/* -*- 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 "nsAlgorithm.h" #include <algorithm> namespace mozilla { /** * Audio formats supported in MediaStreams 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 { // Native-endian signed 16-bit audio samples AUDIO_FORMAT_S16, // Signed 32-bit float samples AUDIO_FORMAT_FLOAT32, // Silence: format will be chosen later AUDIO_FORMAT_SILENCE, // 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 (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 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 == 0, "Bad constant"); static_assert(AUDIO_FORMAT_FLOAT32 == 1, "Bad constant"); NS_ASSERTION(aFormat == AUDIO_FORMAT_S16 || aFormat == AUDIO_FORMAT_FLOAT32, "Unknown format"); return static_cast<const uint8_t*>(aBase) + (aFormat + 1)*2*aOffset; } } // namespace mozilla #endif /* MOZILLA_AUDIOSAMPLEFORMAT_H_ */