jt-adpcm provides a high-quality ADPCM encoder and an ADPCM decoder for Java 9+. It is a port of David Bryant's ADPCM-XQ library.
Add the following to the <dependencies> element in your pom.xml:
<dependency>
<groupId>com.github.mdzhb</groupId>
<artifactId>jt-adpcm</artifactId>
<version>1.1.0</version>
</dependency>To encode 16-bit PCM data, place it into a java.nio.ShortBuffer, create an ADPCMEncoderConfig, then use the configuration to instantiate an ADPCMEncoder. The ADPCMEncoderConfig's computeOuputSize(ShortBuffer) method will return the minimum size of the output buffer for the given input.
ByteBuffer encodePCM(ShortBuffer pcmInput, int channels, int sampleRate, boolean shape) {
ADPCMEncoderConfig cfg =
ADPCMEncoder.configure()
.setChannels (channels) // 1 for mono, 2 for stereo
.setSampleRate (sampleRate) // sample rate in Hz
.setNoiseShaping(shape) // noise shaping; true=on, false=off
.setBlockSize (ADPCMDecoderConfig.AUTO_BLOCK_SIZE) // compute block size automatically
.end(); // create the configuration object
// ADPCMEncoderConfig.computeOutputSize(ShortBuffer) computes the minimum output buffer size
ByteBuffer adpcmOutput = ByteBuffer.allocate(cfg.computeOutputSize(pcmInput));
// this returns the adpcmOutput buffer
return new ADPCMEncoder(cfg).encode(pcmInput, adpcmOutput).rewind();
}To decode ADPCM data to 16-bit PCM, place the ADPCM data into a java.nio.ByteBuffer, create an ADPCMDecoderConfig, then use the configuration to instantiate an ADPCMDecoder. The decoder computes the number of samples it must decode with samples = inputBuffer.remaining() / decoderConfig.getChannels().
ShortBuffer decodeADPCM(ByteBuffer adpcmInput, int channels, int samples, int sampleRate) {
ADPCMDecoderConfig cfg =
ADPCMDecoder.configure()
.setChannels (channels) // 1 for mono, 2 for stereo
.setSampleRate(sampleRate) // sample rate in Hz
.setBlockSize (ADPCMDecoderConfig.AUTO_BLOCK_SIZE) // compute block size with the formula used by the encoder
.end(); // create the configuration object
// if `samples` is the length of the sound in samples, we need to double the length of the buffer for stereo data
ShortBuffer pcmOutput = ShortBuffer.allocate(channels * samples);
// this returns the pcmOutput buffer
return new ADPCMDecoder(cfg).decode(adpcmInput, pcmOutput).rewind();
}To read and write WAV files, use the com.jiggawatt.jt.tools.adpcm.util.WAVFile class. The following example reads a PCM file using an InputStream, encodes it, and dumps the resulting ADPCM audio to another file. It uses the information stored in the input WAV header to configure the encoder.
void encode(boolean shape, InputStream in, OutputStream out) throws IOException {
// use one of the `WAVFile` factory methods to obtain an instance
WAVFile wavInput = WAVFile.fromStream(in);
// `WAVFile.getReadOnlyData()` provides you with a read-only view of the audio data stored in the file
ShortBuffer pcmInput = wavInput.getReadOnlyData().asShortBuffer();
// the input `WAVFile` gives us some of the information we need to configure the encoder
ADPCMEncoderConfig cfg =
ADPCMEncoder.configure()
.setChannels (wavInput.getChannels())
.setSampleRate (wavInput.getSampleRate())
.setNoiseShaping(shape)
.setBlockSize (ADPCMDecoderConfig.AUTO_BLOCK_SIZE)
.end();
ByteBuffer adpcmOutput = ByteBuffer.allocate(cfg.computeOutputSize(pcmInput));
// this convenience method generates WAV header info from your encoder configuration
WAVFile wavOutput = WAVFile.fromADPCMBuffer(adpcmOutput, wavInput.getNumSamples(), cfg);
// finally, WAVFile.dump() writes the file to the given stream
wavOutput.dump(out);
}Dumping a decoded file works similarly.
void decode(InputStream in, OutputStream out) throws IOException {
WAVFile wavInput = WAVFile.fromStream(in);
ByteBuffer adpcmInput = wavInput.getReadOnlyData();
// the input `WAVFile` gives us the information we need to configure the decoder
ADPCMDecoderConfig cfg =
ADPCMDecoder.configure()
.setChannels (wavInput.getChannels())
.setSampleRate(wavInput.getSampleRate())
.setBlockSize (wavInput.getBlockSize())
.end();
ByteBuffer pcmOutput = ByteBuffer.allocate(wavInput.getNumSamples() * wavInput.getChannels() * 2);
new ADPCMDecoder(cfg).decode(adpcmInput, pcmOutput.asShortBuffer());
// create a pcm wav file from the decoder's output
WAVFile wavOutput = WAVFile.fromPCMBuffer(pcmOutput, wavInput.getChannels(), wavInput.getSampleRate());
// finally, WAVFile.dump() writes the file to the given stream
wavOutput.dump(out);
}