Extracting frames from movie gives different sized images

[dklemer]

Hello,

I am trying to use convert to extract frames from a .mwv file with a nominal size of 640x480 pixels. I have ImageMagick 6.5.8-8 2009-12-18 on Windows XP. I'm using convert with the following command:

> convert -deconstruct video_file.wmv image_file_%03d.jpg

which works great, except that some of the images are different sizes - some are 592x480, some 608x464, etc. I even tried using -resize 640x480 (which technically isn't correct, because the undersized images are more clipped than scaled), but the result is the same.

Does anyone have an idea about how to enforce the 640x480 size for every image? Any help would be greatly appreciated.

Thanks,
Dan

[fmw42]

If wmv is similar to gif animations, then the size differences are due to the fact that each new frame is just an update, not a complete frame. You might need to use -coalesce to convert each frame to a complete frame. see http://www.imagemagick.org/Usage/anim_basics/#coalesce

[snibgo]

The "problem" is the deconstruct, which will: "replace the second and later images with a smaller image of just the area that changed relative to the previous image".

If you don't want deconstruct, don't use it.

[fmw42]

Good catch Alan. I missed the -deconstruct and actually had to look that up just now as I have never used it. I don't do much with animations.

Learned something new today!

Fred

[snibgo]

I also had to look it up, but don't tell anyone.