R – FLVs on timeline are glitching out

actionscript-3flashflvmemoryvideo

I have a Movieclip with about five FLV movies embedded on its timeline, one after another.

I am loading multiple instances (about 5-10) of this movieclip onto the stage. Once added to the stage, they each play there timelines in a loop.

The problem is that when one of the instances switch over to playing a new FLV, then some of the other instances "glitch out"! See this image for what the glitch looks like:

alt text
(source: adamharte.com)

This glitch also happens when they first start playing (first load).

More details of Flash:

  • 24fps
  • FlashPlayer 10
  • Actionscript 3

More details of the FLVs:

  • Encoded with On2 VP6
  • 24fps
  • transparent background (alpha channel)
  • dimensions 640×480
  • filesize are about 150KB each
  • FLVs are imported using option: "Embed video in SWF and play in timeline"

Has anyone seen this before? Does anyone have a reason for why this might be happening? And any possibly ways to stop it from happening.

EDIT*
It seems to only "glitch" when an FLV is started from a random frame (a frame that is not the first frame). I don't think it always does it, but it does it quite often.

Best Answer

I would say one of two things is probably happening:

  1. The video elementary stream is being corrupted. This could be in the FF parser or in the delivery mechanism to the instance of the decoder.

  2. The instance of the decoder is compromised.

The aritfacts in the picture look like I-frame artifacts, definitely in the transform coefficient domain.

If you're starting a video decoder and jumping into a stream that's already broadcasting, make sure you look for an I-frame to start up on. If you start on a P-frame, you'll see artifacts as well.

Not sure why other instances would be affected by one switching out. Perhaps there is some close-down logic that trashes the other instances?

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