Why does xVid and Divx allow compression squares?

[torok]

I believe that Windows Media 9 is a wrapper for Microsoft's MPEG-4 implimentation, right? So how come when the bitrate drops in with Windows Media, you don't get compression squares? With xVid and Divx anything less then totally transparent and you see those horrible squares all over the place. Why not smooth them over like Windows Media? Do people really prefer to see them?

[Teegedeck]

You can smooth them over - use postprocessing! XviD doesn't smooth automatically, you can choose how strongly you want your picture postprocessed or if you don't want it at all.

Also, your question is actually a bit like 'why doesn't XviD look like WindowsMedia?'. If you prefer the way WindowsMedia treats your input-video, fine. Just use it then; that's the good thing about having a choice.

WM9 is no MPEG4-implementation.

[RadicalEd]

Try Microsoft's ISO Mpeg 4 codec, I promise you you'll get worse looking results than XviD or DivX :_
WMV7/8/9 are not Mpeg 4, and thus can't be compared to it in this context.

[Teegedeck]

BTW, at bitrates that are too low for XviD I wouldn't use WM9 but RV10, or even better - an h.264-implementation.

[torok]

hehe, I figured I would piss some people off with that one. I swear I wasn't trolling though, I really am curious.

How do you do the smoothing during playback?

[Manao]

The MPEG-4 encoding scheme cuts the picture into blocks before encoding. That's why you get blocks. But thanks to that, you know where the blocks may appear. So you either have to check for a discontinuity at a block's boundary, or to assert that if a block is too compressed it is bound to be visible, and in both case, you'll smooth the boundary.

[communist]

Originally posted by torok
How do you do the smoothing during playback?
For XviD 1.0 ->
Start -> Programs -> XviD -> Configure Decoder -> Check both Deblocking options.
You can also call up the decoder config from with any decent media player and see before / after effect.

[bond]

Originally posted by RadicalEd
Try Microsoft's ISO Mpeg 4 codec, I promise you you'll get worse looking results than XviD or DivX :_
WMV7/8/9 are not Mpeg 4, and thus can't be compared to it in this context.microsofts "mpeg-4" codec isnt mpeg-4 compliant either!

[RadicalEd]

FALSE ADVERTISING. LAWSUIT.

[Selur]

just a thought:
wouldn't it be nice if there was a optional third pass in which xvid would reencode frames that got (visible) macroblocks and smooth in the part of the frame where the macroblock lies? (is this even possible?)

[PowerMacG4]

Originally posted by Selur
just a thought:
wouldn't it be nice if there was a optional third pass in which xvid would reencode frames that got (visible) macroblocks and smooth in the part of the frame where the macroblock lies? (is this even possible?)

That would most likely result in lots of flickering and not solve your problem at all. You can't smooth out a macroblock until post-processing.

[EthanoliX]

Originally posted by PowerMacG4
That would most likely result in lots of flickering and not solve your problem at all. You can't smooth out a macroblock until post-processing.

OK. Then let's try another "just a thought":

What about an optional third pass where XviD is trying to search for visible macroblocks and redistributing more bits to them, taken from less blocky frames?

Because for my personal taste visible macroblocks are the ugliest loss of detail.

[Asmodian]

I am just curious but why would this give you flickering? Having variable smoothing from frame to frame?

Maybe a better solution would be to just re-encode frames with obvious blocks at a lower quant (isn't this what Nandub did with the anti-s**t option?), or even using something like trellis (in that it changes the quant for individual blocks) that encodes blocks that have obvious boundaries at a lower quant?

EDIT: Oops, EthanoliX posted while I was typing.

[torok]

Originally posted by communist
For XviD 1.0 ->
Start -> Programs -> XviD -> Configure Decoder -> Check both Deblocking options.
You can also call up the decoder config from with any decent media player and see before / after effect.

Doesn't look like BetaPlayer or MVP support this smoothing, so that kind of makes the whole subject moot since I'm trying to make video for my handheld.