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Strange encoding glitch with H.264 and DivX

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Sunny Singh
Strange encoding glitch with H.264 and DivX
on Jun 13, 2009 at 2:31:19 pm

Greetings, all. I've noticed a very peculiar glitch when I attempt to compress some of my raw .avi files. I first noticed it when I compressed the video to DivX, and again when I attempted it with H.264. It may also occur with other formats I have not yet tested.

The problem is as follows: at approximately 9:26 into the video (any video of mine, actually), the frame flickers green (see screenshots below) and it is accompanied by a high pitched beep. I thought something minor had happened during the encoding process, but here's where it gets strange. This error not only occurs at 9:26, but also roughly at every integer multiple of 9:26. For example, the same problem manifests itself at 18:53 and so forth.

The videos I'm encoding are about 40 minutes in length, so you can imagine how annoying these glitches are. What's more, this frame flicker/beep does NOT appear in the raw .avi file.

1 frame before glitch:
http://hate5six.com/glitch/frame1.png

Glitch:
http://hate5six.com/glitch/frame2.png


Machine Specs:

2.4 GHz P4 running Windows XP (32 bit)
1.5GB RAM
1TB of space between 3 drives (each 7200rpms)

The .avi's are generated using Premiere Pro 1.0 and/or Premiere Pro 2.0. Encoding has been tested with the following: Dr. DivX, h264, and Handbrake.

It's obviously an older machine, but I perform maintenance routinely and everything *seems* to be okay with it. It performs well enough for the editing I do, it's just the encoding process that goes awry.

Does anyone have any clues as to why this might be happening? I would venture to say this problem is something "under the hood"--in the way the computer resources are being handled during encoding (RAM allocation, cyclic/periodic drive operations, etc). I would just like to identify the point of failure.

Thanks in advance!


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Sunny Singh
Re: Strange encoding glitch with H.264 and DivX
on Jun 13, 2009 at 10:27:35 pm

Okay, things just got even weirder!

The problem has been replicated on an older, albeit different, machine (1.06GHz Athlon, 384MB RAM). The glitch is again appearing with the same exact regularity at every 9 minutes and 26 seconds in the video(s).

I then transferred the raw avi file from my Windows machine to my Linux box in an attempt to test a compression on that box. The entire file transferred over successfully (roughly 36 minutes long). VLC plays the video fine and indicates the correct duration of 36 minutes. However, another player (Totem to be exact) registers the video as only being 9:26 in length!


Now I'm starting to think it's a problem with the exported avi...


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Daniel Low
Re: Strange encoding glitch with H.264 and DivX
on Jun 17, 2009 at 10:12:54 am

[Sunny Singh] "Does anyone have any clues as to why this might be happening?"

It could anything but if it happens after a set length of time with any video, then it's possible that it's RAM related.

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