Severe sound problem playing some aac files

Bug #575798 reported by Matthew Tompsett on 2010-05-05
22
This bug affects 4 people
Affects Status Importance Assigned to Milestone
faad2 (Ubuntu)
Undecided
Unassigned

Bug Description

Binary package hint: alsa-base

When playing some aac files (.m4a extension) in Lucid Lynx the sound is corrupted so that every split second there is a high pitched screeching noise and skipping. These files play perfectly in Karmic, Arch with all packages updated, and Windows. The files also play fine when played with XBMC and Aqualung, but exhibit the described problem when played with Rhythmbox, Totem, VLC and Audacious. I don't know what package exactly this bug affects so I'm going to tag it to alsa as it's a sound problem. I am attaching a clip from one of the offending files here http://drop.io/lwx4fgt. To reproduce the bug download the file and play it in Totem/VLC/Rhythmbox. This is quite an annoying bug as about 10% of my music library seems to be affected.

Matt

xxx@xxx:~$ apt-cache policy alsa-base
alsa-base:
  Installed: 1.0.22.1+dfsg-0ubuntu3
  Candidate: 1.0.22.1+dfsg-0ubuntu3
  Version table:
 *** 1.0.22.1+dfsg-0ubuntu3 0
        500 http://archive.ubuntu.com/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status

xxx@xxx:~$ lsb_release -rd
Description: Ubuntu 10.04 LTS
Release: 10.04

If other audio media types playback fine, this really isn't an alsa
issue. Please triage it against the appropriate audio player you're
using.

Matthew Tompsett (matthewbpt) wrote :

I don't know what to put it against, it happens in most audio players including Rhythmbox, Totem and VLC, It doesn't happen with XBMC or Aqualung. Here's a sample file which is affected http://drop.io/lwx4fgt , this file plays fine in previous versions of Ubuntu, and in other OS's, but won't play in Ubuntu in the mentioned players. Do they all use the same shared library to decode aac?

description: updated
Matthew Tompsett (matthewbpt) wrote :

I started a thread in the forum about the bug http://ubuntuforums.org/showthread.php?t=1473550

affects: alsa-driver (Ubuntu) → ffmpeg (Ubuntu)
Doug McMahon (mc3man) wrote :

I believe the issue here is files encoded with the Main aac profile will not decode properly in lucid, though they will in karmic and earlier.
 The same behavior is seen with a compiled mplayer - so that seems to remove the repo libfaad2 as cause.

On Thu, May 06, 2010 at 03:36:33 (CEST), Doug McMahon wrote:

> I believe the issue here is files encoded with the Main aac profile

please attach such files to this bug so that we can verify that claim.

Matthew Tompsett (matthewbpt) wrote :

> please attach such files to this bug so that we can verify that claim.

Here's a sample file which doesn't play correctly.

Matt

Doug McMahon (mc3man) wrote :

If wished to reproduce
edit the gstreamer profile for aac to encode to Main ( aac profile=1
and encode a track

While the gstreamer profile now properly defaults to LC, previously it was set to Main, don't recollect if change occurred in Karmic or was done in lucid

Only ffplay and mplayer -ac ffaac will properly decode.

Take that same track to karmic or earlier and all players will decode including mplayer which uses internal faad decoder

Matthew Tompsett (matthewbpt) wrote :

This is quite a severe problem for me as I have encoded hundreds of files in previous versions of Ubuntu using gstreamer and all these files are now useless to me in Lucid.

Doug McMahon (mc3man) wrote :

> Matthew Tompsett wrote
>This is quite a severe problem for me as I have encoded hundreds of files in previous versions of Ubuntu using gstreamer and all these files are now useless to me in Lucid.

I do feel bad for you - I guess this issue is somewhat mooted by the fact that almost no encoders use Main@1 for aac anymore and haven't for quite some time.

The notable exception to this is in 8.04 which continues to use Main@1 thru gstreamer - why this was never fixed is beyond me - faac has had a default to Main@2 (LC) for quite some time (predating 8.04 I'm sure

Why 10.04 can't handle these files is unknown to me - maybe a buffers issue - and though this has nothing to do with ffmpeg, pulse or any player in particular going to confirm anyway, maybe an explain will arrive, maybe not...

