Why doesn't VideoReader(filename) return?

I'm runnin the following code:
v = VideoReader('video.mp4')
on a video that plays with no problem in my media player, but the function just "hangs", i.e. doesn't return at all. I can't even pause execution or kill it with Ctrl+C, I have to force the whole Matlab session to end while potentially losing unsaved work.
Trying to debug this and 'stepping in' whenever poosible, I get to line 271 (function 'open' in the script
'C:\Program Files\MATLAB\R2020b\toolbox\shared\asynciolib\+asyncio\Channel.m')
% Gain exclusive access of the device.
obj.ChannelImpl.open(options);
which doesn't return. Matlab version is 2020b. Any help would be highly appreciated.

4 commentaires

Aditya Patil
Aditya Patil le 5 Avr 2021
Does this issue happen with only this file, or other videos as well? Would it be possible for you to share this video file?
Boldizsár Balog
Boldizsár Balog le 27 Mai 2021
I was facing the exact same issue, using the call you can see in the question. I've only met blocking behavior with a low resolution (32 px x 18 px), 60 fps video about an led, which I attached. I rendered this video with twice as many pixels (64 px x 36 px), with the same frame rate (60 fps) as well, and red the video successfully. The videos exceed the 5 MB limit, you can download them from this link: https://transferxl.com/08vFVGwmFXg5Hz . If it is not working I'll upload it somewhere else.
asaf benjamin
asaf benjamin le 4 Août 2021
This issue happens with several videos (but not all videos, of course). An example video can be found here. Thanks!
I can now confirm that, not only does the video play with no problem in any standard media player, but it is also read with no problem in Open CV, simply using:
vidcap = cv2.VideoCapture(vid_name)
success, image = vidcap.read()
I'd prefer to use Matlab for this, but if there's no solution to the problem I guess I'd have to move to Python instead...

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