java-racs

java-racs is the java client library for RACS.

Installation

To install java-racs, add the following dependency to your pom.xml:

<dependency>
    <groupId>com.racslabs</groupId>
    <artifactId>racs</artifactId>
    <version>0.1.0</version>
</dependency>

Basic Operations

To open a connection, simply create a new Racs instance and provide the host and port.

import com.racslabs.Racs;

Racs racs = new Racs("localhost", 6381);

Streaming Audio

The pipeline function is used to chain together multiple RACS commands and execute them sequentially. In the below example, a new audio stream is created and opened. Then PCM data is chunked into frames and streamed to the RACS server.

import com.racslabs.Racs;
import com.racslabs.command.Pipeline;

// Connect to the RACS server
Racs racs = new Racs("localhost", 6381);

// Get pipeline
Pipeline pipeline = racs.pipeline();

// Create a new audio stream using pipeline
pipeline.create("vocals", 44100, 2, 16).execute(); // stream-id, sample-rate, channels, bit-depth

// Reset pipeline
pipeline.reset();

// Prepare array of PCM samples (interleaved L/R, 16- or 24-bit integers)
int[] data = /* your PCM audio data */

// Stream PCM data to the server
racs.stream("vocals")
        .chunkSize(1024 * 32)
        .batchSize(50)
        .compression(true)
        .compressionLevel(8)
        .execute(data);

If chunkSize, batchSize, compression and compressionLevel are not provided, the default values will be used.

// Stream PCM data to the server
racs.stream("vocals").execute(data);

Stream ids stored in RACS can be queried using the list command. list takes a glob pattern and returns a List<String> object of streams ids matching the pattern.

import com.racslabs.Racs;
import com.racslabs.command.Pipeline;

// Connect to the RACS server
Racs racs = new Racs("localhost", 6381);

// Get pipeline
Pipeline pipeline = racs.pipeline();

// Run list command matching "*" pattern
List<String> result = (List<String>)pipeline.list("*").execute();

Extracting Audio

The below example extracts a 30-second PCM audio segment using the range command. It then encodes the data to MP3 and writes the resulting bytes to a file.

import com.racslabs.Racs;
import com.racslabs.command.Pipeline;

import java.io.FileOutputStream;
import java.io.IOException;

// Connect to the RACS server
Racs racs = new Racs("localhost", 6381);

// Get pipeline
Pipeline pipeline = racs.pipeline();

// Extract PCM data
// Encode the audio to MP3
byte[] result = (byte[]) pipeline.range("vocals", 0.0, 30.0) // stream-id, start (seconds), duration (seconds)
        .encode("audio/wav")
        .execute();

// Write to a file
try (FileOutputStream fos = new FileOutputStream("vocals.wav")) {
    fos.write(result);
} catch (IOException e) {
    e.printStackTrace();
}

Metadata

Stream metadata can be retrieved using the meta command. meta takes the stream id and metadata attribute as parameters.

import com.racslabs.Racs;
import com.racslabs.command.Pipeline;

// Connect to the RACS server
Racs racs = new Racs("localhost", 6381);

// Get pipeline
Pipeline pipeline = racs.pipeline();

// Get sample rate attribute for stream
long result = (long) pipeline.meta("vocals", "sample_rate").execute();

The supported metadata attributes are:

Attribute	Description
channels	Channel count of the audio stream.
sample_rate	Sample rate of the audio stream (Hz).
bit_depth	Bit depth of the audio stream.
ref	Reference timestamp (milliseconds UTC).
size	Size of the uncompressed audio stream in bytes.

Raw Command Execution

To execute raw command strings, use the executeCommand function.

import com.racslabs.Racs;

Racs racs = new Racs("localhost", 6381);

long result = (long) racs.executeCommand("EVAL '(+ 1 2 3)'");

Refer to the documentation in RACS for the commands.