Package org.jitsi.impl.neomedia.conference

Class 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 Description
      protected javax.media.protocol.CaptureDevice captureDevice
      The CaptureDevice capabilities provided by the AudioMixingPushBufferDataSources created by this AudioMixer.

    • Constructor Summary

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

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method 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.

    • 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