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

FFmpeg trac at avcodec.org
Mon Jul 22 19:20:47 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            |
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Comment (by klaussfreire):

 Replying to [comment:89 Kamedo2]:
 > You seems to be using the heuristics that transients HF components are
 loud and tonal HF components are quiet.

 No, I let psy detect the transients. The only heuristic, is that I attempt
 to encode a little bit more of the HF with decreased quality.

 Ie, from 0-cutoff, normal quantization. From cutoff-cutoff * 1.2, coarse
 (progressively coarser in fact) quantization. Now, I let bit allocation
 zero out beyond 1.2. I may have to force it to avoid the artifacts you
 mention.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2686#comment:90>
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