AuFileWriter.java 文件源码

/**
 * Returns the AudioFileFormat describing the file that will be written from this AudioInputStream.
 * Throws IllegalArgumentException if not supported.
 */
private AudioFileFormat getAudioFileFormat(Type type, AudioInputStream stream) {
    if (!isFileTypeSupported(type, stream)) {
        throw new IllegalArgumentException("File type " + type + " not supported.");
    }

    AudioFormat streamFormat = stream.getFormat();
    AudioFormat.Encoding encoding = streamFormat.getEncoding();

    if (AudioFormat.Encoding.PCM_UNSIGNED.equals(encoding)) {
        encoding = AudioFormat.Encoding.PCM_SIGNED;
    }

    // We always write big endian au files, this is by far the standard
    AudioFormat format = new AudioFormat(encoding,
                                         streamFormat.getSampleRate(),
                                         streamFormat.getSampleSizeInBits(),
                                         streamFormat.getChannels(),
                                         streamFormat.getFrameSize(),
                                         streamFormat.getFrameRate(), true);

    int fileSize;
    if (stream.getFrameLength() != AudioSystem.NOT_SPECIFIED) {
        fileSize = (int)stream.getFrameLength()*streamFormat.getFrameSize() + AuFileFormat.AU_HEADERSIZE;
    } else {
        fileSize = AudioSystem.NOT_SPECIFIED;
    }

    return new AuFileFormat(Type.AU, fileSize, format,
                            (int) stream.getFrameLength());
}