long TimePermRingBuffer::timeSpan() { return m_period * bufferSize(); }
void JavaScriptAudioNode::process(size_t framesToProcess) { // Discussion about inputs and outputs: // As in other AudioNodes, JavaScriptAudioNode uses an AudioBus for its input and output (see inputBus and outputBus below). // Additionally, there is a double-buffering for input and output which is exposed directly to JavaScript (see inputBuffer and outputBuffer below). // This node is the producer for inputBuffer and the consumer for outputBuffer. // The JavaScript code is the consumer of inputBuffer and the producer for outputBuffer. // Get input and output busses. AudioBus* inputBus = this->input(0)->bus(); AudioBus* outputBus = this->output(0)->bus(); // Get input and output buffers. We double-buffer both the input and output sides. unsigned doubleBufferIndex = this->doubleBufferIndex(); bool isDoubleBufferIndexGood = doubleBufferIndex < 2 && doubleBufferIndex < m_inputBuffers.size() && doubleBufferIndex < m_outputBuffers.size(); ASSERT(isDoubleBufferIndexGood); if (!isDoubleBufferIndexGood) return; AudioBuffer* inputBuffer = m_inputBuffers[doubleBufferIndex].get(); AudioBuffer* outputBuffer = m_outputBuffers[doubleBufferIndex].get(); // Check the consistency of input and output buffers. bool buffersAreGood = inputBuffer && outputBuffer && bufferSize() == inputBuffer->length() && bufferSize() == outputBuffer->length() && m_bufferReadWriteIndex + framesToProcess <= bufferSize(); ASSERT(buffersAreGood); if (!buffersAreGood) return; // We assume that bufferSize() is evenly divisible by framesToProcess - should always be true, but we should still check. bool isFramesToProcessGood = framesToProcess && bufferSize() >= framesToProcess && !(bufferSize() % framesToProcess); ASSERT(isFramesToProcessGood); if (!isFramesToProcessGood) return; unsigned numberOfInputChannels = inputBus->numberOfChannels(); bool channelsAreGood = (numberOfInputChannels == 1 || numberOfInputChannels == 2) && outputBus->numberOfChannels() == 2; ASSERT(channelsAreGood); if (!channelsAreGood) return; float* sourceL = inputBus->channel(0)->data(); float* sourceR = numberOfInputChannels > 1 ? inputBus->channel(1)->data() : 0; float* destinationL = outputBus->channel(0)->data(); float* destinationR = outputBus->channel(1)->data(); // Copy from the input to the input buffer. See "buffersAreGood" check above for safety. size_t bytesToCopy = sizeof(float) * framesToProcess; memcpy(inputBuffer->getChannelData(0)->data() + m_bufferReadWriteIndex, sourceL, bytesToCopy); if (numberOfInputChannels == 2) memcpy(inputBuffer->getChannelData(1)->data() + m_bufferReadWriteIndex, sourceR, bytesToCopy); else if (numberOfInputChannels == 1) { // If the input is mono, then also copy the mono input to the right channel of the AudioBuffer which the AudioProcessingEvent uses. // FIXME: it is likely the audio API will evolve to present an AudioBuffer with the same number of channels as our input. memcpy(inputBuffer->getChannelData(1)->data() + m_bufferReadWriteIndex, sourceL, bytesToCopy); } // Copy from the output buffer to the output. See "buffersAreGood" check above for safety. memcpy(destinationL, outputBuffer->getChannelData(0)->data() + m_bufferReadWriteIndex, bytesToCopy); memcpy(destinationR, outputBuffer->getChannelData(1)->data() + m_bufferReadWriteIndex, bytesToCopy); // Update the buffering index. m_bufferReadWriteIndex = (m_bufferReadWriteIndex + framesToProcess) % bufferSize(); // m_bufferReadWriteIndex will wrap back around to 0 when the current input and output buffers are full. // When this happens, fire an event and swap buffers. if (!m_bufferReadWriteIndex) { // Avoid building up requests on the main thread to fire process events when they're not being handled. // This could be a problem if the main thread is very busy doing other things and is being held up handling previous requests. if (m_isRequestOutstanding) { // We're late in handling the previous request. The main thread must be very busy. // The best we can do is clear out the buffer ourself here. outputBuffer->zero(); } else { // Reference ourself so we don't accidentally get deleted before fireProcessEvent() gets called. ref(); // Fire the event on the main thread, not this one (which is the realtime audio thread). m_doubleBufferIndexForEvent = m_doubleBufferIndex; m_isRequestOutstanding = true; callOnMainThread(fireProcessEventDispatch, this); } swapBuffers(); } }