[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
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             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 Kamedo2):

 I've got it. When the native aac encoder calcs a masking curve, almost
 inaudible sounds like 18kHz, 20kHz, 22kHz is taking into account, and
 audible sound like 14kHz is masked by the inaudibles. Add the inaudible
 noise above to the source sound and the encoded sound will be
 significantly degraded. I recommend that any signals above 16kHz is
 disregarded in psychoacoustic engines.

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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2686#comment:32>
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