| /* |
| * Copyright (C) 2011 Google Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of |
| * its contributors may be used to endorse or promote products derived |
| * from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
| * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY |
| * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "config.h" |
| |
| #if ENABLE(WEB_AUDIO) |
| |
| #include "platform/audio/MultiChannelResampler.h" |
| |
| #include "platform/audio/AudioBus.h" |
| |
| namespace WebCore { |
| |
| namespace { |
| |
| // ChannelProvider provides a single channel of audio data (one channel at a time) for each channel |
| // of data provided to us in a multi-channel provider. |
| |
| class ChannelProvider : public AudioSourceProvider { |
| public: |
| ChannelProvider(AudioSourceProvider* multiChannelProvider, unsigned numberOfChannels) |
| : m_multiChannelProvider(multiChannelProvider) |
| , m_numberOfChannels(numberOfChannels) |
| , m_currentChannel(0) |
| , m_framesToProcess(0) |
| { |
| } |
| |
| // provideInput() will be called once for each channel, starting with the first channel. |
| // Each time it's called, it will provide the next channel of data. |
| virtual void provideInput(AudioBus* bus, size_t framesToProcess) |
| { |
| bool isBusGood = bus && bus->numberOfChannels() == 1; |
| ASSERT(isBusGood); |
| if (!isBusGood) |
| return; |
| |
| // Get the data from the multi-channel provider when the first channel asks for it. |
| // For subsequent channels, we can just dish out the channel data from that (stored in m_multiChannelBus). |
| if (!m_currentChannel) { |
| m_framesToProcess = framesToProcess; |
| m_multiChannelBus = AudioBus::create(m_numberOfChannels, framesToProcess); |
| m_multiChannelProvider->provideInput(m_multiChannelBus.get(), framesToProcess); |
| } |
| |
| // All channels must ask for the same amount. This should always be the case, but let's just make sure. |
| bool isGood = m_multiChannelBus.get() && framesToProcess == m_framesToProcess; |
| ASSERT(isGood); |
| if (!isGood) |
| return; |
| |
| // Copy the channel data from what we received from m_multiChannelProvider. |
| ASSERT(m_currentChannel <= m_numberOfChannels); |
| if (m_currentChannel < m_numberOfChannels) { |
| memcpy(bus->channel(0)->mutableData(), m_multiChannelBus->channel(m_currentChannel)->data(), sizeof(float) * framesToProcess); |
| ++m_currentChannel; |
| } |
| } |
| |
| private: |
| AudioSourceProvider* m_multiChannelProvider; |
| RefPtr<AudioBus> m_multiChannelBus; |
| unsigned m_numberOfChannels; |
| unsigned m_currentChannel; |
| size_t m_framesToProcess; // Used to verify that all channels ask for the same amount. |
| }; |
| |
| } // namespace |
| |
| MultiChannelResampler::MultiChannelResampler(double scaleFactor, unsigned numberOfChannels) |
| : m_numberOfChannels(numberOfChannels) |
| { |
| // Create each channel's resampler. |
| for (unsigned channelIndex = 0; channelIndex < numberOfChannels; ++channelIndex) |
| m_kernels.append(adoptPtr(new SincResampler(scaleFactor))); |
| } |
| |
| void MultiChannelResampler::process(AudioSourceProvider* provider, AudioBus* destination, size_t framesToProcess) |
| { |
| // The provider can provide us with multi-channel audio data. But each of our single-channel resamplers (kernels) |
| // below requires a provider which provides a single unique channel of data. |
| // channelProvider wraps the original multi-channel provider and dishes out one channel at a time. |
| ChannelProvider channelProvider(provider, m_numberOfChannels); |
| |
| for (unsigned channelIndex = 0; channelIndex < m_numberOfChannels; ++channelIndex) { |
| // Depending on the sample-rate scale factor, and the internal buffering used in a SincResampler |
| // kernel, this call to process() will only sometimes call provideInput() on the channelProvider. |
| // However, if it calls provideInput() for the first channel, then it will call it for the remaining |
| // channels, since they all buffer in the same way and are processing the same number of frames. |
| m_kernels[channelIndex]->process(&channelProvider, |
| destination->channel(channelIndex)->mutableData(), |
| framesToProcess); |
| } |
| } |
| |
| } // namespace WebCore |
| |
| #endif // ENABLE(WEB_AUDIO) |