зеркало из https://github.com/mozilla/gecko-dev.git
Bug 830707. Part 1: Add code for upmixing and downmixing following Web Audio's spec. r=jesup
--HG-- extra : rebase_source : 8cdcbc313fcd371b47ad194f2f0da1102e5e6240
This commit is contained in:
Robert O'Callahan
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5e332dc349
Коммит
df228b8f85
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/* -*- 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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enum {
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SURROUND_L,
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SURROUND_R,
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SURROUND_C,
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SURROUND_LFE,
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SURROUND_SL,
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SURROUND_SR
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};
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static const int CUSTOM_CHANNEL_LAYOUTS = 6;
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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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if (aChannels1 == 3 && aChannels2 == 4) {
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// quad layout has no center channel, but input has a center channel as well
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// as L and R, so we actually need a 5-channel layout here.
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return 5;
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}
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return std::max(aChannels1, aChannels2);
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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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NS_ASSERTION(inputChannelCount > 0, "Bad number of channels");
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NS_ASSERTION(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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const void* surroundChannels[CUSTOM_CHANNEL_LAYOUTS] =
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{ aZeroChannel, aZeroChannel, aZeroChannel,
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aZeroChannel, aZeroChannel, aZeroChannel
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};
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// First just map everything up to 5.1
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switch (inputChannelCount) {
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case 1:
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surroundChannels[SURROUND_C] = aChannelArray->ElementAt(0);
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break;
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case 2:
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surroundChannels[SURROUND_L] = aChannelArray->ElementAt(0);
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surroundChannels[SURROUND_R] = aChannelArray->ElementAt(1);
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break;
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case 3:
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surroundChannels[SURROUND_L] = aChannelArray->ElementAt(0);
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surroundChannels[SURROUND_R] = aChannelArray->ElementAt(1);
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surroundChannels[SURROUND_C] = aChannelArray->ElementAt(2);
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break;
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case 4:
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surroundChannels[SURROUND_L] = aChannelArray->ElementAt(0);
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surroundChannels[SURROUND_R] = aChannelArray->ElementAt(1);
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surroundChannels[SURROUND_SL] = aChannelArray->ElementAt(2);
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surroundChannels[SURROUND_SR] = aChannelArray->ElementAt(3);
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break;
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case 5:
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surroundChannels[SURROUND_L] = aChannelArray->ElementAt(0);
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surroundChannels[SURROUND_R] = aChannelArray->ElementAt(1);
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surroundChannels[SURROUND_C] = aChannelArray->ElementAt(2);
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surroundChannels[SURROUND_SL] = aChannelArray->ElementAt(3);
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surroundChannels[SURROUND_SR] = aChannelArray->ElementAt(4);
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break;
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}
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if (outputChannelCount < CUSTOM_CHANNEL_LAYOUTS) {
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// Map back to aOutputChannelCount
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switch (outputChannelCount) {
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case 2:
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// Upmix from mono, so use the center channel.
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aChannelArray->ElementAt(0) = surroundChannels[SURROUND_C];
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aChannelArray->ElementAt(1) = surroundChannels[SURROUND_C];
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break;
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case 3:
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aChannelArray->ElementAt(0) = surroundChannels[SURROUND_L];
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aChannelArray->ElementAt(1) = surroundChannels[SURROUND_R];
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aChannelArray->ElementAt(2) = surroundChannels[SURROUND_C];
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break;
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case 4:
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// We avoided this case up above.
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NS_ASSERTION(inputChannelCount != 3,
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"3->4 upmix not supported directly");
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if (inputChannelCount == 1) {
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// Output has no center channel, so map the mono to
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// L+R channels per Web Audio
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aChannelArray->ElementAt(0) = surroundChannels[SURROUND_C];
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aChannelArray->ElementAt(1) = surroundChannels[SURROUND_C];
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} else {
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aChannelArray->ElementAt(0) = surroundChannels[SURROUND_L];
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aChannelArray->ElementAt(1) = surroundChannels[SURROUND_R];
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}
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aChannelArray->ElementAt(2) = surroundChannels[SURROUND_SL];
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aChannelArray->ElementAt(3) = surroundChannels[SURROUND_SR];
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break;
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case 5:
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aChannelArray->ElementAt(0) = surroundChannels[SURROUND_L];
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aChannelArray->ElementAt(1) = surroundChannels[SURROUND_R];
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aChannelArray->ElementAt(2) = surroundChannels[SURROUND_C];
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aChannelArray->ElementAt(3) = surroundChannels[SURROUND_SL];
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aChannelArray->ElementAt(4) = surroundChannels[SURROUND_SR];
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}
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return;
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}
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memcpy(aChannelArray->Elements(), surroundChannels, sizeof(surroundChannels));
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inputChannelCount = CUSTOM_CHANNEL_LAYOUTS;
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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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/**
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* DownMixMatrix represents a conversion matrix efficiently by exploiting the
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* fact that each input channel contributes to at most one output channel,
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* except possibly for the C input channel in layouts that have one. Also,
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* every input channel is multiplied by the same coefficient for every output
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* channel it contributes to.
