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slight quality improvement ( < +0.04 PSNR) for high bitrate videos with trellis quantization

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Originally committed as revision 2300 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2003-09-24 19:45:57 +00:00
parent 98b0858e10
commit 34f60ee61b
1 changed files with 41 additions and 1 deletions
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42
libavcodec/mpegvideo.c
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@ -3997,7 +3997,7 @@ static int dct_quantize_trellis_c(MpegEncContext *s,
int last_i= 0;
int coeff[3][64];
int coeff_count[64];
int lambda, qmul, qadd, start_i, last_non_zero, i;
int lambda, qmul, qadd, start_i, last_non_zero, i, dc;
const int esc_length= s->ac_esc_length;
uint8_t * length;
uint8_t * last_length;
@ -4206,12 +4206,52 @@ static int dct_quantize_trellis_c(MpegEncContext *s,
}
}
dc= block[0];
last_non_zero= last_i - 1 + start_i;
memset(block + start_i, 0, (64-start_i)*sizeof(DCTELEM));
if(last_non_zero < start_i)
return last_non_zero;
if(last_non_zero == 0 && start_i == 0){
int best_level= 0;
int best_score= dc * dc;
for(i=0; i<coeff_count[0]; i++){
const int level= coeff[i][0];
int unquant_coeff, score, distoration;
if(s->out_format == FMT_H263){
if(level>0){
unquant_coeff= (level*qmul + qadd)>>3;
}else{
unquant_coeff= (level*qmul - qadd)>>3;
}
}else{ //MPEG1
if (level < 0) {
unquant_coeff = ((((-level) << 1) + 1) * qscale * ((int) s->inter_matrix[0])) >> 4;
unquant_coeff = -((unquant_coeff - 1) | 1);
} else {
unquant_coeff = ((( level << 1) + 1) * qscale * ((int) s->inter_matrix[0])) >> 4;
unquant_coeff = (unquant_coeff - 1) | 1;
}
}
unquant_coeff = (unquant_coeff + 4) >> 3;
unquant_coeff<<= 3 + 3;
distoration= (unquant_coeff - dc) * (unquant_coeff - dc);
score= distoration + last_length[UNI_AC_ENC_INDEX(0, level+64)]*lambda;
if(score < best_score){
best_score= score;
best_level= level;
}
}
block[0]= best_level;
if(best_level == 0)
last_non_zero=-1;
return last_non_zero;
}
i= last_i;
assert(last_level);
//FIXME use permutated scantable