Flip video avi frame indexing issue

[Synthetik]

We've recently discovered an issue with source video from Flip video cameras i wanted to document here since it has implications for anyone using Quicktime video files from these cameras with Studio Artist. The Flip camera outputs avi video files on the mac that use the 3ivx mpeg-4 codec. It turns out there's a weird problem associated with using these files for single frame access using the Quicktime apis we use in Studio Artist. Basically, when we tell Quicktime to go to a certain frame time in the video and then place that frame image in an offscreen buffer for processing, the actual frame that Quicktime places in the buffer is not always the correct frame for the frame time we passed to Quicktime. The problem appears to be tied to the synch frame indexing in some way, since you see this weird behavior happening every 20 frames. So when we ask for frame 2 what we get passed back is frame 5, when we ask for frame 22 what we get passed back is frame 25, etc. So if you single step through the frames in the video you will see the action skip ahead, then behind at the next frame, then move foreword normally until the next frame skip 20 frames later. This problem only happens with avi files taken directly from the Flip camera. It does not happen with any other kind of Quicktime video file that we are aware of. So for now, the easy fix to this problem is to export a copy of your Flip video from Quicktime Player Pro using a different compression codex other than the original 3ivx mpeg-4 codec. If you do this and then use the exported video file as your source video in Studio Artist you won't see this problem occurring every 20 frames. You will see an initial frame offset associated with frame 0, since Quicktime Player 7 displays a time offset frame for the first frame of these avi video files as opposed to displaying the correct frame. So you might want to trim the first frame of these videos prior to exporting from Quicktime Player Pro to fix this. We're in discussions with FlipVideo and Apple to try and get this issue resolved. You see the exact same single step frame jump behavior in the FlipShare video management application on the mac that comes with the Flip camera. Kind of frustrating for me, since i love the Flip camera and have been using it quite a bit with Studio Artist. Again, the solution for now is to use something like Quicktime Player Pro to convert your original Flip video footage into a different compression codec and then use that exported footage for processing.

[Donna Kuhn]

i usually save the flip files as .mov. i haven't seen a problem.

[Synthetik]

If you save them as a mov file you won't have a problem. It's a bug with the particular avi codec and quicktime they use for their native avi files the camera records.