[FFmpeg-trac] #2686(avcodec:open): Native AAC encoder collapses at high bitrates on some samples
FFmpeg
trac at avcodec.org
Fri Jul 19 06:56:31 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):
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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