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analyze the gradient of the error surface to avoid a few checks in the quantizing noise shaper 

Originally committed as revision 2751 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2004-02-06 03:56:05 +00:00
parent 364a179749
commit de7ff1f774
1 changed files with 30 additions and 1 deletions
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31
libavcodec/mpegvideo.c
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@ -4941,6 +4941,7 @@ static int dct_quantize_refine(MpegEncContext *s, //FIXME breaks denoise?
DCTELEM *block, int16_t *weight, DCTELEM *orig,
int n, int qscale){
int16_t rem[64];
DCTELEM d1[64];
const int *qmat;
const uint8_t *scantable= s->intra_scantable.scantable;
const uint8_t *perm_scantable= s->intra_scantable.permutated;
@ -5061,10 +5062,31 @@ STOP_TIMER("init rem[]")
int nochange_score= best_score;
int best_coeff=0;
int best_change=0;
int run2, best_unquant_change;
int run2, best_unquant_change, analyze_gradient;
#ifdef REFINE_STATS
{START_TIMER
#endif
analyze_gradient = last_non_zero > 2 || s->avctx->quantizer_noise_shaping >= 3;
if(analyze_gradient){
#ifdef REFINE_STATS
{START_TIMER
#endif
for(i=0; i<64; i++){
int w= weight[i];
d1[i] = (rem[i]*w*w + (1<<(RECON_SHIFT+12-1)))>>(RECON_SHIFT+12);
}
#ifdef REFINE_STATS
STOP_TIMER("rem*w*w")}
{START_TIMER
#endif
s->dsp.fdct(d1);
#ifdef REFINE_STATS
STOP_TIMER("dct")}
#endif
}
if(start_i){
const int level= block[0];
int change, old_coeff;
@ -5141,6 +5163,13 @@ STOP_TIMER("init rem[]")
}
}else{
assert(ABS(new_level)==1);
if(analyze_gradient){
int g= d1[ scantable[i] ];
if(g && (g^new_level) >= 0)
continue;
}
if(i < last_non_zero){
int next_i= i + run2 + 1;
int next_level= block[ perm_scantable[next_i] ] + 64;