I'm assuming you mean, where the data in the AVI is? You can read up on the specs if you want to read directly from file: (RIFF) and (AVI). The actual image data is in sub-chunks under the "movi" list.I'm wondering if anyone knows off-hand where the data for the frames will reside?
Also, from what I read, a lot of people working with video use OpenCV to help with processing, it might be worth looking into. (Though I admit this is definitely not my area of expertise )