[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):

 There. Line 308:

 {{{
 pctx->frame_bits   = chan_bitrate * AAC_BLOCK_SIZE_LONG /
 ctx->avctx->sample_rate;
 }}}

 Must be

 {{{
 pctx->frame_bits   = FFMIN(3000, chan_bitrate * AAC_BLOCK_SIZE_LONG /
 ctx->avctx->sample_rate);
 }}}

 That is indeed said on the spec.

 Step 15 of subpart 4: Steps in threshold calculation: ''then bit
 allocation is limited to 0 < bit_allocation < 3000''. It seems they
 thought of it all.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2686#comment:48>
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