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

FFmpeg trac at avcodec.org
Wed Oct 16 10:58:21 CEST 2013

#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            |

Comment (by klaussfreire):

 v7 patch is attached.

 It's not commitable or complete yet. I know it was the idea, but I ran out
 of time, and since you'll be free and needing improvements to test...

 This patch fixes some important bugs regarding RD limit computation in
 transients. It also has a more robust tonality boost (form factor in this
 patch) method, which accounts for what psy already does (I noticed it does
 its own bit). In essence, it was necessary to actually count nonzero
 lines. This, I believe, is mostly what was wasting bits on speech. Speech
 still takes more bits, but less.

 Mahler (brass I guess in general) still sounds artifacty. I think I know
 how to fix it (and it might indeed fix some other stuff). But I haven't
 had time to incur there.

 I haven't had time to see the sample rates issue. So maybe later, you've
 got it mostly done anyway ;)

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2686#comment:212>
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