[Ffmpeg-cvslog] [ffmpeg]: r5417 - in /trunk: libavcodec/snow.c libavcodec/snow.h tests/ffmpeg.regression.ref tests/rotozoom.regression.ref

[Mike Melanson]

Romain DEGEZ wrote:
> lorenm at natsuki.mplayerhq.hu wrote:
> 
>> Author: lorenm
>> Date: Sun May 28 23:44:47 2006
>> New Revision: 5417
>>
>> Log:
>> Snow multiple reference frames
>> (bitstream is not backwards compatible, even if refs aren't used)
>> +    int mx_context= av_log2(2*ABS(left->mx - top->mx)) + 16*!!b->ref;
>> +    int my_context= av_log2(2*ABS(left->my - top->my)) + 16*!!b->ref;
> 
> 
> Wow, never see that.
> What does '!!' mean ?

I'm just guessing here, but I think that maybe:

   n = 16*!!b->ref

is equivalent to:

   if (b->ref)
     n = 16;
   else
     n = 0;

I think there's a langauge lawyer on the list who could confirm or deny.

-- 
	-Mike Melanson