Doom9's Forum - View Single Post

Didée · 15th December 2002, 17:37

[smoke coming out of my head]

Thanks very much for clarification, sysKin.

I would lie if I'd say I understand it now completely

However, this was a pretty good example what silly assumptions sometimes may grow!
I took all the little hints that were dropped here, there and elsewhere by people with insight into XviD's technology, and tried to puzzle them together in a logical manner.
The result was crap.

But, sorry for being penetrant:

> If qpel is active, encoder just chooses a bigger range [of motion vectors]

>Qpel generally decreases compressability. Although it can find a
>better match, it usually doesn't 'correct' this match anyway,
>because the errors are too small. If there is no good match, qpel
>doesn't help much either - the amound of texture data is still similar

Reading that, I start even more wondering:
- Range is increased by qpel ???
- What IS the benefit of qpel? From your explanation, I understood that it OTOH decreases compressability, and OTOH doesn't help much ???

I thought it has to do with sub-pixel accuracy?

Pretty

now

Didée

15th December 2002, 17:37	#14 \| Link
Didée Registered User Join Date: Apr 2002 Location: Germany Posts: 5,391	[smoke coming out of my head] Thanks very much for clarification, sysKin. I would lie if I'd say I understand it now completely However, this was a pretty good example what silly assumptions sometimes may grow! I took all the little hints that were dropped here, there and elsewhere by people with insight into XviD's technology, and tried to puzzle them together in a logical manner. The result was crap. But, sorry for being penetrant: > If qpel is active, encoder just chooses a bigger range [of motion vectors] >Qpel generally decreases compressability. Although it can find a >better match, it usually doesn't 'correct' this match anyway, >because the errors are too small. If there is no good match, qpel >doesn't help much either - the amound of texture data is still similar Reading that, I start even more wondering: - Range is increased by qpel ??? - What IS the benefit of qpel? From your explanation, I understood that it OTOH decreases compressability, and OTOH doesn't help much ??? I thought it has to do with sub-pixel accuracy? Pretty now Didée __________________ - We´re at the beginning of the end of mankind´s childhood - My little flickr gallery. (Yes indeed, I do have hobbies other than digital video!) Last edited by Didée; 15th December 2002 at 17:40.