AC3 centre channel missing on local playback

[jochenf]

When playing video files with AC3 5.1 sound I cannot hear persons speaking. Only background noises. It looks like the centre channel is missing on downmix to stereo. I tried all possible settings for audio: alsa and pulseaudio driver, no downmix, downmix to stereo and downmix to dolby, always the centre channel is missing. Playing them with any other video player (vlc, mplayer) centre channel is present.

It is very difficult to cut videos while not hearing persons speaking, and it is impossible to make audio and video lipsync.

Any ideas what could be the cause of this?

Maybe the codec is not properly recognized by avidemux? When I open properties, it says Codec AC3 and channels stereo.

I'm using Debian Wheezy with Xfce desktop.

[mean]

It probably means the container is lying
Make sure you have a recent version of avidemux, i think now it probes to check the real channel layout

[jochenf]

I think it is not in a container. It is a stream output from ProjectX (loaded as external audio in Avidemux).

[mean]

could you share a ac3 sample ? What version of avidemux ?

[jochenf]

I tried to make a little sample from the mid of a 5.1 video and found that this was working right. I think I found the cause for my problems:

Usually I'm cutting and converting tv recordings. These recordings begin 5 minutes before the movie starts and end 10 minutes after movie end. I cut and convert them with the following steps:

• Demux the tv stream with ProjectX
• Load .m2v and .ac3 files into Avidemux
• Save them into .avi
• Load the .avi
• Cut the movie and convert it into MPEG4 AVC .mkv

Now the problem is that the recording begins with some 2.0 content and switches to 5.1 when the movie begins. Now the .avi has the information "2.0" in it's header, and this does not change when the movie begins. The whole .avi is then treated as 2.0.

Are there any workarounds to avoid this problem?

[mean]

If you use 2.6.x it should work (no need for projectX )

[jochenf]

Debian Wheezy has 2.5.6

[mean]

It's easy to compile, just run
bash bootStrap.bash --deb
and it will create the deb files

You can have it installed with 2.5, they dont conflict with each other

[jochenf]

It's not that easy. It compiled fine, but there is no audio driver for alsa, only oss. And it does not allow me to select an audio stream from the .ts file. It defaults to mp2.

[Jan Gruuthuse]

on ubuntu 11.10 I have these choices for audio device in avidemux: Main menu: Preferences: [Audio] AudioDevice:
Dummy
AlsaDefault <= get sound here
AlsaHw0
AlsaDmix
Oss
Jack
PulseAudioS
Esd
Have these installed on Ubuntu

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dpkg -l build-essential cmake fakeroot g++ gcc gettext liba52-0.7.4-dev libaften-dev libasound2-dev libdca-dev libdts-dev libfaac-dev libfaad-dev libfribidi-dev libglib2.0-dev libgtk2.0-dev libgtk-3-dev libmad0-dev libmp3lame-dev libpng12-dev libqt4-dev libqt4-opengl libqt4-opengl-dev libqt4-script libsamplerate0-dev libsdl-sound1.2-dev libsqlite3-dev libtwolame-dev libvdpau-dev libvorbis-dev libx264-dev libxml2-dev libxv-dev libxvidcore-dev make libopencore-amrwb-dev libopencore-amrnb-dev libvpx-dev pkg-config subversion yasm

