Opus audio File to Wav conversion

Question

Good morning,

I'm trying to convert an opus audio file to wav file on Java.

I've been seeking different solutions with different libraries, and finally I've found a possible solution. My problem is output wav audio file has a lot of noise, like distortion, and I don't know how to solve this.

Here is my code:

public void OpusToWav() {

    JOpusFile inFile = new JOpusFile(input_File);
    AudioFormat sourceFormat = inFile.format;
    JOpusDecodable decoder; // com.glester.jopus.JOpusDecodable
    ByteBuffer sampleBuffer;
    WaveFileWriter wavWriter; // net.sourceforge.jaad.util.wav.WaveFileWriter

    byte [] buf;
    int bytesRead = 0;

    try {
        decoder = JOpusBufferFile.loadFromFile(input_File);
        sampleBuffer = decoder.getSampleBuffer();
        wavWriter = new WaveFileWriter(outputFile, 44100, sourceFormat.getChannels(), sourceFormat.getSampleSizeInBits());

        buf = new byte[sampleBuffer.capacity()];

        while(true) {
            bytesRead = decoder.read();
            if(bytesRead <= 0) break;
            sampleBuffer.get(buf);

            // Its needed to reduce sample volume in byte array??

            wavWriter.write(buf, 0, bytesRead);
        }

        wavWriter.close();
        decoder.close();
        inFile.close();
    } catch(URISyntaxException | IOException e) {
        System.out.println("Error decoding opus file --> " +  e.getMessage());
    }
}

I've tried to modify sample volume in output byte array, but problem was still there.

Any idea how to solve this?

P.D: I have tried with Concentus library as well, but no difference.

Answer 1

Try this: https://github.com/louisyonge/opus_android

Encode from opus to wav

OpusTool oTool = new OpusTool();
oTool.decode(fileName,fileNameOut, null);
oTool.encode(fileName, fileNameOut, null);

Answer 2

There’s no Java library to do this, but you can use the opus-tools and execute opusdec using Java ProcessBuilder. See my answer or this article to learn how to use the ProcessBuilder.

Answer 3

I'm guessing it's because you are reading the audio data as bytes with bytesRead = decoder.read() and either 1) the output is getting clamped to 8 bits of depth (not sure why it would do that) or 2) the endianness or byte offset is getting mixed up somehow.

Concentus does have a method to decode opus packets into 16-bit short values which unambiguously represent the waveform. Only problem is that support for reading ogg packets from a .opus file was never really completed. However it can be done by modifying VorbisJava slightly to make it support opus decoding.