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Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Phonon
Matthias Kretz
former KView maintainer
work on aRts and KDE Multimedia
Student of Physics and Computer Science at the University of Heidelberg
KDE Multimedia Meeting 2006
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Outline
What is Phonon?
Design of PhononCore ClassesCode ExamplesUser Visible FeaturesHow to Write a Backend
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Multimedia API
I task-oriented designI 80/20I easy multimedia developmentI no “competition” for GStreamer/NMM like media
frameworksI in KDE SVN: trunk/KDE/kdelibs/phonon (or
branches/work/kdelibs4_snapshot/phonon)
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Multimedia API
I task-oriented designI 80/20I easy multimedia developmentI no “competition” for GStreamer/NMM like media
frameworksI in KDE SVN: trunk/KDE/kdelibs/phonon (or
branches/work/kdelibs4_snapshot/phonon)
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Multimedia API
I task-oriented designI 80/20I easy multimedia developmentI no “competition” for GStreamer/NMM like media
frameworksI in KDE SVN: trunk/KDE/kdelibs/phonon (or
branches/work/kdelibs4_snapshot/phonon)
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Multimedia API
I task-oriented designI 80/20I easy multimedia developmentI no “competition” for GStreamer/NMM like media
frameworksI in KDE SVN: trunk/KDE/kdelibs/phonon (or
branches/work/kdelibs4_snapshot/phonon)
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Multimedia API
I task-oriented designI 80/20I easy multimedia developmentI no “competition” for GStreamer/NMM like media
frameworksI in KDE SVN: trunk/KDE/kdelibs/phonon (or
branches/work/kdelibs4_snapshot/phonon)
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Motivationthe user’s perspective
I A user should be able to playback any media withoutconfiguration steps
I “power users” want great flexibilityI additional multimedia hardware should be available
to all applications without any further stepsI users need to decide what device to use for what
purpose/programI KDE should not get in the way of “media producers”
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Motivationthe user’s perspective
I A user should be able to playback any media withoutconfiguration steps
I “power users” want great flexibilityI additional multimedia hardware should be available
to all applications without any further stepsI users need to decide what device to use for what
purpose/programI KDE should not get in the way of “media producers”
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Motivationthe user’s perspective
I A user should be able to playback any media withoutconfiguration steps
I “power users” want great flexibilityI additional multimedia hardware should be available
to all applications without any further stepsI users need to decide what device to use for what
purpose/programI KDE should not get in the way of “media producers”
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Motivationthe user’s perspective
I A user should be able to playback any media withoutconfiguration steps
I “power users” want great flexibilityI additional multimedia hardware should be available
to all applications without any further stepsI users need to decide what device to use for what
purpose/programI KDE should not get in the way of “media producers”
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Motivationthe user’s perspective
I A user should be able to playback any media withoutconfiguration steps
I “power users” want great flexibilityI additional multimedia hardware should be available
to all applications without any further stepsI users need to decide what device to use for what
purpose/programI KDE should not get in the way of “media producers”
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Motivationthe developer’s perspective
I Qt/KDE style APII developers need APIs that are straightforward, easy
to use and understandI applications need a multimedia API that works on
UNIX systems (including OS X) and WindowsI ABI changes should not hinder KDE from using the
newest version of some media framework
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Motivationthe developer’s perspective
I Qt/KDE style APII developers need APIs that are straightforward, easy
to use and understandI applications need a multimedia API that works on
UNIX systems (including OS X) and WindowsI ABI changes should not hinder KDE from using the
newest version of some media framework
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Motivationthe developer’s perspective
I Qt/KDE style APII developers need APIs that are straightforward, easy
to use and understandI applications need a multimedia API that works on
UNIX systems (including OS X) and WindowsI ABI changes should not hinder KDE from using the
newest version of some media framework
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Motivationthe developer’s perspective
I Qt/KDE style APII developers need APIs that are straightforward, easy
to use and understandI applications need a multimedia API that works on
UNIX systems (including OS X) and WindowsI ABI changes should not hinder KDE from using the
newest version of some media framework
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Phonon Backends
Xine
Application
Phonon
Phonon−Xine
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Phonon Backends
GStreamer
Application
Phonon
Phonon−GStreamer
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Phonon Backends
NMM
Application
Phonon
Phonon−NMM
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Outline
What is Phonon?