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Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                        Version                     Description
+++-===========================-===========================-======================================================================
ii  build-essential             11.5ubuntu1                 Informational list of build-essential packages
ii  cmake                       2.8.5-1ubuntu1              cross-platform, open-source make system
ii  fakeroot                    1.17-1                      tool for simulating superuser privileges
ii  g++                         4:4.6.1-2ubuntu5            GNU C++ compiler
ii  gcc                         4:4.6.1-2ubuntu5            GNU C compiler
ii  gettext                     0.18.1.1-3ubuntu1           GNU Internationalization utilities
ii  liba52-0.7.4-dev            0.7.4-16                    library for decoding ATSC A/52 streams (development)
ii  libaften-dev                0.0.8+git20100105-0ubuntu1  audio AC3 encoder - development files
ii  libasound2-dev              1.0.24.1-0ubuntu10          shared library for ALSA applications -- development files
ii  libdca-dev                  0.0.5-4                     decoding library for DTS Coherent Acoustics streams (development)
ii  libdts-dev                  0.0.5-4                     backward compatibility place-holder for libdca
ii  libfaac-dev                 1.28-0ubuntu1               AAC audio encoder (development)
ii  libfaad-dev                 2.7-6ubuntu1                freeware Advanced Audio Decoder - development files
ii  libfribidi-dev              0.19.2-1                    Development files for FreeBidi library
ii  libglib2.0-dev              2.30.0-0ubuntu4             Development files for the GLib library
ii  libgtk-3-dev                3.2.0-0ubuntu6              development files for the GTK+ library
ii  libgtk2.0-dev               2.24.6-0ubuntu5             Development files for the GTK+ library
ii  libmad0-dev                 0.15.1b-5ubuntu1            MPEG audio decoder development library
ii  libmp3lame-dev              3.98.4-0ubuntu1             An MP3 encoding library (development)
ii  libopencore-amrnb-dev       0.1.2-1                     Adaptive Multi Rate speech codec - development files
ii  libopencore-amrwb-dev       0.1.2-1                     Adaptive Multi-Rate - Wideband speech codec - development files
ii  libpng12-dev                1.2.46-3ubuntu1.3           PNG library - development
ii  libqt4-dev                  4:4.7.4-0ubuntu8.3          Qt 4 development files
ii  libqt4-opengl               4:4.7.4-0ubuntu8.3          Qt 4 OpenGL module
ii  libqt4-opengl-dev           4:4.7.4-0ubuntu8.3          Qt 4 OpenGL library development files
ii  libqt4-script               4:4.7.4-0ubuntu8.3          Qt 4 script module
ii  libsamplerate0-dev          0.1.7-3ubuntu1              Development files for audio sample rate conversion
ii  libsdl-sound1.2-dev         1.0.3-3.1                   Development files for SDL_sound
ii  libsqlite3-dev              3.7.7-2ubuntu2              SQLite 3 development files
ii  libtwolame-dev              0.3.13-1                    MPEG Audio Layer 2 encoder (development files)
ii  libvdpau-dev                0.4.1-2ubuntu1              Video Decode and Presentation API for Unix (development files)
ii  libvorbis-dev               1.3.2-1ubuntu2.1            The Vorbis General Audio Compression Codec (development files)
ii  libvpx-dev                  0.9.6-1                     VP8 video codec (development files)
ii  libx264-dev                 2:0.116.2042+git178455c-1ub development files for libx264
ii  libxml2-dev                 2.7.8.dfsg-4ubuntu0.5       Development files for the GNOME XML library
ii  libxv-dev                   2:1.0.6-2                   X11 Video extension library (development headers)
ii  libxvidcore-dev             2:1.3.2-3                   Open source MPEG-4 video codec (development)
ii  make                        3.81-8.1ubuntu1             An utility for Directing compilation.
ii  pkg-config                  0.26-1ubuntu1               manage compile and link flags for libraries
ii  subversion                  1.6.12dfsg-4ubuntu5.1       Advanced version control system
ii  yasm                        1.1.0-1                     modular assembler with multiple syntaxes support

Select audio track for in/exclussion from main menu: Audio: Select Track

[jochenf]

I followed these instructions and ended in a compilation without sound drivers other than oss. Ubuntu instructions don't help me on Debian because Ubuntu packages are often very different from Debian.

I give up and wait until the debian package maintainer updates to 2.6, or someone makes 2.6 Debian packages for download.
Is there no launchpad ppa for avidemux 2.6?

[Jan Gruuthuse]

what the link says you're posted:

Requirement list (debian/ubuntu)

dpkg -l http://wiki.debian.org/dpkg checks the installed packages on your system
apt-get http://wiki.debian.org/apt-get
start with: update your package info

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sudo apt-get update
For each of the missing packages you select the appropriate command:

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sudo apt-get install build-essential
sudo apt-get install cmake
sudo apt-get install fakeroot
sudo apt-get install g++
sudo apt-get install gcc
sudo apt-get install gettext
sudo apt-get install liba52-0.7.4-dev
sudo apt-get install libaften-dev
sudo apt-get install libasound2-dev
sudo apt-get install libdca-dev
sudo apt-get install libdts-dev
sudo apt-get install libfaac-dev
sudo apt-get install libfaad-dev
sudo apt-get install libfribidi-dev
sudo apt-get install libglib2.0-dev
sudo apt-get install libgtk2.0-dev
sudo apt-get install libgtk-3-dev
sudo apt-get install libmad0-dev
sudo apt-get install libmp3lame-dev
sudo apt-get install libpng12-dev
sudo apt-get install libqt4-dev
sudo apt-get install libqt4-opengl
sudo apt-get install libqt4-opengl-dev
sudo apt-get install libqt4-script
sudo apt-get install libsamplerate0-dev
sudo apt-get install libsdl-sound1.2-dev
sudo apt-get install libsqlite3-dev
sudo apt-get install libtwolame-dev
sudo apt-get install libvdpau-dev
sudo apt-get install libvorbis-dev
sudo apt-get install libx264-dev
sudo apt-get install libxml2-dev
sudo apt-get install libxv-dev
sudo apt-get install libxvidcore-dev
sudo apt-get install make
sudo apt-get install libopencore-amrwb-dev
sudo apt-get install libopencore-amrnb-dev
sudo apt-get install libvpx-dev
sudo apt-get install pkg-config
sudo apt-get install subversion
sudo apt-get install yasm

[jochenf]

Yes, I installed all these packages from the wiki.

[Jan Gruuthuse]

some of those above are not in the wiki!
when you compiled, did you then install from folder /avidemux_2.6_branch_mean/debs , these debs in this order:
avidemux3-core-2.6.3-8###-Linux
avidemux3-plugins-COMMON-2.6.3-8###-Linux
avidemux3-qt4-2.6.3-8###-Linux
avidemux3-plugins-QT4-2.6.3-8###-Linux

[jochenf]

Yes I installed all these debs