Videoreader jitter

Hi,

I'm loading a video using VideoReader and processing frame by frame. Occasionally, it looks like VideoReader repeatedly provides the same frame regardless of index. Eventually, the reader "catches up" and gives the correct frame.

The result is that the processed video looks jittery and choppy. The jittery loading seems to occur unpredictably.

Answer 1

[Walter Roberson]

VideoRecorder is not designed for "real-time" or precision timing. Please consider using the Image Acquisition Toolbox

[Alexander Farley]

I'm not looking for real-time operation, this is pre-recorded video. The processing doesn't need to be fast. I just need to be able to reliably access each frame in the video sequentially. Is the Image Acquisition Toolbox necessary for this? Thanks,

[Walter Roberson]

What video file format is the pre-recorded video in? If it is in .avi then you can read it frame by frame using the VideoReader class.

[Walter Roberson]

Sorry, somehow earlier I read your question as having to do with VideoRecorder instead of VideoReader. VideoReader should be able to read every frame.

Which MATLAB version are you using?

[Alexander Farley]

I'm using r2011a. The videos are in .wmv and .asf format. The VideoReader class basically works except for the problem mentioned above.

Answer 2

[Image Analyst]

You're talking about extracting a single frame and displaying it in an axes, right? Not playing it as a movie and noticing some pauses or hangups? Are you sure the frame(s) in question are not in there two or three of multiple times in a row (like frames 14-18 are all the same)? Do you have some alternate way of viewing a frame at a time - like some other program?

[Alexander Farley]

I'm processing each frame in sequence. The results of the processing are written to an output video. Here you can see two different videos created from the same source:

http://youtu.be/r9Pp-vLp0QA

http://youtu.be/dHNnfm8iAGo

All processing parameters were the same. It's very strange that the results appear to vary from run to run. The processing freezes/jitters at different times in each video.

I've watched the videos in Windows Media Player and VLC; there is no jitter in the original video.

[Alexander Farley]

In addition: I initially thought this might be a hardware problem, but you can see the same problem in this video, created on a different computer:

http://youtu.be/Taxn9On4HVk

This makes me think it's a problem in my code or with VideoReader.

[Image Analyst]

Can you upload one of the original input choppy videos and tell me what frame it pauses?

[K E]

I am having problems with VideoReader appearing to read in a different number of frames each times a video file is read. I would love to know more about this problem if you figure it out.

Answer 3

[Ribas]

Did you guys know the solution for this problem?

I am analysing video and when trying to read the same frame in different tests, it gets me different frames...

[Alexander Farley]

No, I never figured out what causes this problem.