How do I save the microphone audio as a proper WAF file?

By Wayan in Sound API 0 Comment

To save the microphone audio as a proper WAV file, you need to use the AudioSystem.write() method. WAV files contain raw PCM data combined with a header that describes important details, such as the sample rate, number of channels, etc. Java’s javax.sound.sampled package makes it easy to save the audio in this format.

Example: Saving Captured Audio as a WAV File

Here’s how you can save audio directly as a WAV file while using TargetDataLine:

package org.kodejava.sound;

import javax.sound.sampled.*;
import java.io.File;
import java.io.IOException;

public class MicrophoneToWav {

    public static void main(String[] args) {
        new MicrophoneToWav().start();
    }

    public void start() {
        // Define the audio format
        AudioFormat audioFormat = new AudioFormat(
                AudioFormat.Encoding.PCM_SIGNED, // Encoding
                44100.0f, // Sample rate (44.1kHz)
                16,       // Sample size in bits
                2,        // Channels (stereo)
                4,        // Frame size (16 bits/sample * 2 channels)
                44100.0f, // Frame rate (matches sample rate for PCM)
                false     // Big-endian (false = little-endian)
        );

        // Get and configure the TargetDataLine
        TargetDataLine microphone;
        try {
            microphone = AudioSystem.getTargetDataLine(audioFormat);
            microphone.open(audioFormat);

            File wavFile = new File("D:/Sound/output.wav");

            // Start capturing audio
            microphone.start();
            System.out.println("Recording started... Press Ctrl+C or stop to terminate.");

            // Set up a shutdown hook for graceful termination
            Runtime.getRuntime().addShutdownHook(new Thread(() -> stop(microphone)));

            // Save the microphone data to a WAV file
            writeAudioToWavFile(microphone, wavFile);

        } catch (LineUnavailableException e) {
            e.printStackTrace();
        }
    }

    private void writeAudioToWavFile(TargetDataLine microphone, File wavFile) {
        try (AudioInputStream audioInputStream = new AudioInputStream(microphone)) {
            // Write the stream to a WAV file
            AudioSystem.write(audioInputStream, AudioFileFormat.Type.WAVE, wavFile);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            stop(microphone);
        }
    }

    public void stop(TargetDataLine microphone) {
        if (microphone != null && microphone.isOpen()) {
            microphone.flush();
            microphone.stop();
            microphone.close();
            System.out.println("Microphone stopped.");
        }
    }
}

Explanation

  1. Audio Format:
    • The AudioFormat specifies PCM encoding with a sample rate of 44100 Hz, 16-bit samples, 2 channels (stereo), and little-endian format.
  2. TargetDataLine:
    • A TargetDataLine is used to read audio data from the microphone.
  3. AudioInputStream:
    • The AudioInputStream wraps the TargetDataLine, creating a stream of audio data in chunks.
  4. AudioSystem.write():
    • The AudioSystem.write() method writes the audio stream directly to a .wav file using AudioFileFormat.Type.WAVE.
    • WAV files are chunks of PCM raw data with a proper header. This method handles creating the header for you.
  5. Shutdown Hook:
    • A shutdown hook ensures that resources (like the microphone) are released when the application stops or when the user presses Ctrl+C.
  6. Graceful Stop:
    • The stop() method safely terminates the recording loop and releases resources, such as the TargetDataLine.

Introduction to Java Sound API

By Wayan in Sound API 0 Comment

The Java Sound API is a feature of the Java platform, designed to provide low-level support for audio operations such as audio playback and capture (recording), audio format conversions, and sequencing and synthesizing of MIDI (Musical Instrument Digital Interface)

Overview

Java Sound API, included in the Java SE (Standard Edition), is a powerful and flexible toolkit for creating interactive audio applications. It is designed in a way that it can be easily scalable, extended, or integrated with other application-specific solutions.

Developers can take advantage of a set of classes and interfaces that allows them to incorporate both simple and complex sound functionality into their Java programs. Provisions are also available for sophisticated control over audio mixing, audio data format conversions, and real-time streaming.

Capabilities

The Java Sound API comes with a robust set of features:

  1. Audio Playback and Recording: You can play sound data from an application, from a resource embedded within an application jar file, or from a location on the internet. You can also record sound data from different sources and store it in a variety of audio file formats.
  2. Audio Mixing: The Sound API allows you to control the audio (volume, balance, etc.) on a per-channel basis, mix multiple audio streams, and manipulate the audio data before it’s sent to an actual audio device.
  3. MIDI Sequencing and Synthesizing: Java Sound API supports MIDI, a technology widely used for music synthesis in the multimedia industry. MIDI events can be sequenced (i.e., organised in a specific order) and synthesized (i.e., embedded within the application) using the Java Sound API.

Working with Java Sound API

Understanding how data is moved and processed is crucial when working with the Java Sound API. It is designed in such a way that obtained media data from one source (like a file or a microphone). Manipulates it in some manner and then sends it to a destination (like an audio output device or a file).

Sounds start as an AudioInputStream. The Java Sound API uses an AudioSystem to provide many of the operations you may need to perform on that stream, such as obtaining a stream from an audio file.

Here is a basic example of how you can use the Java Sound API to play audio:

package org.kodejava.sound;

import javax.sound.sampled.*;

import java.net.URL;
import java.util.Objects;

public class SoundTest {
    public static void main(String[] args) {
        try {
            URL url = SoundTest.class.getResource("/sound.wav");
            AudioInputStream audioStream = AudioSystem.getAudioInputStream(Objects.requireNonNull(url));

            AudioFormat format = audioStream.getFormat();
            DataLine.Info info = new DataLine.Info(Clip.class, format);

            Clip audioClip = (Clip) AudioSystem.getLine(info);
            audioClip.open(audioStream);
            audioClip.start();

            // Keep the application running for the duration of the audio clip
            Thread.sleep(audioClip.getMicrosecondLength() / 1000);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

The above example loads an audio file, gets the required information from the file, opens the clip, and starts playing it.

To read a WAV file stored in the resources directory of a Maven project, you would use the getResource method. This method is part of the standard Java Class Library and can locate any resources that are on the Java ClassPath.

In this example, we assume that sound.wav is located directly under src/main/resources. If the file is in a subdirectory, you would adjust the argument to getResource accordingly. For example, if sound.wav is in src/main/resources/audio, you would use /audio/sound.wav.

Conclusion

The Java Sound API offers powerful lower-level control over audio operations, creating more room for customization and integrations. Whether you’re looking to add simple sound effects or build an audio-rich program, the Java Sound API is a robust, intuitive, and flexible choice.