[libav-bugs] [Bug 80] New: AAC+ Parametric Stereo decoding bug w/Winamp+shoutcast source(fhg encoder)

bugzilla-daemon at aruru.libav.org bugzilla-daemon at aruru.libav.org
Tue Nov 22 14:12:26 CET 2011


http://bugzilla.libav.org/show_bug.cgi?id=80

           Summary: AAC+ Parametric Stereo decoding bug w/Winamp+shoutcast
                    source(fhg encoder)
           Product: Libav
           Version: git HEAD
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: libavcodec
        AssignedTo: bugzilla at libav.org
        ReportedBy: mystica at gmail.com


Created attachment 37
  --> http://bugzilla.libav.org/attachment.cgi?id=37
wget output of a shoutcast stream 48k AAC+ Parametric Stereo

I notice a definite problem in the AAC+ decoder of libav, specifically the
Parametric Stereo bitstream produced by Winamp/Shoutcast's FHG encoder.  The
test stream is 48kbit.

It seems like the right channel is stuttering, producing repeated and echoy
output, which sounds quite bad. A visual of the waveform also shows definite
repeated peaks/troughs as if the signal was duplicated and mixed in with a
delay. 


mike at odin ~/www $ avconv -v 9 -loglevel 99 -i
aacp-ps-broken-bitstream-with-ICY-headers.aac test.wav
avconv version v0.7-1908-g0945edd, Copyright (c) 2000-2011 the Libav developers
  built on Nov 22 2011 02:54:05 with gcc 4.5.3
  configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64
--mandir=/usr/share/man --enable-shared --cc=x86_64-pc-linux-gnu-gcc
--enable-static --enable-gpl --enable-version3 --enable-postproc
--enable-avfilter --disable-debug --disable-doc --enable-libmp3lame
--enable-libfaac --enable-nonfree --enable-libvo-aacenc --enable-libtheora
--enable-libvorbis --enable-libx264 --enable-libxvid --enable-libdc1394
--disable-indev=oss --enable-x11grab --disable-outdev=oss --enable-frei0r
--enable-pthreads --enable-libgsm --enable-libdirac --enable-librtmp
--enable-libschroedinger --enable-libspeex --enable-libvpx --enable-libopenjpeg
--disable-altivec --disable-amd3dnow --disable-amd3dnowext --cpu=host
--enable-hardcoded-tables
  libavutil    51. 16. 0 / 51. 16. 0
  libavcodec   53. 22. 0 / 53. 22. 0
  libavformat  53. 15. 0 / 53. 15. 0
  libavdevice  53.  2. 0 / 53.  2. 0
  libavfilter   2. 13. 0 /  2. 13. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  52.  0. 0 / 52.  0. 0
[aac @ 0xf598a0] Probed with size=262144 and score=50
[aac @ 0xf5b760] err{or,}_recognition separate: 1; 1
[aac @ 0xf5b760] err{or,}_recognition combined: 1; 1
[aac @ 0xf5b760] Unsupported bit depth: 0
[aac @ 0xf5b760] channel element 2.4 is not allocated
[aac @ 0xf598a0] max_analyze_duration reached                                   
[aac @ 0xf598a0] Estimating duration from bitrate, this may be inaccurate       
Input #0, aac, from 'aacp-ps-broken-bitstream-with-ICY-headers.aac':            
  Duration: 00:01:01.21, bitrate: 45 kb/s
    Stream #0.0, 110, 1/28224000: Audio: aac, 44100 Hz, 2 channels (FC), s16,
45 kb/s
[pcm_s16le @ 0xf6b6c0] err{or,}_recognition separate: 1; 1
[pcm_s16le @ 0xf6b6c0] err{or,}_recognition combined: 1; 1
[aac @ 0xf5b760] err{or,}_recognition separate: 1; 1
[aac @ 0xf5b760] err{or,}_recognition combined: 1; 1
[aac @ 0xf5b760] Unsupported bit depth: 0
Output #0, wav, to 'test.wav':
  Metadata:
    encoder         : Lavf53.15.0
    Stream #0.0, 0, 1/44100: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411
kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (aac -> pcm_s16le)
Press ctrl-c to stop encoding
[aac @ 0xf5b760] channel element 2.4 is not allocated
Error while decoding stream #0:0                                                
size=    9984kB time=57.96 bitrate=1411.2kbits/s                                
video:0kB audio:9984kB global headers:0kB muxing overhead 0.000450%

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