Difference between revisions of "Development/Tutorials/Debugging/Phonon"

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= Environment Variables =
{{Moved To Community | Guidelines_and_HOWTOs/Debugging }}
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:
<syntaxhighlight lang="bash">
Then run your program. The terminal will fill up with gobs of debugging output.
== Phonon-GStreamer debugging ==
=== Drawing a dot diagram ===
<syntaxhighlight lang="bash">
$ export GST_DEBUG_DUMP_DOT_DIR=/tmp
$ # run your program
$ dot -Tpng -oimage.png < /tmp/one-of-the-dot-files.dot
=== 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.
<syntaxhighlight lang="bash">
$ 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:
<!-- FIXME: We need a nice diagram -->
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:
<syntaxhighlight lang="bash">
$ 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:
<syntaxhighlight lang="bash">
$ 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 <pre>sudo apt-get build-dep phonon</pre>to be sure you have all dependencies installed.
<br />
<pre>sudo zypper si -d phonon</pre>
== Install git ==
In Kubuntu, Debian, etc.:<pre>sudo apt-get install git-core</pre>
In Archlinux:<pre>sudo pacman -Sy git</pre>
In Gentoo:<pre>sudo emerge -av dev-util/git</pre>
In OpenSuSE:<pre>sudo zypper install git</pre>
== 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<pre>ccache -M 2G</pre>
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 <tt>$HOME/.bashrc</tt>:
<syntaxhighlight lang="bash">
export PATH=$HOME/kde/bin:$PATH
export PATH=/usr/lib/ccache:$PATH
Reload your edited .bashrc:
<syntaxhighlight lang="bash">
source $HOME/.bashrc
NOTE: if you are not using the bash shell, edit your proper shell config file (<tt>~/.zshrc</tt> or <tt>~/.tcshrc</tt> or whatever it may be).
== Make KDE aware of Phonon’s location ==
<syntaxhighlight lang="bash">
echo 'export KDEDIR=$HOME/kde' >> $HOME/.kde/env/myenv.sh
echo 'export KDEDIRS=$KDEDIR' >> $HOME/.kde/env/myenv.sh
Some distributions call the above folder <tt>$HOME/.kde4/</tt>, such as OpenSuSE.
== Install locally==
Install in your $HOME dir):
<syntaxhighlight lang="bash">
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:
<syntaxhighlight lang="bash">
cd ~/kde/src/phonon
git pull
cd build && sudo make install
== Build locally from a tarball ==
This is 4.4.4 for example:
<syntaxhighlight lang="bash">
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

Revision as of 09:14, 5 August 2016

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