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*/
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struct DownMixMatrix {
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// Every input channel c is copied to output channel mInputDestination[c]
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// after multiplying by mInputCoefficient[c].
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uint8_t mInputDestination[CUSTOM_CHANNEL_LAYOUTS];
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// If not IGNORE, then the C channel is copied to this output channel after
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// multiplying by its coefficient.
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uint8_t mCExtraDestination;
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float mInputCoefficient[CUSTOM_CHANNEL_LAYOUTS];
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};
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static const int IGNORE = CUSTOM_CHANNEL_LAYOUTS;
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static const float IGNORE_F = 0.0f;
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static const DownMixMatrix
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gDownMixMatrices[CUSTOM_CHANNEL_LAYOUTS*(CUSTOM_CHANNEL_LAYOUTS - 1)/2] =
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{
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// Downmixes to mono
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{ { 0, 0 }, IGNORE, { 0.5f, 0.5f } },
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{ { 0, 0, 0 }, IGNORE, { 0.3333f, 0.3333f, 0.3333f } },
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{ { 0, 0, 0, 0 }, IGNORE, { 0.25f, 0.25f, 0.25f, 0.25f } },
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{ { 0, 0, 0, 0, 0 }, IGNORE, { 0.7071f, 0.7071f, 1.0f, 0.5f, 0.5f } },
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{ { 0, 0, 0, IGNORE, 0, 0 }, IGNORE, { 0.7071f, 0.7071f, 1.0f, IGNORE_F, 0.5f, 0.5f } },
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// Downmixes to stereo
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{ { 0, 1, 0 }, 1, { 1.0f, 1.0f, 0.7071f } },
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{ { 0, 1, 0, 1 }, IGNORE, { 0.5f, 0.5f, 0.5f, 0.5f } },
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{ { 0, 1, 0, 0, 1 }, 1, { 1.0f, 1.0f, 0.7071f, 0.7071f, 0.7071f } },
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{ { 0, 1, 0, IGNORE, 0, 1 }, 1, { 1.0f, 1.0f, 0.7071f, IGNORE_F, 0.7071f, 0.7071f } },
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// Downmixes to 3-channel
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{ { 0, 1, 0, 1 }, IGNORE, { 0.25f, 0.25f, 0.25f, 0.25f } },
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{ { 0, 1, 2, 0, 1 }, IGNORE, { 0.5f, 0.5f, 1.0f, 0.5f, 0.5f } },
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{ { 0, 1, 2, IGNORE, 0, 1 }, IGNORE, { 0.5f, 0.5f, 1.0f, IGNORE_F, 0.5f, 0.5f } },
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// Downmixes to quad
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{ { 0, 1, 0, 2, 3 }, 1, { 1.0f, 1.0f, 0.7071f, 1.0f, 1.0f } },
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{ { 0, 1, 0, IGNORE, 2, 3 }, 1, { 1.0f, 1.0f, 0.7071f, IGNORE_F, 1.0f, 1.0f } },
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// Downmixes to 5-channel
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{ { 0, 1, 2, IGNORE, 3, 4 }, IGNORE, { 1.0f, 1.0f, 1.0f, IGNORE_F, 1.0f, 1.0f } }
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};
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static const int gDownMixMatrixIndexByOutputChannels[CUSTOM_CHANNEL_LAYOUTS - 1] =
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{ 0, 5, 9, 12, 14 };
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void
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AudioChannelsDownMix(const nsTArray<const void*>& aChannelArray,
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float** aOutputChannels,
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uint32_t aOutputChannelCount,
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uint32_t aDuration)
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{
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uint32_t inputChannelCount = aChannelArray.Length();
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const void* const* inputChannels = aChannelArray.Elements();
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NS_ASSERTION(inputChannelCount > aOutputChannelCount, "Nothing to do");
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if (aOutputChannelCount >= 6) {
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// Just drop the unknown channels.
