OpusUtil

Kotlin |Java

@UnstableApi
public class OpusUtil

Utility methods for handling Opus audio streams.

Summary

Constants
`static final int`	`MAX_BYTES_PER_SECOND = 63750` Maximum achievable Opus bitrate.
`static final int`	`SAMPLE_RATE = 48000` Opus streams are always 48000 Hz.

Public methods
`static List<byte[]>`	`buildInitializationData(byte[] header)` Builds codec initialization data from an Opus Identification Header.
`static int`	`getChannelCount(byte[] header)` Parses the channel count from an Opus Identification Header.
`static long`	`getPacketDurationUs(byte[] buffer)` Returns the duration of the given audio packet.
`static int`	`getPreSkipSamples(byte[] header)` Returns the number of pre-skip samples specified by the given Opus codec initialization data.
`static boolean`	`needToDecodeOpusFrame(long startTimeUs, long frameTimeUs)` Returns whether an Opus frame should be sent to the decoder as it is either past the start position or within the seek-preroll duration.
`static int`	`parseOggPacketAudioSampleCount(ByteBuffer buffer)` Returns the number of audio samples in the given Ogg encapuslated Opus packet.
`static int`	`parseOggPacketForPreAudioSampleByteCount(ByteBuffer buffer)` Calculate the offset from the start of the buffer to audio sample Ogg packets.
`static int`	`parsePacketAudioSampleCount(ByteBuffer buffer)` Returns the number of audio samples in the given audio packet.

public static final int MAX_BYTES_PER_SECOND = 63750

Maximum achievable Opus bitrate.

public static final int SAMPLE_RATE = 48000

Opus streams are always 48000 Hz.

public static List<byte[]> buildInitializationData(byte[] header)

Builds codec initialization data from an Opus Identification Header.

Parameters
`byte[] header`	An Opus Identification Header, as defined by RFC 7845.

Returns
`List<byte[]>`	Codec initialization data suitable for an Opus MediaCodec.

public static int getChannelCount(byte[] header)

Parses the channel count from an Opus Identification Header.

Parameters
`byte[] header`	An Opus Identification Header, as defined by RFC 7845.

Returns
`int`	The parsed channel count.

public static long getPacketDurationUs(byte[] buffer)

Returns the duration of the given audio packet.

Parameters
`byte[] buffer`	The audio packet.

Returns
`long`	Returns the duration of the given audio packet, in microseconds.

public static int getPreSkipSamples(byte[] header)

Returns the number of pre-skip samples specified by the given Opus codec initialization data.

Parameters
`byte[] header`	The Opus Identification header.

Returns
`int`	The number of pre-skip samples.

public static boolean needToDecodeOpusFrame(long startTimeUs, long frameTimeUs)

Returns whether an Opus frame should be sent to the decoder as it is either past the start position or within the seek-preroll duration.

The measure of whether an Opus frame should not be decoded is if its time precedes the start position by more than the default seek-preroll value.

Parameters
`long startTimeUs`	The time to start playing at.
`long frameTimeUs`	The time of the Opus sample.

Returns
`boolean`	Whether the frame should be decoded.

public static int parseOggPacketAudioSampleCount(ByteBuffer buffer)

Returns the number of audio samples in the given Ogg encapuslated Opus packet.

The buffer's position is not modified.

Parameters
`ByteBuffer buffer`	The audio packet.

Returns
`int`	Returns the number of audio samples in the packet.

public static int parseOggPacketForPreAudioSampleByteCount(ByteBuffer buffer)

Calculate the offset from the start of the buffer to audio sample Ogg packets.

Parameters
`ByteBuffer buffer`	containing the Ogg Encapsulated Opus audio bitstream.

Returns
`int`	the offset before the Ogg packet containing audio samples.

public static int parsePacketAudioSampleCount(ByteBuffer buffer)

Returns the number of audio samples in the given audio packet.

The buffer's position is not modified.

Parameters
`ByteBuffer buffer`	The audio packet.

Returns
`int`	Returns the number of audio samples in the packet.