[FFmpeg-trac] #2686(avcodec:open): Native AAC encoder collapses at high bitrates on some samples
FFmpeg
trac at avcodec.org
Sun Jul 21 06:15:40 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):
I recommend psymodel.h line 24 to be:
{{{
#include "libavutil/libm.h"
#include "avcodec.h"
/** maximum possible number of bands */
#define PSY_MAX_BANDS 128
/** maximum number of channels */
#define PSY_MAX_CHANS 24
#define _AAC_CUTOFF(bit_rate,channels,sample_rate) (bit_rate ?
FFMIN3(FFMIN3( \
bit_rate/channels/2, \
3000 + bit_rate/channels/4, \
12000 + bit_rate/channels/16), \
20000, \
sample_rate / 2): (sample_rate / 2))
#define AAC_CUTOFF(s) ( \
(s->flags & CODEC_FLAG_QSCALE) \
? _AAC_CUTOFF(((int)(135000.0f*sqrtf(s->global_quality ?
s->global_quality/120.0f : 1.0f))), 2, s->sample_rate) \
: _AAC_CUTOFF(s->bit_rate, s->channels, s->sample_rate) \
)
}}}
In this way, I can set cutoff to VBR modes as well.
PSY_MAX_CHANS 24 is to accommodate NHK 22.2ch.
I notice that in -q:a 0.2 and -q:a 0.4, the lower freq is in trouble. It
sounds like a thunder far away.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2686#comment:70>
FFmpeg <http://ffmpeg.org>
FFmpeg issue tracker
More information about the FFmpeg-trac
mailing list