[MPlayer-users] lavc vs. xvid (and improving lavc quality)

[Nico Sabbi]

Michael Niedermayer wrote:

>Hi
>
>On Monday 07 June 2004 08:09, D Richard Felker III wrote:
>[...]
>  
>
>>>>another solution is to get _latest_ libavcodec cvs and use
>>>>cmp=10:subcmp=10:mbcmp=10:dia=3 but this is very new and so might not
>>>>work as expected yet, theres also a coefficient in the code which still
>>>>needs to be finetuned or exported
>>>>        
>>>>
>>>Wow.  WOW.  Did I mention: _WOW_!  This is an _amazing_ improvement.
>>>
>>>You're my new deity for this week. :)
>>>      
>>>
>>WOW! What I'm impressed at is that Michael was able to please the
>>"block whiners" so fast! :)
>>
>>BTW, could we have an explanation of why the "noise preserving" sse
>>function is better?
>>    
>>
>sure
>
>first ill explain what nsse is, nsse is simple the sse comparisson function 
>with an additional term added which is the difference amount of the high freq 
>noise between the compared blocks
>so when the source material is noisy the motion estimation / macroblock 
>decision will favor noisy blocks, the trick here is that its much cheaper 
>bitrate wise to find some noisy block instead of a using a lower quantizer 
>and actually storing the exact noise
>
>so why does keeping the images slightly noisy help? there are at least 2 
>relatively obvious reasons 
>1. the noise masks the blocking artefacts, just try to add some noise during 
>decoding, the blocks should be less visible
>2. when compressing some area of nearly constant color u end up with areas of 
>exactly constant color and somewhat blocky edges between colors n and n+1, 
>the motion compensation for the next frame is now limited to only a few 
>possible blocks as many motion vectors will result in the same constant color 
>or same 2 with an edge in the middle, OTOH if the image is noisy then there 
>are many more different choices for the motion compensation so the image can 
>be represented more accurately
>
>[...]
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>

does chroma motion work well with your last patch to sse ?