Design of PhononCore ClassesCode ExamplesUser Visible FeaturesHow to Write a Backend
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
The Core Classes
AudioOutput
VideoOutput
send to
send to
AudioEffect
VideoEffect
VideoPath
AudioPathprocess audio in
process video in
MediaObjectMediaObject
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
The Core Classes
AudioOutput
VideoOutput
send to
send to
AudioEffect
VideoEffect
VideoPath
AudioPathprocess audio in
process video in
MediaObjectMediaObject
VideoPath
AudioPathprocess audio in
process video in
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
The Core Classes
AudioOutput
VideoOutput
send to
send to
AudioEffect
VideoEffect
VideoPath
AudioPathprocess audio in
process video in
MediaObjectMediaObject
VideoPath
AudioPathprocess audio in
process video in
AudioOutput
VideoOutput
send to
send to
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
The Core Classes
AudioOutput
VideoOutput
send to
send to
AudioEffect
VideoEffect
VideoPath
AudioPathprocess audio in
process video in
MediaObjectMediaObject
VideoPath
AudioPathprocess audio in
process video in
AudioEffect
VideoEffect
AudioOutput
VideoOutput
send to
send to
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
A Glance at the Phonon Classes
I BackendCapabilitiesI AbstractMediaProducer
I MediaObjectI ByteStreamI AvCapture
I AbstractAudioOutputI AudioOutputI AudioDataOutput
I AbstractVideoOutputI VideoWidgetI VideoDataOutput
I AudioPathI VideoPathI AudioEffect
I VolumeFaderEffect
I VideoEffect
I NameDescriptionTupleI AudioOutputDeviceI AudioCaptureDeviceI VideoOutputDeviceI VideoCaptureDeviceI AudioEffectDescriptionI VideoEffectDescription
I Ui::VideoWidgetI Ui::SeekSliderI Ui::VolumeSliderI Ui::MediaControlsI Ui::EffectWidget
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
A Glance at the Phonon Classes
I BackendCapabilitiesI AbstractMediaProducer
I MediaObjectI ByteStreamI AvCapture
I AbstractAudioOutputI AudioOutputI AudioDataOutput
I AbstractVideoOutputI VideoWidgetI VideoDataOutput
I AudioPathI VideoPathI AudioEffect
I VolumeFaderEffect
I VideoEffect
I NameDescriptionTupleI AudioOutputDeviceI AudioCaptureDeviceI VideoOutputDeviceI VideoCaptureDeviceI AudioEffectDescriptionI VideoEffectDescription
I Ui::VideoWidgetI Ui::SeekSliderI Ui::VolumeSliderI Ui::MediaControlsI Ui::EffectWidget
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
A Glance at the Phonon Classes
I BackendCapabilitiesI AbstractMediaProducer
I MediaObjectI ByteStreamI AvCapture
I AbstractAudioOutputI AudioOutputI AudioDataOutput
I AbstractVideoOutputI VideoWidgetI VideoDataOutput
I AudioPathI VideoPathI AudioEffect
I VolumeFaderEffect
I VideoEffect
I NameDescriptionTupleI AudioOutputDeviceI AudioCaptureDeviceI VideoOutputDeviceI VideoCaptureDeviceI AudioEffectDescriptionI VideoEffectDescription
I Ui::VideoWidgetI Ui::SeekSliderI Ui::VolumeSliderI Ui::MediaControlsI Ui::EffectWidget
