[FFmpeg-trac] #2686(avcodec:open): Native AAC encoder collapses at high bitrates on some samples
FFmpeg
trac at avcodec.org
Sat Jul 20 21:02:21 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 Kamedo2):
Replying to [comment:60 klaussfreire]:
> Try this cutoff:
>
> {{{
> #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 tried, but isn't this cutoff strange? It sounds like the lowpass is
always 20kHz.
The problem of ffmpeg_aacvbr_pulse1.flac is solved by this.
I'm using current git head 54813 + aac-improvements-
wip-v2-rclookahead.2.patch + aacpsy.c Line 308
{{{
pctx->frame_bits = FFMIN(2560, chan_bitrate * AAC_BLOCK_SIZE_LONG /
ctx->avctx->sample_rate);
}}}
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2686#comment:61>
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