[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            |
-------------------------------------+-------------------------------------

Comment (by Kamedo2):

 I inserted
 {{{
 av_log(NULL, AV_LOG_DEBUG, "\n cutoff=%d, lambda=%f, frame_bit_rate=%d,
 bandwidth=%d\n",cutoff,lambda,frame_bit_rate,bandwidth);
 }}}
 in aaccoder.c twoloop line 795, and found cutoff differs between different
 frames. I used -q:a 0.4, stereo 44.1kHz. I assume <99 cutoffs are the
 short blocks and 500< cutoffs are the long tonal blocks. The cutoff varies
 throughout the same music. 11.7k~13.6k for the short blocks, 11.5k~13.2k
 for the long blocks. (Calculated from the 25 raw examples below)

 {{{
  cutoff=77, lambda=47.000000, frame_bit_rate=46034, bandwidth=14508

  cutoff=614, lambda=47.000000, frame_bit_rate=45648, bandwidth=14412

  cutoff=76, lambda=47.000000, frame_bit_rate=45648, bandwidth=14412

  cutoff=612, lambda=47.000000, frame_bit_rate=45417, bandwidth=14354

  cutoff=76, lambda=47.000000, frame_bit_rate=45417, bandwidth=14354

  cutoff=532, lambda=47.000000, frame_bit_rate=37937, bandwidth=12484
     Last message repeated 1 times

  cutoff=538, lambda=47.000000, frame_bit_rate=38477, bandwidth=12619
     Last message repeated 1 times
 size=     242kB time=00:00:15.80 bitrate= 125.2kbits/s
  cutoff=68, lambda=47.000000, frame_bit_rate=39017, bandwidth=12754

  cutoff=544, lambda=47.000000, frame_bit_rate=39017, bandwidth=12754

  cutoff=548, lambda=47.000000, frame_bit_rate=39402, bandwidth=12850
     Last message repeated 1 times

  cutoff=551, lambda=47.000000, frame_bit_rate=39711, bandwidth=12927
     Last message repeated 1 times

  cutoff=554, lambda=47.000000, frame_bit_rate=39942, bandwidth=12985
     Last message repeated 1 times

  cutoff=69, lambda=47.000000, frame_bit_rate=40173, bandwidth=13043

  cutoff=556, lambda=47.000000, frame_bit_rate=40173, bandwidth=13043

  cutoff=69, lambda=47.000000, frame_bit_rate=40405, bandwidth=13101

  cutoff=558, lambda=47.000000, frame_bit_rate=40405, bandwidth=13101

  cutoff=561, lambda=47.000000, frame_bit_rate=40636, bandwidth=13159
     Last message repeated 1 times

  cutoff=562, lambda=47.000000, frame_bit_rate=40713, bandwidth=13178
     Last message repeated 1 times

  cutoff=71, lambda=47.000000, frame_bit_rate=41870, bandwidth=13467

  cutoff=574, lambda=47.000000, frame_bit_rate=41870, bandwidth=13467

  cutoff=79, lambda=47.000000, frame_bit_rate=47653, bandwidth=14913
     Last message repeated 1 times

  cutoff=78, lambda=47.000000, frame_bit_rate=46651, bandwidth=14662
     Last message repeated 1 times

  cutoff=76, lambda=47.000000, frame_bit_rate=45031, bandwidth=14257
     Last message repeated 1 times
 [output stream 0:0 @ 04adab60] EOF on sink link output stream 0:0:default.
 No more output streams to write to, finishing.

  cutoff=75, lambda=47.000000, frame_bit_rate=44337, bandwidth=14084
     Last message repeated 1 times

  cutoff=68, lambda=47.000000, frame_bit_rate=39711, bandwidth=12927
     Last message repeated 1 times
 [aac @ 04aaf580] Trying to remove 504 more samples than there are in the
 queue
 size=     253kB time=00:00:16.10 bitrate= 128.9kbits/s
 video:0kB audio:250kB subtitle:0 global headers:0kB muxing overhead
 1.475195%
 755 frames successfully decoded, 0 decoding errors
 [AVIOContext @ 04ad0440] Statistics: 30 seeks, 779 writeouts
 [AVIOContext @ 04d6f8a0] Statistics: 3123324 bytes read, 2 seeks
 }}}
 {{{
 ffmpeg54890g.exe -v 9 -loglevel 99 -i ffmpeg_aacvbr_pulse2.wav -c:a aac
 -strict experimental -q:a 0.4 ffmpeg_aacvbr_pulse2.mp4
 }}}
 I tried to automate it by batch script, including preserving the av_log
 output but somehow it freezes.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2686#comment:106>
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