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
A Glance at the Phonon Classes
I BackendCapabilitiesI AbstractMediaProducer
I MediaObjectI ByteStreamI AvCapture
I AbstractAudioOutputI AudioOutputI AudioDataOutput
I AbstractVideoOutputI VideoWidgetI VideoDataOutput
I AudioPathI VideoPathI AudioEffect
I VolumeFaderEffect
I VideoEffect
I NameDescriptionTupleI AudioOutputDeviceI AudioCaptureDeviceI VideoOutputDeviceI VideoCaptureDeviceI AudioEffectDescriptionI VideoEffectDescription
I Ui::VideoWidgetI Ui::SeekSliderI Ui::VolumeSliderI Ui::MediaControlsI Ui::EffectWidget
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
A Glance at the Phonon Classes
I BackendCapabilitiesI AbstractMediaProducer
I MediaObjectI ByteStreamI AvCapture
I AbstractAudioOutputI AudioOutputI AudioDataOutput
I AbstractVideoOutputI VideoWidgetI VideoDataOutput
I AudioPathI VideoPathI AudioEffect
I VolumeFaderEffect
I VideoEffect
I NameDescriptionTupleI AudioOutputDeviceI AudioCaptureDeviceI VideoOutputDeviceI VideoCaptureDeviceI AudioEffectDescriptionI VideoEffectDescription
I Ui::VideoWidgetI Ui::SeekSliderI Ui::VolumeSliderI Ui::MediaControlsI Ui::EffectWidget
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
A Glance at the Phonon Classes
I BackendCapabilitiesI AbstractMediaProducer
I MediaObjectI ByteStreamI AvCapture
I AbstractAudioOutputI AudioOutputI AudioDataOutput
I AbstractVideoOutputI VideoWidgetI VideoDataOutput
I AudioPathI VideoPathI AudioEffect
I VolumeFaderEffect
I VideoEffect
I NameDescriptionTupleI AudioOutputDeviceI AudioCaptureDeviceI VideoOutputDeviceI VideoCaptureDeviceI AudioEffectDescriptionI VideoEffectDescription
I Ui::VideoWidgetI Ui::SeekSliderI Ui::VolumeSliderI Ui::MediaControlsI Ui::EffectWidget
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
A Glance at the Phonon Classes
I BackendCapabilitiesI AbstractMediaProducer
I MediaObjectI ByteStreamI AvCapture
I AbstractAudioOutputI AudioOutputI AudioDataOutput
I AbstractVideoOutputI VideoWidgetI VideoDataOutput
I AudioPathI VideoPathI AudioEffect
I VolumeFaderEffect
I VideoEffect
I NameDescriptionTupleI AudioOutputDeviceI AudioCaptureDeviceI VideoOutputDeviceI VideoCaptureDeviceI AudioEffectDescriptionI VideoEffectDescription
I Ui::VideoWidgetI Ui::SeekSliderI Ui::VolumeSliderI Ui::MediaControlsI Ui::EffectWidget
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
A Glance at the Phonon Classes
I BackendCapabilitiesI AbstractMediaProducer
I MediaObjectI ByteStreamI AvCapture
I AbstractAudioOutputI AudioOutputI AudioDataOutput
I AbstractVideoOutputI VideoWidgetI VideoDataOutput
I AudioPathI VideoPathI AudioEffect
I VolumeFaderEffect
I VideoEffect
I NameDescriptionTupleI AudioOutputDeviceI AudioCaptureDeviceI VideoOutputDeviceI VideoCaptureDeviceI AudioEffectDescriptionI VideoEffectDescription
I Ui::VideoWidgetI Ui::SeekSliderI Ui::VolumeSliderI Ui::MediaControlsI Ui::EffectWidget
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Outline
What is Phonon?
