Micah Richert

Hi Kevin,,

Sorry for the delayed reply. I'm not sure why struct returned by mmread doesn't work for you, specifically v.nrFramesTotal. if nrFramesTotal is positive it is the number of frames in the video, if it is negative then the video doesn't report the total number of frames and nrFramesTotal is estimated from the frame rate and duration of the video. So, the following code should work for you:

v = mmread('somevideo.mpg',1);
if v.nrFramesTotal > 0
  vlast = mmread('somevideo.mpg',v.nrFramesTotal);
else
  % estimated last frame, try reading past the end of the video, after which nrFramesTotal will be accurate.
  vlast = mmread('somevideo.mpg',-v.nrFramesTotal*1.01);
  vlast = mmread('somevideo.mpg',v.nrFramesTotal);
end

Hope this helps,
Micah

Hi Chris,

640x480 uncompressed video requires 640*480*3 bytes per frame or just under 1Mb of memory. If you capture for 2 minutes at 20fps that is 640*480*3*20*120 or 2.2Gb of memory. So, it is of no wonder that you are getting out of memory errors; also 2Gb is the most memory 32-bit Matlab can allocate.

To get around these issues, either read the video in smaller chucks or use the processFrame interface. Or use mmreader since you are using a newer version of Matlab.

Best,
Micah

Hi Huang,

Can you include the actual error message when it crashes? Also, are you using 32 or 64 bit Matlab?

Best,
Micah

No its ok
I1=video.frames(100).cdata;

I'm having trouble getting mmwrite to work. I get errors looking for a module in mmwrite.mexw64: "??? Invalid MEX-file 'U:\MATLAB\MovieTest\mmwrite\mmwrite.mexw64': The
specified module could not be found." I added the path via addpath. Any ideas?

Thanks,
Howard