Jump to content

Trying to play the video in Reverse

Recommended Posts

Hi Everyone,

      I am trying to play the video in reverse decrementing the frame number in IMAQ Read Frame function. Its working but the result is very choppy as every frame takes significant time to load, but when I just increment the frame number and play the video forward, its executing without any problem. I have attached the VI and info regarding the video, could you guys please let me know why I am having problem when I am trying to display the video in the reverse order.

Playing AVI file.vi

Video Properties.png

Link to comment

Shootballing. It may very well be that the codec used for that video is incremental, so that only certain differences from the preceding image are encoded in the next. That at least is one of the tenets of mpeg. If that is the case, I wouldn't be surprised that reconstructing what looks as an innocent predecessor requires in fact to read much more information from disk, and perhaps more computation, than a successor. If so, that seem a characteristics of the codec used rather than a limitation of LV. For reversibility, perhaps a different codec should be considered.

Link to comment

mjpeg doesnt work like that, its literally a bunch of jpegs in a wrapper. Random access should work as well as forward access. I'd bet forward access has some caching and pre-fetching though, so for random access check your cpu load, memory, and disk usage while trying to play the video. I'd bet you're hitting some limit. Specifically you are asking a lot of windows to smoothly unpack a randomly accessed frame every 34 ms using software decoding. 

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.