cropping videos and saving them frame by frame

[onyxeyes]

Hi,

I hope somebody can help me, i am getting quite desperate. I don't have a lot of experience with video editing, however the task at hand for my master thesis seems simple enough (what makes it only more frustrating that I cannot get it to work): I have a couple of 5 to 10min long videos (50 to 100MB, mjeg, 25 frames/sec). in those videos there is only a certain region of interest to me so I'd like to crop them a bit (the area of interest is however not in the same position in all videos) to save hd memory. Afterwards I want to turn the videos frame by frame into single tiff files.

I installed transcode and cinelerra but I find them utterly confusing. I found on the web that transcode has a couple of options for cropping but they are by default disabled - how can I enable them? And I was told transcode can decompile videos - but how?

About cinelerra: I find this program extremly confusing. In the Compositor there is a crop option but ever since I used it it crops every video to the same size (which is not at all the one i want) ....

As I said I would be most thankful if someone could spare a minute and help me out on this one.

[tekkieman]

Unfortunately, I can't answer your specific questions on transcode and cinelerra, but I thought I might offer another suggestion.

You could use avidemux to crop your area of interest. The interface uses a simple point a - point b marker to select that area. From there, I thought ffmpeg might allow you to take the trimmed area, and output the frames. I started into Google, and came across rmovie (see this link ). The script would work nicely for what you are trying to do, it would just need to be encased in a loop for the number of frames needed.

Here is the syntax for ffmpeg (taken from here ):

ffmpeg -i video.flv -an -ss 00:00:03 -t 00:00:01 -r 1 -y -s 320x240 video%d.jpg

-ss record start time
-t record end time last for
So if you want to save frame 4 (00:00:04) -ss 00:00:03 -t 00:00:01. Note: it is count from 00:00:00. Even you want to save one jpg, you still need to use %d for naming,

[Steve Stepoway]

Onyxeyes, when you say "region of interest" do you mean a region in time or a 2-D region on the screen?

Cinelerra has a very steep learning curve -- definately not for the novice.

Steve