ffmpeg fails to identify DTS WAV files.

Bug #305315 reported by Adam Buchbinder on 2008-12-04
Affects Status Importance Assigned to Milestone
ffmpeg (Ubuntu)

Bug Description

Consider any DTS WAV file from http://www.diatonis.com/downloads_dts_ac3.html. (They're quite large, which is why I'm not attaching one.) I can play them in mplayer, which uses libdca to decode them, without specifying any command-line options or forcing a particular codec. However, ffplay and ffmpeg assume that they're PCM WAV files, and output white noise. This version of ffmpeg supposedly does support DTS audio:

$ ffmpeg -formats 2>/dev/null|grep dts
  E adts ADTS AAC
 D dts raw dts

What I expected: I expected ffmpeg to decode the sound file as a DTS file, and ffplay to play it as one.

What happened: ffmpeg decoded/played it as a PCM WAV file, resulting in white noise.

ProblemType: Bug
Architecture: i386
DistroRelease: Ubuntu 8.10
Package: ffmpeg 3:0.svn20080206-12ubuntu3
SourcePackage: ffmpeg-debian
Uname: Linux 2.6.27-7-generic i686

Reinhard Tartler (siretart) wrote :

I've creating an upstream bugtask, but this still needs forwarding upstream.

See http://ffmpeg.org/bugreports.html for guidelines how to do that.

On further investigation it's already open upstream. This problem arises because the relevant file's "fmt " chunk specifies type 0x01 (it's in little-endian format, two bytes at offset 0x14), which is uncompressed PCM data.


$ hexdump -x diatonis_dts_secret-universe.wav -n 2 -s 0x14
0000014 0001

Using hexedit to change the bytes at offset 0x14 from 01 00 to 01 20 (0x2001 in little-endian format):

$ hexdump -x diatonis_dts_secret-universe.wav -n 2 -s 0x14
0000014 2001

The file now plays properly in ffplay, and ffmpeg can decode it properly.

I would consider this a problem with the file, but according to the following thread on ffmpeg-devel, it's standard for programs writing DTS audio to do so with a broken header to maintain compatibility with broken CD burning programs. There was a patch proposed, but it wasn't adopted at the time.


As an aside, there's a workaround which I had thought didn't work because I was specifying the options in the wrong order. Using "ffplay -f dts file.wav" or "ffmpeg -f dts -i file.wav output.ogg" skips the codec detection, and works properly.

Changed in ffmpeg:
importance: Undecided → Unknown
status: New → Unknown
Changed in ffmpeg:
status: Unknown → Confirmed

I should add that I'm leaving the task open even though it's about dealing with broken files, as (1) the broken files are near-universal--that is, it's apparently more common to find DTS files that claim to be Microsoft PCM than DTS files claiming to be DTS--and (2) mplayer has working detection code, which seems to indicate that it's at least possible.

Changed in ffmpeg-debian:
status: New → Confirmed
Changed in ffmpeg:
status: Confirmed → New
affects: ffmpeg-debian (Ubuntu) → ffmpeg (Ubuntu)
Changed in ffmpeg (Ubuntu):
importance: Undecided → Low
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package ffmpeg - 4:0.6~svn20100505-1ubuntu1

ffmpeg (4:0.6~svn20100505-1ubuntu1) maverick; urgency=low

  * merge from debian/experimental. remaining changes:
    - don't disable encoders
    - don't build against libfaad, libdirac and libopenjpeg (all in universe)

ffmpeg (4:0.6~svn20100505-1) experimental; urgency=low

  * update to new upstream. Closes: #569727
    - fixes various segfaults and other minor feature improvements
      Closes: #374931, #522449, #501891, #559712, #420231, #369127, #538082,
              #298095, #294422, #561553, #525385, #495274, #420230
      LP: #305286, #457106, #529200, #301723, #305315, #336479, #420230,
          #412063, #428912, #432181, #440591, #453732, #453732, #453732,
      #514259, #515243, #521472, #530186, #530186, #197842, #483317,
     #483317, #539407, #280098, #331255, #566107, #569823, #570305,
  * Fixup lintian overrides for new upstream snapshot
  * Bump Standards-Version to 3.8.4
  * Many upstream changes, see upstream Changelog for details
 -- Reinhard Tartler <email address hidden> Wed, 26 May 2010 00:01:17 +0200

Changed in ffmpeg (Ubuntu):
status: Confirmed → Fix Released
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