to test with the latest experimental…

5

For me it happens with all files in all encodings. No apparent difference in frequency of the jitter. Playback of the files in QTviewer is smooth.

I’ve heard from friends that it happens with commercial video server boxes that run on Windows, too, so maybe it’s inherent in the OS somehow.

There are different amounts of jitter sometimes, but it’s unrelated to whether I’m pushing multigigabyte files, choice of codec, etc.

I’ll try the delete and replace trick. Thanks for the idea.

6

We’re actually experiencing and looking into solutions to this ourselves for our own projects.
Some of the things we’ve learnt so far:

  1. Be careful if you are using CHOPs to drive the index, roundoff errors can cause indices like 19.99999, which would cause frame 19 to get played instead of 20. Use the Limit or Math CHOP to round the values.

  2. A 29.97 movie will always have a jitter every once in a while, since it’s impossible for a 60hz monitor to stay in sync with a 29.97 FPS movie. Every once in a while a movie frame will get displayed for 3 monitor refreshes. Try to use 30 FPS movies (or just override the sample rate to 30 in the Movie In TOP)

  3. If you are below 60 FPS, you can’t guarantee that each movie frame will get displayed for 2 monitor refreshes. The GPU doens’t know you are trying to play a 30FPS movie, so it doesn’t know to keep each frame for 2 refreshes. It’ll try to get them to the monitor ASAP, so you may get some frames that are displayed for 1 refresh, and others that are displayed for 3 refreshes. We are trying to find a good solution to this problem right now. Our testing shows that this problem shows up in QT and VLC Player also.

7

I think I just sorted out my issue - though Im not sure if it will help anybody else…

my issue again was that my video playback was getting stuck on certain frames, though my index seemed to be playing fine… then i realized that this portion of the playback is happening - similar to many other projects we are working on - from an external tox that was still from an older build (maybe even 3715?), so i just updated that tox with one re-exported from a more recent build (5642) and all is rosy! :blush: … but, all things being equal, this was just a moviein top…

8

Old Build was 5294 if that helps…