CODEWITHSUNDEEP
javaaudio
mr.M
mr.M

Reputation: 899

Performance issues with converting mp3 file input stream to byte output stream

I would like to extract byte array from a given mp3 file in order to apply fast fourier transform on the latter. The performed FFT will give me some features for my pet-project musical -- recommendation system.

I have written the following code to extract the bytes from a given mp3 file:

public class TrackSample {

private static byte[] readBytesInPredefinedFormat(TargetDataLine format, InputStream inStream) throws IOException {
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    byte[] buffer = new byte[8192];
    int bytesRead;
    while ((bytesRead = inStream.read(buffer)) > 0) {
        int count = format.read(buffer, 0, buffer.length);
        if (count > 0) {
            byteArrayOutputStream.write(buffer, 0, count);
        }
        byteArrayOutputStream.write(buffer, 0, bytesRead);
    }
    byte[] bytes = byteArrayOutputStream.toByteArray();
    byteArrayOutputStream.close();
    inStream.close();
    return bytes;
}

public static byte[] getTrackBytes(String pathToTrackSample) throws IOException, LineUnavailableException {
    FileInputStream fileInputStream = new FileInputStream(pathToTrackSample);
    final AudioFormat format = CurrentAudioFormat.getAudioFormat(); //Fill AudioFormat with the wanted settings
    DataLine.Info info = new DataLine.Info(TargetDataLine.class, format);

    TargetDataLine line = (TargetDataLine) AudioSystem.getLine(info);
    line.open(format);
    line.start();

    return readBytesInPredefinedFormat(line, fileInputStream);
    }
}

And the specified audio format is

public class CurrentAudioFormat {

    public static AudioFormat getAudioFormat(){
        float sampleRate = 44100;
        int sampleSizeInBits = 8;
        int channels = 1; //mono
        boolean signed = true;
        boolean bigEndian = true;
        return new AudioFormat(sampleRate, sampleSizeInBits, channels, signed, bigEndian);
    }
}

I tried to test this code on the following mp3 file:

File type ID:   MPG3
Num Tracks:     1
----
Data format:     2 ch,  44100 Hz, '.mp3' (0x00000000) 0 bits/channel, 0 bytes/packet, 1152 frames/packet, 0 bytes/frame
                no channel layout.
estimated duration: 104.176325 sec
audio bytes: 4167053
audio packets: 3988
bit rate: 320000 bits per second
packet size upper bound: 1052
maximum packet size: 1045
audio data file offset: 3169
optimized
audio 4591692 valid frames + 576 priming + 1908 remainder = 4594176

The system characteristics are:

It took roughly 5 minutes to extract the byte array from this mp3 file.

What are the possible bottlenecks and how can I improve them?

Upvotes: 0

Views: 1517

Answers (1)

gpasch
gpasch

Reputation: 2682

To read the bytes you just need

while ((bytesRead = inStream.read(buffer)) > -1) {
    byteArrayOutputStream.write(buffer, 0, bytesRead);
}

I dont know why you are reading twice.

To make sure that what you got is right try to resave it to a new audio file.

--

The standard way to read the audio file is 

AudioInputStream audioInputStream=null;
  try {
    audioInputStream=AudioSystem.getAudioInputStream(new File(file));
  }
  catch(UnsupportedAudioFileException auf) { auf.printStackTrace(); }

then you pass this audioInputStream to your reading method.

Upvotes: 2

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