Design of PhononCore ClassesCode ExamplesUser Visible FeaturesHow to Write a Backend
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackthe simplest case
SimplePlayer
SimplePlayer* player = new SimplePlayer;player->play( "file:///home/user/song.ogg" );
seek/pause/stop
player->seek( milliseconds );player->pause();player->stop();
volume
float volume = player->volume();volume *= 0.5;player->setVolume( volume );
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackthe simplest case
SimplePlayer
SimplePlayer* player = new SimplePlayer;player->play( "file:///home/user/song.ogg" );
seek/pause/stop
player->seek( milliseconds );player->pause();player->stop();
volume
float volume = player->volume();volume *= 0.5;player->setVolume( volume );
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackthe simplest case
SimplePlayer
SimplePlayer* player = new SimplePlayer;player->play( "file:///home/user/song.ogg" );
seek/pause/stop
player->seek( milliseconds );player->pause();player->stop();
volume
float volume = player->volume();volume *= 0.5;player->setVolume( volume );
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackwith more control
define the output
output = new AudioOutput;output->setCategory( Phonon::MusicCategory );path1 = new AudioPath;path1->addOutput( output );
AudioOutputAudioPathMediaObject
AudioOutputAudioPath
simple MediaObject use
media1 = new MediaObject;media1->addAudioPath( path1 );media1->setUrl( "file:///home/user/song.ogg" );media1->play();
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackwith more control
define the output
output = new AudioOutput;output->setCategory( Phonon::MusicCategory );path1 = new AudioPath;path1->addOutput( output );
AudioOutputAudioPathMediaObject AudioOutputAudioPath
simple MediaObject use
media1 = new MediaObject;media1->addAudioPath( path1 );media1->setUrl( "file:///home/user/song.ogg" );media1->play();
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackwith more control
define the output
output = new AudioOutput;output->setCategory( Phonon::MusicCategory );path1 = new AudioPath;path1->addOutput( output );
AudioOutputAudioPathMediaObject AudioOutputAudioPath
simple MediaObject use
media1 = new MediaObject;media1->addAudioPath( path1 );media1->setUrl( "file:///home/user/song.ogg" );media1->play();
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackwith more control
define the output
output = new AudioOutput;output->setCategory( Phonon::MusicCategory );path1 = new AudioPath;path1->addOutput( output );
AudioOutputAudioPathMediaObject
AudioOutputAudioPath
simple MediaObject use
media1 = new MediaObject;media1->addAudioPath( path1 );media1->setUrl( "file:///home/user/song.ogg" );media1->play();
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackadding a Fader
recall the AudioPath
path1 = new AudioPath;
AudioOutput
AudioEffect
AudioPathMediaObject AudioOutputAudioPathMediaObject
insert the Fader
fader1 = new VolumeFaderEffect;fader1->setVolume( 1.0 );path1->insertEffect( fader1 );
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackadding a Fader
recall the AudioPath
path1 = new AudioPath;
AudioOutput
AudioEffect
AudioPathMediaObject AudioOutputAudioPathMediaObject
insert the Fader
fader1 = new VolumeFaderEffect;fader1->setVolume( 1.0 );path1->insertEffect( fader1 );
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackadding a Fader
recall the AudioPath
path1 = new AudioPath;
AudioOutput
AudioEffect
AudioPathMediaObject
AudioOutputAudioPathMediaObject
insert the Fader
fader1 = new VolumeFaderEffect;fader1->setVolume( 1.0 );path1->insertEffect( fader1 );
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackprepare next MediaObject for Crossfade
path2 = new AudioPath;path2->addOutput( output );media2 = new MediaObject;media2->addAudioPath( path2 );media2->setUrl( "file:///home/user/moremusic.
ogg" );fader2 = new VolumeFaderEffect;fader2->setVolume( 0.0 );path2->insertEffect( fader2 );
AudioOutput
AudioEffect
AudioEffect
AudioPath
AudioPath
MediaObject
MediaObject
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio Playbackprepare next MediaObject for Crossfade
path2 = new AudioPath;path2->addOutput( output );media2 = new MediaObject;media2->addAudioPath( path2 );media2->setUrl( "file:///home/user/moremusic.
ogg" );fader2 = new VolumeFaderEffect;fader2->setVolume( 0.0 );path2->insertEffect( fader2 );
AudioOutput
AudioEffect
AudioEffect
AudioPath
AudioPath
MediaObject
MediaObject
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Audio PlaybackCrossfade 2s before the first song ends
media1->setAboutToFinishTime( 2000 );connect( media1, SIGNAL( aboutToFinish( long )
), SLOT( crossfade( long ) ) );
void MyPlayer::crossfade( long remaining )
fader1->fadeOut( remaining );fader2->fadeIn( remaining );media2->play();
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Outline
What is Phonon?
