encoding artefacts, a unusual request

[puma.snyder]

Hi everybody
I have an unusual request. Im looking for some reference footage with encoding artifacts/errors using divx or any other codec.
Ive had one once, but cant find the clip anymore, it was like a trail of blocks in some parts of the screen, inside those blocks the motion was freezed, they seemed to overlap eachother, and it formed a visually very interesting pattern. Has anyone of you had this artifact or any other interesting looking encoding errors and could provide me with short samples of those, or with a guide on how to reproduce them (if this is possible)?

Thanks very much in advance.
greetz
p.snyder

[UncasMS]

divx 3.11 produced theses macroblock glitches quite often for me when using nandub and NO A N T I S H I T option.

reproducing them will be difficult, providing you with a screenshot or sample should be possible.

[puma.snyder]

thanks UncasMS

that would be fantastic.

[Enchanter]

Re: encoding artefacts, a unusual request

Originally posted by puma.snyder
Hi everybody
I have an unusual request. Im looking for some reference footage with encoding artifacts/errors using divx or any other codec.
Ive had one once, but cant find the clip anymore, it was like a trail of blocks in some parts of the screen, inside those blocks the motion was freezed, they seemed to overlap eachother, and it formed a visually very interesting pattern. Has anyone of you had this artifact or any other interesting looking encoding errors and could provide me with short samples of those, or with a guide on how to reproduce them (if this is possible)?

That as got to be one VERY VERY bad artifact . . .

As UncasMS said, you can reproduce artifacts using DivX 3.11 (though it is unlikely to end up as bad as what you described). Using some filters, do the following to increase chances of DivX 3.11 artifacts occuring:
1. Increase the sharpness of the video considerably
2. Increase the Colour Saturation greatly (animation would be the perfect candidate for this given the prominence of solid colours in the videos)
3. Use very low bitrate (300kbps or lower)

[UncasMS]

here is what happend quite often when nandub was used with divx3 (that's why i always used ms v2 myself )

[Batman]

You may be able to reproduce "Mosquito noise" in XVID using low bitrates.

Also search the doom9.org forums for "mosquito noise" and "macroblocks"----that should provide you with a lot of posts concerning this problem and potential solutions.