Gabriel Bouvigne schrieb am Don, 01 Jun 2000:
> In the big (too big?) l3psycho_anal function, in the "determin final block
> type" section, is there a way to know if the frame is m/s or stereo? I mean,
> is there something like blocktype[chn] to know it?
>
>
> Regards,
>
> --
>
> Gabriel Bouvigne - France
> [EMAIL PROTECTED]
> icq: 12138873
>
> MP3' Tech: www.mp3-tech.org
Hi Gabriel,
the decision to encode in M/S or Stereo is made in lame.c:
/* use m/s gfc->stereo? */
check_ms_stereo = (gfp->mode == MPG_MD_JOINT_STEREO);
if (check_ms_stereo) {
/* make sure block type is the same in each channel */
check_ms_stereo =
(gfc->l3_side.gr[0].ch[0].tt.block_type==gfc->l3_side.gr[0].ch[1].tt.block_type)
&&
(gfc->l3_side.gr[1].ch[0].tt.block_type==gfc->l3_side.gr[1].ch[1].tt.block_type);
}
if (check_ms_stereo) {
/* ms_ratio = is like the ratio of side_energy/total_energy */
FLOAT8 ms_ratio_ave;
/* ms_ratio_ave = .5*(ms_ratio[0] + ms_ratio[1]);*/
ms_ratio_ave = .25*(gfc->ms_ratio[0] + gfc->ms_ratio[1]+
ms_ratio_prev + ms_ratio_next);
if ( (ms_ratio_ave <.35) && (.5*(gfc->ms_ratio[0]+gfc->ms_ratio[1])<.45) )
gfc->mode_ext = MPG_MD_MS_LR;
}
if (gfp->force_ms) gfc->mode_ext = MPG_MD_MS_LR;
Robert
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