Android APIs
public static class

AudioFormat.Builder

extends Object
java.lang.Object
   ↳ android.media.AudioFormat.Builder

Class Overview

Builder class for AudioFormat objects. Use this class to configure and create an AudioFormat instance. By setting format characteristics such as audio encoding, channel mask or sample rate, you indicate which of those are to vary from the default behavior on this device wherever this audio format is used. See AudioFormat for a complete description of the different parameters that can be used to configure an AudioFormat instance.

AudioFormat is for instance used in AudioTrack(AudioAttributes, AudioFormat, int, int, int). In this constructor, every format characteristic set on the Builder (e.g. with setSampleRate(int)) will alter the default values used by an AudioTrack. In this case for audio playback with AudioTrack, the sample rate set in the Builder would override the platform output sample rate which would otherwise be selected by default.

Summary

Public Constructors
AudioFormat.Builder()
Constructs a new Builder with none of the format characteristics set.
AudioFormat.Builder(AudioFormat af)
Constructs a new Builder from a given AudioFormat.
Public Methods
AudioFormat build()
Combines all of the format characteristics that have been set and return a new AudioFormat object.
AudioFormat.Builder setChannelIndexMask(int channelIndexMask)
Sets the channel index mask.
AudioFormat.Builder setChannelMask(int channelMask)
Sets the channel position mask.
AudioFormat.Builder setEncoding(int encoding)
Sets the data encoding format.
AudioFormat.Builder setSampleRate(int sampleRate)
Sets the sample rate.
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public AudioFormat.Builder ()

Added in API level 21

Constructs a new Builder with none of the format characteristics set.

public AudioFormat.Builder (AudioFormat af)

Added in API level 21

Constructs a new Builder from a given AudioFormat.

Parameters
af the AudioFormat object whose data will be reused in the new Builder.

Public Methods

public AudioFormat build ()

Added in API level 21

Combines all of the format characteristics that have been set and return a new AudioFormat object.

Returns

public AudioFormat.Builder setChannelIndexMask (int channelIndexMask)

Added in API level 23

Sets the channel index mask. A channel index mask specifies the association of audio samples in the frame with numbered endpoint channels. The i-th bit in the channel index mask corresponds to the i-th endpoint channel. For example, an endpoint with four channels is represented as index mask bits 0 through 3. This setChannelMask(int) for a positional mask interpretation.

Both AudioTrack and AudioRecord support a channel index mask. If a channel index mask is specified it is used, otherwise the channel position mask specified by setChannelMask is used. For AudioTrack and AudioRecord, a channel position mask is not required if a channel index mask is specified.

Parameters
channelIndexMask describes the configuration of the audio channels.

For output, the channelIndexMask is an OR-ed combination of bits representing the mapping of AudioTrack write samples to output sink channels. For example, a mask of 0xa, or binary 1010, means the AudioTrack write frame consists of two samples, which are routed to the second and the fourth channels of the output sink. Unmatched output sink channels are zero filled and unmatched AudioTrack write samples are dropped.

For input, the channelIndexMask is an OR-ed combination of bits representing the mapping of input source channels to AudioRecord read samples. For example, a mask of 0x5, or binary 101, will read from the first and third channel of the input source device and store them in the first and second sample of the AudioRecord read frame. Unmatched input source channels are dropped and unmatched AudioRecord read samples are zero filled.

Returns
  • the same Builder instance.
Throws
IllegalArgumentException if the channel index mask is invalid or if both channel index mask and channel position mask are specified but do not have the same channel count.

public AudioFormat.Builder setEncoding (int encoding)

Added in API level 21

Sets the data encoding format.

Returns
  • the same Builder instance.

public AudioFormat.Builder setSampleRate (int sampleRate)

Added in API level 21

Sets the sample rate.

Parameters
sampleRate the sample rate expressed in Hz
Returns
  • the same Builder instance.