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diff --git a/dom/media/AudioSampleFormat.h b/dom/media/AudioSampleFormat.h
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef MOZILLA_AUDIOSAMPLEFORMAT_H_
+#define MOZILLA_AUDIOSAMPLEFORMAT_H_
+
+#include "mozilla/Assertions.h"
+#include <algorithm>
+
+namespace mozilla {
+
+/**
+ * Audio formats supported in MediaTracks and media elements.
+ *
+ * Only one of these is supported by AudioStream, and that is determined
+ * at compile time (roughly, FLOAT32 on desktops, S16 on mobile). Media decoders
+ * produce that format only; queued AudioData always uses that format.
+ */
+enum AudioSampleFormat {
+ // Silence: format will be chosen later
+ AUDIO_FORMAT_SILENCE,
+ // Native-endian signed 16-bit audio samples
+ AUDIO_FORMAT_S16,
+ // Signed 32-bit float samples
+ AUDIO_FORMAT_FLOAT32,
+// The format used for output by AudioStream.
+#ifdef MOZ_SAMPLE_TYPE_S16
+ AUDIO_OUTPUT_FORMAT = AUDIO_FORMAT_S16
+#else
+ AUDIO_OUTPUT_FORMAT = AUDIO_FORMAT_FLOAT32
+#endif
+};
+
+enum { MAX_AUDIO_SAMPLE_SIZE = sizeof(float) };
+
+template <AudioSampleFormat Format>
+class AudioSampleTraits;
+
+template <>
+class AudioSampleTraits<AUDIO_FORMAT_FLOAT32> {
+ public:
+ typedef float Type;
+};
+template <>
+class AudioSampleTraits<AUDIO_FORMAT_S16> {
+ public:
+ typedef int16_t Type;
+};
+
+typedef AudioSampleTraits<AUDIO_OUTPUT_FORMAT>::Type AudioDataValue;
+
+template <typename T>
+class AudioSampleTypeToFormat;
+
+template <>
+class AudioSampleTypeToFormat<float> {
+ public:
+ static const AudioSampleFormat Format = AUDIO_FORMAT_FLOAT32;
+};
+
+template <>
+class AudioSampleTypeToFormat<short> {
+ public:
+ static const AudioSampleFormat Format = AUDIO_FORMAT_S16;
+};
+
+// Single-sample conversion
+/*
+ * Use "2^N" conversion since it's simple, fast, "bit transparent", used by
+ * many other libraries and apparently behaves reasonably.
+ * http://blog.bjornroche.com/2009/12/int-float-int-its-jungle-out-there.html
+ * http://blog.bjornroche.com/2009/12/linearity-and-dynamic-range-in-int.html
+ */
+inline float AudioSampleToFloat(float aValue) { return aValue; }
+inline float AudioSampleToFloat(int16_t aValue) { return aValue / 32768.0f; }
+inline float AudioSampleToFloat(int32_t aValue) {
+ return aValue / (float)(1U << 31);
+}
+
+template <typename T>
+T FloatToAudioSample(float aValue);
+
+template <>
+inline float FloatToAudioSample<float>(float aValue) {
+ return aValue;
+}
+template <>
+inline int16_t FloatToAudioSample<int16_t>(float aValue) {
+ float v = aValue * 32768.0f;
+ float clamped = std::max(-32768.0f, std::min(32767.0f, v));
+ return int16_t(clamped);
+}
+
+template <typename T>
+T UInt8bitToAudioSample(uint8_t aValue);
+
+template <>
+inline float UInt8bitToAudioSample<float>(uint8_t aValue) {
+ return aValue * (static_cast<float>(2) / UINT8_MAX) - static_cast<float>(1);
+}
+template <>
+inline int16_t UInt8bitToAudioSample<int16_t>(uint8_t aValue) {
+ return static_cast<int16_t>((aValue << 8) + aValue + INT16_MIN);
+}
+
+template <typename T>
+T IntegerToAudioSample(int16_t aValue);
+
+template <>
+inline float IntegerToAudioSample<float>(int16_t aValue) {
+ return aValue / 32768.0f;
+}
