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Diffstat (limited to 'dom/media/AudioSampleFormat.h')
| -rw-r--r-- | dom/media/AudioSampleFormat.h | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/dom/media/AudioSampleFormat.h b/dom/media/AudioSampleFormat.h new file mode 100644 index 0000000000..f53021262b --- /dev/null +++ b/dom/media/AudioSampleFormat.h @@ -0,0 +1,228 @@ +/* -*- 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_ */ |