[FFmpeg-trac] #2686(avcodec:open): Native AAC encoder collapses at high bitrates on some samples

[FFmpeg]

#2686: Native AAC encoder collapses at high bitrates on some samples
-------------------------------------+-------------------------------------
             Reporter:  Kamedo2      |                    Owner:
                 Type:  defect       |                   Status:  open
             Priority:  normal       |                Component:  avcodec
              Version:  git-master   |               Resolution:
             Keywords:  aac          |               Blocked By:
  regression                         |  Reproduced by developer:  1
             Blocking:               |
Analyzed by developer:  0            |
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Comment (by klaussfreire):

 PS: In aaccoder.c:1007, you can change

 {{{
 //if (mb >= ESC_BT) break;
 }}}

 Into

 {{{
 if (mb >= ESC_BT && sce->sf_idx[w*16+g] <= minscaler) break;
 }}}

 I think that could help, because, I believe, those bitrate peaks are due
 to abuse of ESC_BT bands. And that could also be the reason why some faint
 sounds get lost even at high Q, because AAC enforces a maximum dynamic
 range in scalers, and abusing of ESC_BT bands pushes that dynamic range in
 detriment of faint sounds.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2686#comment:185>
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