org.jitsi.impl.neomedia.conference

Class AudioMixer

java.lang.Object

org.jitsi.impl.neomedia.conference.AudioMixer

public class AudioMixer
extends Object

Represents an audio mixer which manages the mixing of multiple audio streams i.e. it is able to output a single audio stream which contains the audio of multiple input audio streams.

The input audio streams are provided to the AudioMixer through addInDataSource(DataSource) in the form of input DataSources giving access to one or more input SourceStreams.

The output audio stream representing the mix of the multiple input audio streams is provided by the AudioMixer in the form of a AudioMixingPushBufferDataSource giving access to a AudioMixingPushBufferStream. Such an output is obtained through createOutDataSource(). The AudioMixer is able to provide multiple output audio streams at one and the same time, though, each of them containing the mix of a subset of the input audio streams.

Author:

Lyubomir Marinov

Field Summary

Fields

Modifier and Type	Field and Description
protected javax.media.protocol.CaptureDevice	captureDevice The CaptureDevice capabilities provided by the AudioMixingPushBufferDataSources created by this AudioMixer.

Constructor Summary

Constructors

Constructor and Description
AudioMixer(javax.media.protocol.CaptureDevice captureDevice) Initializes a new AudioMixer instance.

Method Summary

Modifier and Type	Method and Description
void	addInDataSource(javax.media.protocol.DataSource inDataSource) Adds a new input DataSource to the collection of input DataSources from which this instance reads audio.
protected void	connect(javax.media.protocol.DataSource dataSource, javax.media.protocol.DataSource inDataSource) Connects to a specific DataSource which this AudioMixer will read audio from.
AudioMixingPushBufferDataSource	createOutDataSource() Creates a new AudioMixingPushBufferDataSource which gives access to a single audio stream representing the mix of the audio streams input into this AudioMixer through its input DataSources.
AudioMixingPushBufferDataSource	getLocalOutDataSource() Gets the AudioMixingPushBufferDataSource containing the mix of all input DataSources excluding the CaptureDevice of this AudioMixer and is thus meant for playback on the local peer in a call.
TranscodingDataSource	getTranscodingDataSource(javax.media.protocol.DataSource inDataSource) Searches this object's inDataSources for one that matches inDataSource, and returns it's associated TranscodingDataSource.
protected void	read(javax.media.protocol.PushBufferStream stream, javax.media.Buffer buffer, javax.media.protocol.DataSource dataSource) Reads media from a specific PushBufferStream which belongs to a specific DataSource into a specific output Buffer.
void	removeInDataSources(DataSourceFilter dataSourceFilter) Removes DataSources accepted by a specific DataSourceFilter from the list of input DataSources of this AudioMixer from which it reads audio to be mixed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

captureDevice

protected final javax.media.protocol.CaptureDevice captureDevice

The CaptureDevice capabilities provided by the AudioMixingPushBufferDataSources created by this AudioMixer. JMF's Manager.createMergingDataSource(DataSource[]) requires the interface implementation for audio if it is implemented for video and it is indeed the case for our use case of AudioMixingPushBufferDataSource.

Constructor Detail

AudioMixer

public AudioMixer(javax.media.protocol.CaptureDevice captureDevice)

Initializes a new AudioMixer instance. Because JMF's Manager.createMergingDataSource(DataSource[]) requires the implementation of CaptureDevice for audio if it is implemented for video and it is indeed the cause for our use case of AudioMixingPushBufferDataSource, the new AudioMixer instance provides specified CaptureDevice capabilities to the AudioMixingPushBufferDataSources it creates. The specified CaptureDevice is also added as the first input DataSource of the new instance.

Parameters:

captureDevice - the CaptureDevice capabilities to be provided to the AudioMixingPushBufferDataSources created by the new instance and its first input DataSource

Method Detail

addInDataSource

public void addInDataSource(javax.media.protocol.DataSource inDataSource)

Adds a new input DataSource to the collection of input DataSources from which this instance reads audio. If the specified DataSource indeed provides audio, the respective contributions to the mix are always included.

Parameters:

inDataSource - a new DataSource to input audio to this instance

connect

protected void connect(javax.media.protocol.DataSource dataSource,
                       javax.media.protocol.DataSource inDataSource)
                throws IOException

Connects to a specific DataSource which this AudioMixer will read audio from. The specified DataSource is known to exist because of a specific DataSource added as an input to this instance i.e. it may be an actual input DataSource added to this instance or a DataSource transcoding an input DataSource added to this instance.

Parameters:

dataSource - the DataSource to connect to

inDataSource - the DataSource which is the cause for dataSource to exist in this AudioMixer

Throws:

IOException - if anything wrong happens while connecting to dataSource

createOutDataSource

public AudioMixingPushBufferDataSource createOutDataSource()

Creates a new AudioMixingPushBufferDataSource which gives access to a single audio stream representing the mix of the audio streams input into this AudioMixer through its input DataSources. The returned AudioMixingPushBufferDataSource can also be used to include new input DataSources in this AudioMixer but have their contributions not included in the mix available through the returned AudioMixingPushBufferDataSource.

Returns:

a new AudioMixingPushBufferDataSource which gives access to a single audio stream representing the mix of the audio streams input into this AudioMixer through its input DataSources

getLocalOutDataSource

public AudioMixingPushBufferDataSource getLocalOutDataSource()

Gets the AudioMixingPushBufferDataSource containing the mix of all input DataSources excluding the CaptureDevice of this AudioMixer and is thus meant for playback on the local peer in a call.

Returns:

the AudioMixingPushBufferDataSource containing the mix of all input DataSources excluding the CaptureDevice of this AudioMixer and is thus meant for playback on the local peer in a call

getTranscodingDataSource

public TranscodingDataSource getTranscodingDataSource(javax.media.protocol.DataSource inDataSource)

Searches this object's inDataSources for one that matches inDataSource, and returns it's associated TranscodingDataSource. Currently this is only used when the MediaStream needs access to the codec chain used to playback one of it's ReceiveStreams.

Parameters:

inDataSource - the DataSource to search for.

Returns:

The TranscodingDataSource associated with inDataSource, if we can find one, null otherwise.

read

protected void read(javax.media.protocol.PushBufferStream stream,
                    javax.media.Buffer buffer,
                    javax.media.protocol.DataSource dataSource)
             throws IOException

Reads media from a specific PushBufferStream which belongs to a specific DataSource into a specific output Buffer. Allows extenders to tap into the reading and monitor and customize it.

Parameters:

stream - the PushBufferStream to read media from and known to belong to the specified DataSOurce

buffer - the output Buffer in which the media read from the specified stream is to be written so that it gets returned to the caller

dataSource - the DataSource from which stream originated

Throws:

IOException - if anything wrong happens while reading from the specified stream

removeInDataSources

public void removeInDataSources(DataSourceFilter dataSourceFilter)

Removes DataSources accepted by a specific DataSourceFilter from the list of input DataSources of this AudioMixer from which it reads audio to be mixed.

Parameters:

dataSourceFilter - the DataSourceFilter which selects the DataSources to be removed from the list of input DataSources of this AudioMixer from which it reads audio to be mixed