[XviD-devel] somebody can tell me how to use dquant?

[Radek Czyz]

peter ross wrote:

Oh wait Pete, I think you're wrong here. IIRC, dquant is the 
differential from the last macroblock, not relative to frame's quant. 
Frame's quant (as written in the vop header) is really just initial 
quant for the very first macroblock.

Radek


> 
> On Mon, 27 Dec 2004 09:27:42 +0800 "???" <dengxiongshu at yulong.com>
> wrote:
> 
>>        Could  anyone tell me how to implement dquant?   how can I use 
>> dquant?  If dquant is not equal zero, is current macro's quant
>> equal to previous  macro's  quant add current macro's dquant? dquant is
> 
> 
> the dquant array is used to vary the level of quantization applied to
> each macroblock. the dquant value is added to the overall frame quantizer.
> see SetMacroblockQuants() within xvidcore/src/encoder.c. in pseudo code:
> 
>     macroblock[n].quant = frame_quant + dquant[n];
> 
> important: the mpeg-4 bitstream format restricts the extent to which the
> quantizer can be varied. MBSetDquant() within xvidcore/src/encoder.c
> takes care of this.
> 
>> to use to macro level rate control? xvid have not implement macro level
>> rate control,so I don't understand dquant is use in xvid ,it is for
>> future?
> 
> 
> dquant could be considered an optional feature of xvid. it is only used
> if an appropriate plugin is linked to xvidcore. at the moment, we only
> have one plugin that uses dquant. see 
> xvidcore/src/plugins/plugin_lumimasking.c
> 
> regards,
> -- pete
> 
> 
> _______________________________________________
> XviD-devel mailing list
> XviD-devel at xvid.org
> http://list.xvid.org/mailman/listinfo/xvid-devel
> 
>