Java-based audio processing methods and practices

With the continuous development of the digital age, sound has become an indispensable part of people's daily lives. In the audio field, audio processing technology is also constantly developing and improving. In this process, the Java language, as a powerful programming language, also has many applications in audio processing. This article will introduce Java-based audio processing methods and practices.

Audio processing technology can be divided into three categories, namely audio collection, audio processing and audio playback. In Java, you can use Java Sound API and Java Media Framework to complete these functions, and you can also use third-party libraries to enhance these functions, such as JAVE (Java Audio Video Encoder).

1. Audio collection

Audio collection is the first step in audio processing and is mainly used to obtain external audio signals. In Java, you can use the TargetDataLine class in the Java Sound API to implement audio collection. First, you need to obtain the instance object of TargetDataLine, which needs to specify the format of the audio data to be collected. The format can be defined through the AudioFormat class, which includes information such as sampling rate, number of channels, and number of bits per sample value.

Next, you can use the start() method to start TargetDataLine, and then call the read() method to read the audio data. The read() method reads the specified amount of audio data from the input buffer and stores it into a byte array.

.

// 定义音频格式
AudioFormat format = new AudioFormat(44100, 16, 2, true, true);

// 获取TargetDataLine实例对象
DataLine.Info info = new DataLine.Info(TargetDataLine.class, format);
TargetDataLine line = (TargetDataLine) AudioSystem.getLine(info);

// 开始采集音频数据
line.open(format);
line.start();
byte[] buffer = new byte[1024];
int count = line.read(buffer, 0, buffer.length);

2. Audio processing

Audio processing is a series of processing performed on the audio signal after acquiring it, including noise reduction, reverberation, equalizer, etc. . In Java, audio data can be processed through custom classes or with the help of third-party libraries.

1. Custom classes process audio data

The basic method for custom classes to process audio data is to convert the read audio data into numerical values, and then compare these numerical values Process it and finally convert the processed result back into audio data.

Example: Double processing of audio data

// 对采样值进行加倍处理
for (int i = 0; i < buffer.length; i = i + 2) {
    byte b1 = buffer[i];
    byte b2 = buffer[i + 1];

    short s = (short) ((b2 << 8) | b1);
    s *= 2;

    buffer[i] = (byte) s;
    buffer[i + 1] = (byte) (s >> 8);
}

2. Third-party library

a. JAVE (Java Audio Video Encoder)

JAVE is a Java audio and video codec that provides many methods for processing audio and video files. It encapsulates FFMpeg, Mencoder and other video codecs, providing Java developers with a simpler and easier way to use.

Its common operations include audio transcoding, audio editing, audio merging, audio extraction, etc. It is simple and convenient to use.

b. Dritan Alsela's Java DSP Collection

This is an open source Java signal processing library. It is designed for those who want to implement audio processing, but do not have time to deal with C, C code provides a solution for Java programmers. It includes functions such as FFT conversion, DFT conversion, and filters. Using this library requires a certain foundation in mathematics and signal processing.

3. Audio playback

Audio playback is the process of outputting processed audio data to external devices. In Java, you can use the SourceDataLine class in the Java Sound API to implement audio playback. First, you need to obtain an instance object of SourceDataLine, which needs to specify the format of the audio data to be output. Format can also be defined through the AudioFormat class.

Next, you can use the start() method to start SourceDataLine, and then call the write() method to write the processed audio data into the output buffer.

.

// 定义音频格式
AudioFormat format = new AudioFormat(44100, 16, 2, true, true);

// 获取SourceDataLine实例对象
DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);
SourceDataLine line = (SourceDataLine) AudioSystem.getLine(info);

// 输出音频数据
line.open(format);
line.start();
line.write(buffer, 0, count);

Summary

The above is an introduction to Java-based audio processing methods and practices. Through the Java Sound API and third-party libraries, we can easily complete functions such as audio collection, audio processing, and audio playback. In the future, as Java developers' demands for audio processing continue to increase, I believe that more efficient and easy-to-use audio processing libraries and tools will emerge.

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