[libav-bugs] [Bug 336] New: DTS-ES 6.1 audio decoding issue (Libav for Windows, x86_64)

bugzilla-daemon at aruru.libav.org bugzilla-daemon at aruru.libav.org
Tue Jul 24 18:04:17 CEST 2012


http://bugzilla.libav.org/show_bug.cgi?id=336

           Summary: DTS-ES 6.1 audio decoding issue (Libav for Windows,
                    x86_64)
           Product: Libav
           Version: git HEAD
          Platform: X86
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: libavcodec
        AssignedTo: bugzilla at libav.org
        ReportedBy: tdskywalker at gmail.com


Using a 64-bit Windows nightly build of Libav from
http://win32.libav.org/win64/

Sample source:
https://dl.dropbox.com/u/37259775/libav/adistorsion/6point1_dts-es.mkv

avplay -i 6point1_dts-es.mkv -> distortion can be heard around 00:00:25
("Center Surround channel, Center Surround channel").

The issue is not reproducible with 32-bit nightlies (
http://win32.libav.org/win32/ ) or using a 64-bit build of avplay under OS X.

The issue is also not reproducible with non-DTS 6.1 samples, such as
https://dl.dropbox.com/u/37259775/libav/adistorsion/6point1_vorbis.mkv

---------------------------------------------------------------
Re-encoding the problem sample with avconv (64-bit Windows nightly):

avconv -i 6point1_dts-es.mkv 6point1_dts-es_d04c529_win64.wav

avconv version v0.8-2465-gd04c529, Copyright (c) 2000-2012 the Libav developers
  built on Jul 23 2012 19:28:30 with gcc 4.5.3 (Gentoo 4.5.3-r1 p1.0,
pie-0.4.5)
Input #0, matroska,webm, from '6point1_dts-es.mkv':
  Duration: 00:00:43.12, start: 0.000000, bitrate: N/A
    Stream #0.0(eng): Video: h264 (High), yuv420p, 1920x1080 [PAR 1:1 DAR
16:9], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
    Stream #0.1(eng): Audio: dca (DTS-HD MA), 48000 Hz, 6.1, s16, 768 kb/s
(default)
Output #0, wav, to '6point1_dts-es_d04c529_win64.wav':
  Metadata:
    encoder         : Lavf54.12.0
    Stream #0.0(eng): Audio: pcm_s16le, 48000 Hz, 6.1, s16, 5376 kb/s (default)
Stream mapping:
  Stream #0:1 -> #0:0 (dca -> pcm_s16le)
Press ctrl-c to stop encoding
size=   28273kB time=43.08 bitrate=5376.1kbits/s    

video:0kB audio:28273kB global headers:0kB muxing overhead 0.000235%
---------------------------------------------------------------

https://dl.dropbox.com/u/37259775/libav/adistorsion/6point1_dts-es_d04c529_win64.wav

With the encoded sample, the distortion can now be heard regardless of the
player and/or platform. The Center Surround channel itself is fine, but not the
Left/Right Surround channels (which also contain a distorted version of Center
Surround - it seems that the code which cancels the matrixed Center Surround
from Left/Right surround is not working properly in 64-bit Windows builds).

A HandBrake user was also able to reproduce the bug with a 64-bit Windows
nightly build of HandBrake and various DTS-HD MA 6.1 Blu-rays (Star Wars, Top
Gun), when downmixing to Stereo or 5.1. So it affects all DTS-ES 6.1 sources,
AFAICT.

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