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for (uint32_t o = 0; o < aOutputChannelCount; ++o) {
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memcpy(aOutputChannels[o], inputChannels[o], aDuration*sizeof(float));
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}
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return;
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}
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// Ignore unknown channels, they're just dropped.
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inputChannelCount = std::min<uint32_t>(6, inputChannelCount);
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const DownMixMatrix& m = gDownMixMatrices[
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gDownMixMatrixIndexByOutputChannels[aOutputChannelCount - 1] +
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inputChannelCount - aOutputChannelCount - 1];
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// This is slow, but general. We can define custom code for special
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// cases later.
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for (uint32_t s = 0; s < aDuration; ++s) {
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// Reserve an extra junk channel at the end for the cases where we
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// want an input channel to contribute to nothing
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float outputChannels[CUSTOM_CHANNEL_LAYOUTS];
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memset(outputChannels, 0, sizeof(float)*(CUSTOM_CHANNEL_LAYOUTS - 1));
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for (uint32_t c = 0; c < inputChannelCount; ++c) {
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outputChannels[m.mInputDestination[c]] +=
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m.mInputCoefficient[c]*(static_cast<const float*>(inputChannels[c]))[s];
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}
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// Utilize the fact that in every layout, C is the third channel.
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if (m.mCExtraDestination != IGNORE) {
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outputChannels[m.mCExtraDestination] +=
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m.mInputCoefficient[SURROUND_C]*(static_cast<const float*>(inputChannels[SURROUND_C]))[s];
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}
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for (uint32_t c = 0; c < aOutputChannelCount; ++c) {
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aOutputChannels[c][s] = outputChannels[c];
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}
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}
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}
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}
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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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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
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef MOZILLA_AUDIOCHANNELFORMAT_H_
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#define MOZILLA_AUDIOCHANNELFORMAT_H_
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#include "nsTArray.h"
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namespace mozilla {
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/*
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* This file provides utilities for upmixing and downmixing channels.
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*
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* The channel layouts, upmixing and downmixing are consistent with the
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* Web Audio spec.
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*
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* Channel layouts for up to 6 channels:
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* mono { M }
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* stereo { L, R }
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* { L, R, C }
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* quad { L, R, SL, SR }
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* { L, R, C, SL, SR }
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* 5.1 { L, R, C, LFE, SL, SR }
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*
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* Only 1, 2, 4 and 6 are currently defined in Web Audio.
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*/
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/**
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* Return a channel count whose channel layout includes all the channels from
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* aChannels1 and aChannels2.
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*/
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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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* Given an array of input channel data, and an output channel count,
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* replaces the array with an array of upmixed channels.
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* This shuffles the array and may set some channel buffers to aZeroChannel.
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* Don't call this with input count >= output count.
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* This may return *more* channels than requested. In that case, downmixing
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* is required to to get to aOutputChannelCount. (This is how we handle
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* odd cases like 3 -> 4 upmixing.)
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* If aChannelArray.Length() was the input to one of a series of
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* GetAudioChannelsSuperset calls resulting in aOutputChannelCount,
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* no downmixing will be required.
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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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* Given an array of input channels (which must be float format!),
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* downmix to aOutputChannelCount, and copy the results to the
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* channel buffers in aOutputChannels.
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* Don't call this with input count <= output count.
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*/
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void
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AudioChannelsDownMix(const nsTArray<const void*>& aChannelArray,
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float** aOutputChannels,
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uint32_t aOutputChannelCount,
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uint32_t aDuration);
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// A version of AudioChannelsDownMix that downmixes int16_ts may be required.
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} // namespace mozilla
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#endif /* MOZILLA_AUDIOCHANNELFORMAT_H_ */
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@ -18,6 +18,7 @@ endif # !_MSC_VER
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EXPORTS = \
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AbstractMediaDecoder.h \
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AudioChannelFormat.h \
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AudioSampleFormat.h \
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AudioSegment.h \
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BufferMediaResource.h \
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@ -44,6 +45,7 @@ EXPORTS = \
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$(NULL)
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CPPSRCS = \
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AudioChannelFormat.cpp \
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AudioSegment.cpp \
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DecoderTraits.cpp \
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FileBlockCache.cpp \
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