+template <>
+inline int16_t IntegerToAudioSample<int16_t>(int16_t aValue) {
+ return aValue;
+}
+
+template <typename T>
+T Int24bitToAudioSample(int32_t aValue);
+
+template <>
+inline float Int24bitToAudioSample<float>(int32_t aValue) {
+ return aValue / static_cast<float>(1 << 23);
+}
+template <>
+inline int16_t Int24bitToAudioSample<int16_t>(int32_t aValue) {
+ return static_cast<int16_t>(aValue / 256);
+}
+
+template <typename SrcT, typename DstT>
+inline void ConvertAudioSample(SrcT aIn, DstT& aOut);
+
+template <>
+inline void ConvertAudioSample(int16_t aIn, int16_t& aOut) {
+ aOut = aIn;
+}
+
+template <>
+inline void ConvertAudioSample(int16_t aIn, float& aOut) {
+ aOut = AudioSampleToFloat(aIn);
+}
+
+template <>
+inline void ConvertAudioSample(float aIn, float& aOut) {
+ aOut = aIn;
+}
+
+template <>
+inline void ConvertAudioSample(float aIn, int16_t& aOut) {
+ aOut = FloatToAudioSample<int16_t>(aIn);
+}
+
+// Sample buffer conversion
+
+template <typename From, typename To>
+inline void ConvertAudioSamples(const From* aFrom, To* aTo, int aCount) {
+ for (int i = 0; i < aCount; ++i) {
+ aTo[i] = FloatToAudioSample<To>(AudioSampleToFloat(aFrom[i]));
+ }
+}
+inline void ConvertAudioSamples(const int16_t* aFrom, int16_t* aTo,
+ int aCount) {
+ memcpy(aTo, aFrom, sizeof(*aTo) * aCount);
+}
+inline void ConvertAudioSamples(const float* aFrom, float* aTo, int aCount) {
+ memcpy(aTo, aFrom, sizeof(*aTo) * aCount);
+}
+
+// Sample buffer conversion with scale
+
+template <typename From, typename To>
+inline void ConvertAudioSamplesWithScale(const From* aFrom, To* aTo, int aCount,
+ float aScale) {
+ if (aScale == 1.0f) {
+ ConvertAudioSamples(aFrom, aTo, aCount);
+ return;
+ }
+ for (int i = 0; i < aCount; ++i) {
+ aTo[i] = FloatToAudioSample<To>(AudioSampleToFloat(aFrom[i]) * aScale);
+ }
+}
+inline void ConvertAudioSamplesWithScale(const int16_t* aFrom, int16_t* aTo,
+ int aCount, float aScale) {
+ if (aScale == 1.0f) {
+ ConvertAudioSamples(aFrom, aTo, aCount);
+ return;
+ }
+ if (0.0f <= aScale && aScale < 1.0f) {
+ int32_t scale = int32_t((1 << 16) * aScale);
+ for (int i = 0; i < aCount; ++i) {
+ aTo[i] = int16_t((int32_t(aFrom[i]) * scale) >> 16);
+ }
+ return;
+ }
+ for (int i = 0; i < aCount; ++i) {
+ aTo[i] = FloatToAudioSample<int16_t>(AudioSampleToFloat(aFrom[i]) * aScale);
+ }
+}
+
+// In place audio sample scaling.
+inline void ScaleAudioSamples(float* aBuffer, int aCount, float aScale) {
+ for (int32_t i = 0; i < aCount; ++i) {
+ aBuffer[i] *= aScale;
+ }
+}
+
+inline void ScaleAudioSamples(short* aBuffer, int aCount, float aScale) {
+ int32_t volume = int32_t((1 << 16) * aScale);
+ for (int32_t i = 0; i < aCount; ++i) {
+ aBuffer[i] = short((int32_t(aBuffer[i]) * volume) >> 16);
+ }
+}
+
+inline const void* AddAudioSampleOffset(const void* aBase,
+ AudioSampleFormat aFormat,
+ int32_t aOffset) {
+ static_assert(AUDIO_FORMAT_S16 == 1, "Bad constant");
+ static_assert(AUDIO_FORMAT_FLOAT32 == 2, "Bad constant");
+ MOZ_ASSERT(aFormat == AUDIO_FORMAT_S16 || aFormat == AUDIO_FORMAT_FLOAT32);
+
+ return static_cast<const uint8_t*>(aBase) + aFormat * 2 * aOffset;
+}
+
+} // namespace mozilla
+
+#endif /* MOZILLA_AUDIOSAMPLEFORMAT_H_ */