I had noticed a short "burp" at the same point when playing back a project that I had made two years ago. It wasn't serious and I ignored it.
Yesterday, I created a new deinterlaced and up-rezed video file, from that project. When I played it back, it stalled and went blocky at the point of the "burp".
So, I examined the source video file, with Virtual Dub, near the burp point, frame by frame and discovered a single frame that had two interlaced fields - but each field belonged to a different scene.
This footage had been captured direct to Mpeg2 from my analog camcorder using ADS Instant DVD II and CapWiz. Evidently, this combination does not try to detect scene changes before constructing an interlaced frame and so, created a frame with completely different content in each field. This seems to have driven the Divx deinterlacer a bit crazy... I removed this frame, created a new video file - the burp was gone and the deinterlaced version was perfect.
In retrospect, this could be a lot more common than it seems because any single scene change from an analog camcorder has a 50-50 chance of falling within a single interlaced frame. Ditto digital camcorders, unless they (internally) detect the fact that recording was interrupted, and conditionally construct a "double-field" frame at that point.
Bottom line: If you have an unexplained problem with your video project, examine the source clips frame-by-frame with Virtual Dub. Download from http://fcchandler.home.comcast.net/stable/
Video Scene Change Within Frame
Moderator: Ken Berry
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jchunter
Steve,
Video Studio is not capable of displaying both fields of an interlaced frame in the preview screen. VirtualDub can. It can also tell you the function of each frame of any GOP (I-frame, B, P, etc.). OTOH, VD doesn't make a very good playback program.
BTW, I searched for other instances of scene changes within a frame and found several. Clearly, not every one was causing problems. Something else had to be corrupt in my specific problem frame.
I did use VD to checkout another problem area in an old capture clip, where about 10 frames were messed up (very blocky). I tried to repair the clip by re-rendering with Smart render disabled but it did not work. I ended up deleting the whole GOP. and all was well again.
Video Studio is not capable of displaying both fields of an interlaced frame in the preview screen. VirtualDub can. It can also tell you the function of each frame of any GOP (I-frame, B, P, etc.). OTOH, VD doesn't make a very good playback program.
BTW, I searched for other instances of scene changes within a frame and found several. Clearly, not every one was causing problems. Something else had to be corrupt in my specific problem frame.
I did use VD to checkout another problem area in an old capture clip, where about 10 frames were messed up (very blocky). I tried to repair the clip by re-rendering with Smart render disabled but it did not work. I ended up deleting the whole GOP. and all was well again.