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I'm implementing a VOIP application that uses pure Java. There is an echo problem that occurs when users do not use headsets (mostly on laptops with built-in microphones). What currently happens The nuts and bolts of the VOIP application is just the plain datalines of Java's media framework. Essentially, I'd like to perform some digital signal processing on audio data before I write it to the speaker for output. public synchronized void addAudioData(byte[] ayAudioData) { m_oBuffer.enqueue(ayAudioData); this.notify(); } As you can see the audio data arrives and is enqueued in a buffer. This is to cater for dodgy connections and to allow for different packet sizes. It also means I have access to as much audio data as I need for any fancy DSP operations before I play the audio data to the speaker line. I've managed one echo canceller that does work, however it requires a lot of interactive user input and I'd like to have an automatic echo canceller. Manual echo canceller public static byte[] removeEcho(int iDelaySamples, float fDecay, byte[] aySamples) { m_awDelayBuffer = new short[iDelaySamples]; m_aySamples = new byte[aySamples.length]; m_fDecay = (float) fDecay; System.out.println("Removing echo"); m_iDelayIndex = 0; System.out.println("Sample length:\t" + aySamples.length); for (int i = 0; i < aySamples.length; i += 2) { // update the sample short wOldSample = getSample(aySamples, i); // remove the echo short wNewSample = (short) (wOldSample - fDecay * m_awDelayBuffer[m_iDelayIndex]); setSample(m_aySamples, i, wNewSample); // update the delay buffer m_awDelayBuffer[m_iDelayIndex] = wNewSample; m_iDelayIndex++; if (m_iDelayIndex == m_awDelayBuffer.length) { m_iDelayIndex = 0; } } return m_aySamples; } </p

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