Development/Tutorials/Debugging/Phonon

    From KDE TechBase
    Revision as of 10:59, 7 May 2011 by Apachelogger (talk | contribs) (can someone please move the install stuff somewhere else?!?!?!)

    Environment Variables

    In general, there is one easy way to give Phonon devs all the information they need to help fix your problem.

    Set these environment variables:

    $ export PHONON_DEBUG=5
    $ export PHONON_PULSEAUDIO_DEBUG=5
    $ export PHONON_VLC_DEBUG=5
    $ export PHONON_GST_DEBUG=5
    $ export PHONON_XINE_DEBUG=5
    

    Then run your program. The terminal will fill up with gobs of debugging output.

    Phonon-GStreamer debugging

    Even more verbose output

    Phonon-gst has some fancier debug options available. In addition to PHONON_GST_DEBUG, there is PHONON_GST_GST_DEBUG. Setting it to 8 or so will cause the gstreamer libraries to produce copious quantities of debug output. We're talking thousands of lines of what seems to be useless noise. Roughly 1% of it is useful, but the phonon-gst devs can easily decipher it and drill down to the important bits.

    Pulseaudio

    Pulseaudio and phonon try their hardest to get along. Sometimes, it doesn't work. Luckily, there is a way to test gstreamer and pulseaudio to see who is at fault.

    $ gst-launch filesrc location=/usr/share/sounds/KDE-Sys-Log-In.ogg ! decodebin2 ! audioresample ! audioconvert ! pulsesink
    $ gst-launch filesrc location=/usr/share/sounds/KDE-Sys-Log-In.ogg ! decodebin2 ! audioresample ! audioconvert ! alsasink
    

    If they both work flawlessly, blame Phonon-GStreamer.

    If the first works but the second doesn't, you might have an exotic sound setup that involves tweaking the alsasink parameters to reflect what pulseaudio does to alsa.

    If the second works but the first doesn't, you can blame pulseaudio.

    Another way to confirm this is by setting the PHONON_GST_AUDIOSINK environment variable. Setting it to e.g. "pulsesink" uses the pulseaudio sink.

    Recreating the phonon-gst pipeline

    Phonon-GStreamer creates predicable pipelines. In general, they look like this:


    filesrc -> decodebin2 -> queue -> audioresample -> audioconvert -> pulsesink
                       \
                        -> ffmpegcolorspace -> queue -> xvimagesink
    

    If the input stream isn't coming from a file, it is likely coming in via KIO which pipes it into an abstractmediastream. If pulseaudio isn't used, then replace pulsesink with something of alsasink, osssink, or somesuch.

    Recreating the playback stream of some video file can be done as such:

    $ gst-launch filesrc location=/path/to/video ! decdebin2 name=dec ! audioresample ! audioconvert ! pulsesink \
        dec. ! ffmpegcolorspace ! xvimagesink
    

    DVD playback is a bit different:

      (subpicture stream)
          /--->---\
    rsndvdbin -> dvdspu -> ffmpegcolorspace -> queue -> xvimagesink
          \-> queue -> audioresample -> audioconvert -> pulsesink
    

    This is built with the following:

    $ gst-launch rsndvdbin ! dvdspu ! ffmpegcolorspace ! queue ! xvimagesink \
        rsndvdbin0 ! dvdspu0.subpicture \
        rsndvdbin0 ! queue ! audioresample ! audioconvert ! pulsesink
    

    Building Phonon from source

    If you want to have a newer Phonon build than 4.4.3 which is currently shipped by most distributions in KDE 4.6, you can build from source (git). Phonon is now located on git.kde.org.

    Get Dependencies

    Deb-based distros, run

    sudo apt-get build-dep phonon

    to be sure you have all dependencies installed.


    OpenSuSE:

    sudo zypper si -d phonon

    Install git

    In Kubuntu, Debian, etc.:

    sudo apt-get install git-core

    In Archlinux:

    sudo pacman -Sy git

    In Gentoo:

    sudo emerge -av dev-util/git

    In OpenSuSE:

    sudo zypper install git

    Install ccache to speed up compilation

    Install the package from your distribution and set the size of the cache to 2 GB with the command

    ccache -M 2G

    This will take 2Gb of space in your local directory. Enable the use of ccache by adding it to your local .bashrc, described below.

    Define the PATH and local environment

    Append the following to $HOME/.bashrc:

        export PATH=$HOME/kde/bin:$PATH
        export PATH=/usr/lib/ccache:$PATH
        export LD_LIBRARY_PATH=$HOME/kde/lib:$LD_LIBRARY_PATH

    Reload your edited .bashrc:

        source $HOME/.bashrc

    NOTE: if you are not using the bash shell, edit your proper shell config file (~/.zshrc or ~/.tcshrc or whatever it may be).

    Make KDE aware of Phonon’s location

    echo 'export KDEDIR=$HOME/kde' >> $HOME/.kde/env/myenv.sh
    echo 'export KDEDIRS=$KDEDIR' >> $HOME/.kde/env/myenv.sh

    Some distributions call the above folder $HOME/.kde4/ , such as OpenSuSE.

    Install locally

    Install in your $HOME dir):

    mkdir $HOME/kde && cd kde && mkdir src && cd src
    
    git clone git://anongit.kde.org/phonon
    
    cd phonon && mkdir build && cd build
    
    cmake -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=debugfull $HOME/kde/src/phonon
    
    sudo make install

    To update your build, it's even easier:

    cd ~/kde/src/phonon
    
    git pull
    
    cd build && sudo make install

    Build locally from a tarball

    This is 4.4.4 for example:

    cd ~/kde/src/
    
    wget http://download.kde.org/download.php?url=stable/phonon/4.4.4/src/phonon-4.4.4.tar.bz2
    
    tar xf phonon-4.4.4.tar.bz2
    
    cd phonon-4.4.4 && mkdir build && cd build 
    
    cmake -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=debugfull $HOME/kde/src/phonon-4.4.4
    
    sudo make install