зеркало из https://github.com/mozilla/gecko-dev.git
94 строки
2.9 KiB
C++
94 строки
2.9 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "AudioChannelFormat.h"
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#include <algorithm>
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namespace mozilla {
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uint32_t
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GetAudioChannelsSuperset(uint32_t aChannels1, uint32_t aChannels2)
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{
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return std::max(aChannels1, aChannels2);
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}
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/**
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* UpMixMatrix represents a conversion matrix by exploiting the fact that
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* each output channel comes from at most one input channel.
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*/
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struct UpMixMatrix {
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uint8_t mInputDestination[CUSTOM_CHANNEL_LAYOUTS];
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};
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static const UpMixMatrix
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gUpMixMatrices[CUSTOM_CHANNEL_LAYOUTS*(CUSTOM_CHANNEL_LAYOUTS - 1)/2] =
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{
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// Upmixes from mono
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{ { 0, 0 } },
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{ { 0, IGNORE, IGNORE } },
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{ { 0, 0, IGNORE, IGNORE } },
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{ { 0, IGNORE, IGNORE, IGNORE, IGNORE } },
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{ { IGNORE, IGNORE, 0, IGNORE, IGNORE, IGNORE } },
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// Upmixes from stereo
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{ { 0, 1, IGNORE } },
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{ { 0, 1, IGNORE, IGNORE } },
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{ { 0, 1, IGNORE, IGNORE, IGNORE } },
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{ { 0, 1, IGNORE, IGNORE, IGNORE, IGNORE } },
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// Upmixes from 3-channel
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{ { 0, 1, 2, IGNORE } },
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{ { 0, 1, 2, IGNORE, IGNORE } },
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{ { 0, 1, 2, IGNORE, IGNORE, IGNORE } },
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// Upmixes from quad
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{ { 0, 1, 2, 3, IGNORE } },
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{ { 0, 1, IGNORE, IGNORE, 2, 3 } },
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// Upmixes from 5-channel
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{ { 0, 1, 2, 3, 4, IGNORE } }
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};
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void
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AudioChannelsUpMix(nsTArray<const void*>* aChannelArray,
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uint32_t aOutputChannelCount,
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const void* aZeroChannel)
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{
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uint32_t inputChannelCount = aChannelArray->Length();
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uint32_t outputChannelCount =
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GetAudioChannelsSuperset(aOutputChannelCount, inputChannelCount);
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NS_ASSERTION(outputChannelCount > inputChannelCount,
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"No up-mix needed");
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MOZ_ASSERT(inputChannelCount > 0, "Bad number of channels");
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MOZ_ASSERT(outputChannelCount > 0, "Bad number of channels");
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aChannelArray->SetLength(outputChannelCount);
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if (inputChannelCount < CUSTOM_CHANNEL_LAYOUTS &&
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outputChannelCount <= CUSTOM_CHANNEL_LAYOUTS) {
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const UpMixMatrix& m = gUpMixMatrices[
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gMixingMatrixIndexByChannels[inputChannelCount - 1] +
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outputChannelCount - inputChannelCount - 1];
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const void* outputChannels[CUSTOM_CHANNEL_LAYOUTS];
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for (uint32_t i = 0; i < outputChannelCount; ++i) {
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uint8_t channelIndex = m.mInputDestination[i];
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if (channelIndex == IGNORE) {
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outputChannels[i] = aZeroChannel;
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} else {
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outputChannels[i] = aChannelArray->ElementAt(channelIndex);
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}
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}
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for (uint32_t i = 0; i < outputChannelCount; ++i) {
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aChannelArray->ElementAt(i) = outputChannels[i];
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}
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return;
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}
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for (uint32_t i = inputChannelCount; i < outputChannelCount; ++i) {
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aChannelArray->ElementAt(i) = aZeroChannel;
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}
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}
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} // namespace mozilla
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