#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):
Replying to [comment:60 klaussfreire]:
> {{{
> #define _AAC_CUTOFF(bit_rate,channels,sample_rate) (bit_rate ?
FFMIN3(FFMIN3( \
> bit_rate/channels, \
> 3000 + bit_rate/channels/2, \
> 16000 + bit_rate/channels/8), \
> 20000, \
> sample_rate / 2): (sample_rate / 2))
> #define AAC_CUTOFF(s) ( \
> (s->flags & CODEC_FLAG_QSCALE) \
> ? _AAC_CUTOFF(s->bit_rate, s->channels, s->sample_rate) \
> : _AAC_CUTOFF((int)(s->bit_rate * (s->global_quality ?
s->global_quality : 120) / 120.0), 2, s->sample_rate) \
> )
> }}}
>
> I find it works better, the other was was pretty dull for 64k/ch, which
ought to be transparent for AAC. This one also works on VBR.
The high cutoff causes trouble for whitenoise.flac below 55kbps.
And I'm almost certain 16kHz is optimal at 128kbps stereo.
http://d.hatena.ne.jp/kamedo2/20120221/1329845124
http://d.hatena.ne.jp/kamedo2/20120729/1343545890
[[Image(http://i43.tinypic.com/cmhx3.png)]]
[[Image(http://i39.tinypic.com/2ecdv0o.png)]]
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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2686#comment:69>
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