Design of PhononCore ClassesCode ExamplesUser Visible FeaturesHow to Write a Backend
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
The Mixer
I Every AudioOutput has a volume controlI Volume can be read and written using IPCI Central “desktop-mixer” can then control the volume
of all Phonon applicationsI To not let the number of volume controls explode they
are be combined into the categories Notifications,Music, Movies, Games and Communication
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Devices
I central place for device selectionI select device per categoryI applications can override the selection
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Devices
I central place for device selectionI select device per categoryI applications can override the selection
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Plug Your USB Headset
I hotplugging a device will change outputs to the newdevice if it is preferred
I consider VoIPI call comes inI you answer the call using the internal soundcardI plug in the USB headsetI notification shows that the device has been switchedI you can use your headset for the conversation now
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Configurationor: Hiding tedious configuration work from the user
I applications should not need to configure the soundsystem, selecting the device to use is enough
I one central place for configurationI configuration options include
I default video output deviceI default capture devicesI whether to use a soundserver (the soundserver will
then be started by KDE and made available as adevice)
I backend specific options
I For system wide integration a shared configuration isneeded for the cases where hardware mixing orALSA dmix is unavailable
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Network and Special Routingor: How to integrate NMM
I NMM provides for a high degree of networktransparency
I Out of scope for the Phonon APII IPC hooks in the NMM backendI NMM-Phonon control application
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Outline
What is Phonon?
Design of PhononCore ClassesCode ExamplesUser Visible FeaturesHow to Write a Backend
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Where do I Start?
I many classes to implementI starting point: Backend class
I mediaframework initializationI works as factory for all other classes
I then implement MediaObject, AudioPath andAudioOutput : enough for audio playback
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Main Audio Playback Classes
MediaObject
I read and decode mediafileI play, pause, stop, seek, tickI takes multiple Audio - and VideoPath s
AudioPath
I defines routing (and signal processing)I takes multiple AudioOutput s
AudioOutput
I defines audio sinkI software volume control
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Main Audio Playback Classes
MediaObject
I read and decode mediafileI play, pause, stop, seek, tickI takes multiple Audio - and VideoPath s
AudioPath
I defines routing (and signal processing)I takes multiple AudioOutput s
AudioOutput
I defines audio sinkI software volume control
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Main Audio Playback Classes
MediaObject
I read and decode mediafileI play, pause, stop, seek, tickI takes multiple Audio - and VideoPath s
AudioPath
I defines routing (and signal processing)I takes multiple AudioOutput s
AudioOutput
I defines audio sinkI software volume control
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Optimized
I MediaObject::setUrlI start decoding the media to fill audio and video
buffersI emit the length signalI prepare for calls to hasVideo(), seekable(),
availableAudioStreams(),availableVideoStreams(),availableSubtitleStreams and totalTime()
I MediaObject::add{Audio,Video}PathI preprocess audio/video buffers with effects defined
for the pathI prepare for output to the audio device if the
AudioOutput is known
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Optimized cont.
I AbstractMediaProducer::play()I the backend should start playing immediatelyI the tick signal should be emitted - if possible without
pollingI effect change while playing
I buffers will make reaction sluggishI first priority: no dropoutsI second: no latency - overwrite as much of the buffers
with changed audio/video data as possible
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
other MediaProducers
subclasses of AbstractMediaProducerI ByteStream
I same as MediaObjectI instead of reading media data located using a URL→ media data is passed (streamed) from theapplication (or frontend)
I AvCaptureI Backend i18n(“anbieten”) audio and video capture
devicesI one video and/or one audio capture device can be
selectedI implicitly synchronized
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Two Designs
I 1:1I Phonon objects create and hold objects of the media
frameworkI good when there’s a 1:1 mapping between Phonon
classes and media framework classesI Phonon objects as description
I Phonon objects describe what the application wantsI Backend object(s) look at what the user wants and
wire media framework objects accordingly
Phonon
Matthias Kretz
What is Phonon?
Design of PhononCore Classes
Code Examples
User Visible Features
How to Write a Backend
Summary
using Multimedia functionality in KDE 4 will be easier forI developersI users
Outlook
I network interfaces, DVD-/TV-Support, OSDI backend developmentI reviewI more tests, esp. backend “certification” tests
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