Question

解码10秒需要1分钟，如何更快地解码MP3？

public static byte[] decode(String path, int startMs, int maxMs) throws FileNotFoundException 
{
    float totalMs = 0;
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    File file = new File(path);
    InputStream inputStream = new BufferedInputStream(new FileInputStream(file), 8 * 1024);
    try {
        Bitstream bitstream = new Bitstream(inputStream);
        Decoder decoder = new Decoder();
        boolean done = false;
        while (! done) {
            Header frameHeader = bitstream.readFrame();
            totalMs += frameHeader.ms_per_frame();
            SampleBuffer output = (SampleBuffer) decoder.decodeFrame(frameHeader, bitstream);  
            short[] pcm = output.getBuffer();   

            for (short s : pcm) {
                os.write(s & 0xff);
                os.write((s >> 8 ) & 0xff);
              }
            if (totalMs >= (startMs + maxMs)) {
                done = true;
            }
            bitstream.closeFrame();
        } 
        return os.toByteArray();
    }catch(Exception e){
          e.printStackTrace();
    }
    return null;    
}

Answer 1

您上面列出的decode方法只是示例代码。你不应该在生产中使用它，也就是说，你正在传递路径并重复重复打开同一个文件，这是一项代价高昂的操作。

相反，您应该将此方法之外的文件打开到InputStream中，然后将InputStream传递给方法。请参阅此问题以获取示例：Android JellyBean network media issue

使用jlayer在Android上慢速解码MP3

1 个答案: