DefaultAudioMixer
@UnstableApi
class DefaultAudioMixer : AudioMixer
An AudioMixer that incrementally mixes source audio into a fixed size mixing buffer.
By default, the output signal is guaranteed to be in the range corresponding to its encoding. This range is [MIN_VALUE, MAX_VALUE] for ENCODING_PCM_16BIT, and [-1.0, 1.0] for ENCODING_PCM_FLOAT. Before adding a value to the output buffer, it is first converted to the output encoding (in the corresponding range). It is then added to the output buffer value, and the result is clipped by moving it to the closest value in this range.
Summary
Nested types |
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Public functions |
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Int |
addSource(sourceFormat: AudioProcessor.AudioFormat!, startTimeUs: Long)Adds an audio source to mix starting at the given time. |
Unit |
configure(Configures the mixer. |
ByteBuffer! |
Returns a buffer containing output audio data between its position and limit. |
Boolean |
Returns whether there is an |
Boolean |
isEnded()Returns whether the mixer can accept more |
Unit |
queueInput(sourceId: Int, sourceBuffer: ByteBuffer!)Queues audio data between the position and limit of the |
Unit |
removeSource(sourceId: Int)Removes an audio source. |
Unit |
reset()Resets the mixer to its unconfigured state, releasing any resources. |
Unit |
setEndTimeUs(endTimeUs: Long)Sets the end time of the output audio. |
Unit |
setSourceVolume(sourceId: Int, volume: Float)Sets the volume applied to future samples queued from the given source. |
Boolean |
supportsSourceAudioFormat(sourceFormat: AudioProcessor.AudioFormat!)Indicates whether the mixer supports mixing sources with the given audio format. |
Inherited functions |
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Public functions
addSource
fun addSource(sourceFormat: AudioProcessor.AudioFormat!, startTimeUs: Long): Int
Adds an audio source to mix starting at the given time.
If the mixer has already output samples past the
startTimeUs, audio from this source will be discarded up to the last output end timestamp.
If the source start time is earlier than the configured mixer start time then audio from this source will be discarded up to the mixer start time.
All audio sources start with a volume of 1.0 on all channels.
| Parameters | |
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sourceFormat: AudioProcessor.AudioFormat! |
Audio format of source buffers. |
startTimeUs: Long |
Source start time in microseconds. |
| Returns | |
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Int |
Non-negative integer identifying the source ( |
| Throws | |
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androidx.media3.common.audio.AudioProcessor.UnhandledAudioFormatException |
If the source format is not supported. |
configure
fun configure(
outputAudioFormat: AudioProcessor.AudioFormat!,
bufferSizeMs: Int,
startTimeUs: Long
): Unit
Configures the mixer.
The mixer must be configured before use and can only be reconfigured after a call to reset.
The mixing buffer size is set by bufferSizeMs and indicates how much audio can be queued before getOutput is called.
| Parameters | |
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outputAudioFormat: AudioProcessor.AudioFormat! |
The audio format of buffers returned from |
bufferSizeMs: Int |
The optional mixing buffer size in milliseconds, or |
startTimeUs: Long |
The start time of the mixer output in microseconds. |
| Throws | |
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androidx.media3.common.audio.AudioProcessor.UnhandledAudioFormatException |
If the output audio format is not supported. |
getOutput
fun getOutput(): ByteBuffer!
Returns a buffer containing output audio data between its position and limit.
The buffer will be no larger than the configured buffer size and will include no more than the frames that have been queued from all sources, up to the end time. Silence will be generated for any periods with no sources.
The buffer will always be a direct byte buffer with native byte order. Calling this method invalidates any previously returned buffer. The buffer will be empty if no output is available.
| Returns | |
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ByteBuffer! |
A buffer containing output data between its position and limit. |
hasSource
fun hasSource(sourceId: Int): Boolean
Returns whether there is an added source with the given sourceId.
isEnded
fun isEnded(): Boolean
Returns whether the mixer can accept more input or produce more output, based on the end time.
Note: If no end time is set this will always return false.
queueInput
fun queueInput(sourceId: Int, sourceBuffer: ByteBuffer!): Unit
Queues audio data between the position and limit of the sourceBuffer.
After calling this method output may be available via getOutput if all sources have queued data.
| Parameters | |
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sourceId: Int |
Source identifier from |
sourceBuffer: ByteBuffer! |
The source buffer to mix. It must be a direct byte buffer with native byte order. Its contents are treated as read-only. Its position will be advanced by the number of bytes consumed (which may be zero). The caller retains ownership of the provided buffer. |
removeSource
fun removeSource(sourceId: Int): Unit
Removes an audio source.
No more audio can be queued from this source. All audio queued before removal will be output.
setEndTimeUs
fun setEndTimeUs(endTimeUs: Long): Unit
Sets the end time of the output audio.
The mixer will not accept input nor produce output past this point.
| Parameters | |
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endTimeUs: Long |
The end time in microseconds. |
| Throws | |
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java.lang.IllegalArgumentException |
If |
setSourceVolume
fun setSourceVolume(sourceId: Int, volume: Float): Unit
Sets the volume applied to future samples queued from the given source.
supportsSourceAudioFormat
fun supportsSourceAudioFormat(sourceFormat: AudioProcessor.AudioFormat!): Boolean
Indicates whether the mixer supports mixing sources with the given audio format.