DefaultAudioMixer
@UnstableApi
public final class DefaultAudioMixer implements 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 final class DefaultAudioMixer.Factory implements AudioMixer.FactoryAn |
Public methods |
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int |
addSource(AudioProcessor.AudioFormat sourceFormat, long startTimeUs)Adds an audio source to mix starting at the given time. |
void |
configure(Configures the mixer. |
ByteBuffer |
Returns a buffer containing output audio data between its position and limit. |
boolean |
hasSource(int sourceId)Returns whether there is an |
boolean |
isEnded()Returns whether the mixer can accept more |
void |
queueInput(int sourceId, ByteBuffer sourceBuffer)Queues audio data between the position and limit of the |
void |
removeSource(int sourceId)Removes an audio source. |
void |
reset()Resets the mixer to its unconfigured state, releasing any resources. |
void |
setEndTimeUs(long endTimeUs)Sets the end time of the output audio. |
void |
setSourceVolume(int sourceId, float volume)Sets the volume applied to future samples queued from the given source. |
boolean |
supportsSourceAudioFormat(AudioProcessor.AudioFormat sourceFormat)Indicates whether the mixer supports mixing sources with the given audio format. |
Inherited methods |
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Public methods
addSource
public int addSource(AudioProcessor.AudioFormat sourceFormat, long startTimeUs)
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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AudioProcessor.AudioFormat sourceFormat |
Audio format of source buffers. |
long startTimeUs |
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
public void configure(
AudioProcessor.AudioFormat outputAudioFormat,
int bufferSizeMs,
long startTimeUs
)
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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AudioProcessor.AudioFormat outputAudioFormat |
The audio format of buffers returned from |
int bufferSizeMs |
The optional mixing buffer size in milliseconds, or |
long startTimeUs |
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
public ByteBuffer getOutput()
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
public boolean hasSource(int sourceId)
Returns whether there is an added source with the given sourceId.
isEnded
public boolean isEnded()
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
public void queueInput(int sourceId, ByteBuffer sourceBuffer)
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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int sourceId |
Source identifier from |
ByteBuffer sourceBuffer |
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
public void removeSource(int sourceId)
Removes an audio source.
No more audio can be queued from this source. All audio queued before removal will be output.
| Parameters | |
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int sourceId |
Source identifier from |
setEndTimeUs
public void setEndTimeUs(long endTimeUs)
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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long endTimeUs |
The end time in microseconds. |
| Throws | |
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java.lang.IllegalArgumentException |
If |
setSourceVolume
public void setSourceVolume(int sourceId, float volume)
Sets the volume applied to future samples queued from the given source.
| Parameters | |
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int sourceId |
Source identifier from |
float volume |
Non-negative scalar applied to all source channels. |
supportsSourceAudioFormat
public boolean supportsSourceAudioFormat(AudioProcessor.AudioFormat sourceFormat)
Indicates whether the mixer supports mixing sources with the given audio format.