An older Java-program I maintain comes with a bunch of little .au files to play different sounds. All of these are identified by file as: Sun/NeXT audio data: 8-bit ISDN mu-law, mono, 8000 Hz.

The program fails to play them complaining of unsuitable format. Having modified its format-selection to dump debug information, I came up with the following Java-code:

  protected static AudioFormat getFormatForPlaying(byte [] audioData)
      throws UnsupportedAudioFileException, IOException{
    ByteArrayInputStream bais = new ByteArrayInputStream(audioData);
    AudioFormat format = AudioSystem.getAudioFileFormat(bais).getFormat();
    DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);

    if (AudioSystem.isLineSupported(info)) {
      System.err.println("Audio format ``" + format + "'' can be used straight");
      return format;
    }
    System.err.println("Audio format ``" + format + "'' can not be used straight");

    AudioFormat[] possibleFormats = AudioSystem.getTargetFormats(
      AudioFormat.Encoding.PCM_SIGNED, format);

    for (AudioFormat newFormat : possibleFormats) {
      info = new DataLine.Info(SourceDataLine.class, newFormat);
      if (AudioSystem.isLineSupported(info)) {
         System.err.println("Will try audio format " + newFormat + " instead of " + format);
         return newFormat;
      }
      System.err.println("Format ``" + newFormat + "'' cannot be used");
    }
    throw new UnsupportedAudioFileException("No suitable audio format among " +
      possibleFormats.length + " possibilities");
  }

At run time I get the following printed to stderr now:

Audio format ``ULAW 8000.0 Hz, 8 bit, mono, 1 bytes/frame, '' can not be used straight
Format ``PCM_SIGNED 8000.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian'' cannot be used
Format ``PCM_SIGNED 8000.0 Hz, 16 bit, mono, 2 bytes/frame, big-endian'' cannot be used
javax.sound.sampled.UnsupportedAudioFileException: No suitable audio format among 2 possibilities

Google's AI is telling me, that just means, my actual sound hardware cannot play such low rate audio, and that's that -- the sound library included in Java cannot modify the sampling rate for me, period...

Is that really true? If so, is there an easy way out -- such as by using some known and common conversion package?

(When I play the same sound-files using mplayer, for example, it reports converting them from 8kHz to 16kHz automatically.)