Changed in ffmpeg (Ubuntu):
status: New → Confirmed
Reinhard Tartler (siretart) wrote :

I can confirm the observation in comment #7. This means that the problem is not in ffmpeg, since both ffplay and mplayer when using ffaac play back that file properly.

However when using mplayer with libfaad, playback is distorted. Therefore, I'm reassigning to the correct package.

The decoding library which gstreamer and gstreamer based applications cannot be controlled in the ffmpeg package, but must be done in the respective media players. Note that mplayer itself defaults to libfaad, since in most cases, it does a better job.

affects: ffmpeg (Ubuntu) → faad2 (Ubuntu)
Doug McMahon (mc3man) wrote :

While I forgot that the lucid mplayer uses the system ffmpeg libs - still don't see the connection to the faad2 package in lucid (libfaad2
It's my understanding that mplayer uses it's own internal faad decoder even in it's present lucid build.

This can be seen by removing libfaad2 (no faad2 libs installed whatsoever) - mplayer by default still decodes aac thru faad (internal) and does LC properly while Main contines to be the issue.

Further - as a small test the other day I built vlc 1.0.6 on lucid statically linked to faad2 -2.6.1 (source used in karmic)

It plays aac LC files fine, exhibited the same (mis)behavior with aac Main

Reinhard Tartler (siretart) wrote :

On Mon, May 10, 2010 at 01:13:23 (CEST), Doug McMahon wrote:

> While I forgot that the lucid mplayer uses the system ffmpeg libs - still don't see the connection to the faad2 package in lucid (libfaad
> It's my understanding that mplayer uses it's own internal faad decoder even in it's present lucid build.

In order to playback aac, mplayer has 3 options:

 - libavcodec (called ffaac)
 - system libfaad2 (faad2)
 - internal copy of faad2 (internal faad)

According to the analysis pasted above, the problem cannot be reproduced
with the attached testfile and the decoder shipped by the ubuntu
libavcodec package.

In ubuntu we generally avoid internal library copies, i.e. if mplayer
indeed uses the internal faad over the system libfaad2, then this would
be a (seperate) bug against the mplayer package, which should be fixed.

> This can be seen by removing libfaad2 (no faad2 libs installed
> whatsoever) - mplayer by default still decodes aac thru faad (internal)
> and does LC properly while Main contines to be the issue.

which indicates that the internal copy of faad in mplayer inhibits the
same problem. not very surprising.

> Further - as a small test the other day I built vlc 1.0.6 on lucid
> statically linked to faad2 -2.6.1 (source used in karmic)
>
> It plays aac LC files fine, exhibited the same (mis)behavior with aac
> Main

another indication that the libfaad2 package fails to playback aac main

thanks for your analysis!

--
Gruesse/greetings,
Reinhard Tartler, KeyID 945348A4

Matthew Tompsett (matthewbpt) wrote :

>> Further - as a small test the other day I built vlc 1.0.6 on lucid
>> statically linked to faad2 -2.6.1 (source used in karmic)
>>
>> It plays aac LC files fine, exhibited the same (mis)behavior with aac
>> Main
>
> another indication that the libfaad2 package fails to playback aac main
>
> thanks for your analysis!

I think the point Doug is making here is that in Karmic vlc doesn't fail to play the file, but taking the karmic faad source and building it into vlc in Lucid results in the file being unplayable. If the file plays fine in Karmic and not in Lucid using the same faad source then faad isn't the problem ... ?

Josh (algorithm007) wrote :

I have the same issue...However, If I use amarok, it plays the m4a files properly.

However, any Gnome based media player refuses to play the m4a files without
skipping and high pitched noise. It is soo annoying, as all my music is in this
format!!

Richard Blum (richard-a-blum) wrote :

I just happened on the same bug, too. Any progress on it? I have many .m4a files that I created in an earlier version of Ubuntu, and they won't play in rhythmbox, but they will play in amarok.

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