Cause of video artifact/artefact

views:

135

answers:

+1 Q:

Cause of video artifact/artefact

Hi folks,

![alt text][1]

The above screenshot shows some artifacting which is occuring during a software decode of a .DV video file, compliant to SMPTE 314m...

The artefacting is believed to be cause by a AC/DC coefficient problem, is this likely?

Any information is appreciated.

+1 A:

Looks to me like you might not be decoding the frame compression correctly...

Adam Davis 2009-02-18 15:41:31

Also, All frames decode to this standard :(

Dave 2009-02-18 15:44:05

Ah, you are right. http://en.wikipedia.org/wiki/DV There is compression on each frame, though. Are you decompressing each frame correctly?

Adam Davis 2009-02-18 16:07:09

@DV is *all* I-Frames.

Steve Rowe 2009-02-18 16:15:23

@Steve - DV has intraframe compression, but according to wikipedia (which, of course, is an unassailable bastion of truth ;-) it doesn't not have interframe compression. Thus each frame is compressed individually, and does not depend on any other frame for information.

Adam Davis 2009-02-18 18:33:36

Spot on Adam Davis

Dave 2009-02-20 10:33:35

@Adam, that's all I-frames. P and B frames are the inter-frame compression frames.

Steve Rowe 2009-02-25 03:52:40

+2 A:

I'm not sure what the issue is. The blockiness would seem to indicate you are decoding the AC coefficients incorrectly. The good news is that it appears every macro block is being decoded incorrectly. If nothing else, they are too dark. Thus I would step through the decoding of a single block. Do the math by hand and then watch it decode in the debugger. See where the numbers diverge.

Steve Rowe 2009-02-18 16:20:00

I have various yCbCr -> RGB conversion methods, none color correct although some better than others.Thanks for the feedback regarding the method of correction though, I'll give it a try!

Dave 2009-02-20 09:43:12

If you figure it out, let us know what the problem was.

Steve Rowe 2009-02-25 03:51:44

ansaurus

tags:

views:

answers:

Cause of video artifact/artefact

related questions