1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/content/media/AudioSampleFormat.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,183 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim:set ts=2 sw=2 sts=2 et cindent: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +#ifndef MOZILLA_AUDIOSAMPLEFORMAT_H_
1.10 +#define MOZILLA_AUDIOSAMPLEFORMAT_H_
1.11 +
1.12 +#include "nsAlgorithm.h"
1.13 +#include <algorithm>
1.14 +
1.15 +namespace mozilla {
1.16 +
1.17 +/**
1.18 + * Audio formats supported in MediaStreams and media elements.
1.19 + *
1.20 + * Only one of these is supported by AudioStream, and that is determined
1.21 + * at compile time (roughly, FLOAT32 on desktops, S16 on mobile). Media decoders
1.22 + * produce that format only; queued AudioData always uses that format.
1.23 + */
1.24 +enum AudioSampleFormat
1.25 +{
1.26 + // Native-endian signed 16-bit audio samples
1.27 + AUDIO_FORMAT_S16,
1.28 + // Signed 32-bit float samples
1.29 + AUDIO_FORMAT_FLOAT32,
1.30 + // Silence: format will be chosen later
1.31 + AUDIO_FORMAT_SILENCE,
1.32 + // The format used for output by AudioStream.
1.33 +#ifdef MOZ_SAMPLE_TYPE_S16
1.34 + AUDIO_OUTPUT_FORMAT = AUDIO_FORMAT_S16
1.35 +#else
1.36 + AUDIO_OUTPUT_FORMAT = AUDIO_FORMAT_FLOAT32
1.37 +#endif
1.38 +};
1.39 +
1.40 +enum {
1.41 + MAX_AUDIO_SAMPLE_SIZE = sizeof(float)
1.42 +};
1.43 +
1.44 +template <AudioSampleFormat Format> class AudioSampleTraits;
1.45 +
1.46 +template <> class AudioSampleTraits<AUDIO_FORMAT_FLOAT32> {
1.47 +public:
1.48 + typedef float Type;
1.49 +};
1.50 +template <> class AudioSampleTraits<AUDIO_FORMAT_S16> {
1.51 +public:
1.52 + typedef int16_t Type;
1.53 +};
1.54 +
1.55 +typedef AudioSampleTraits<AUDIO_OUTPUT_FORMAT>::Type AudioDataValue;
1.56 +
1.57 +template<typename T> class AudioSampleTypeToFormat;
1.58 +
1.59 +template <> class AudioSampleTypeToFormat<float> {
1.60 +public:
1.61 + static const AudioSampleFormat Format = AUDIO_FORMAT_FLOAT32;
1.62 +};
1.63 +
1.64 +template <> class AudioSampleTypeToFormat<short> {
1.65 +public:
1.66 + static const AudioSampleFormat Format = AUDIO_FORMAT_S16;
1.67 +};
1.68 +
1.69 +// Single-sample conversion
1.70 +/*
1.71 + * Use "2^N" conversion since it's simple, fast, "bit transparent", used by
1.72 + * many other libraries and apparently behaves reasonably.
1.73 + * http://blog.bjornroche.com/2009/12/int-float-int-its-jungle-out-there.html
1.74 + * http://blog.bjornroche.com/2009/12/linearity-and-dynamic-range-in-int.html
1.75 + */
1.76 +inline float
1.77 +AudioSampleToFloat(float aValue)
1.78 +{
1.79 + return aValue;
1.80 +}
1.81 +inline float
1.82 +AudioSampleToFloat(int16_t aValue)
1.83 +{
1.84 + return aValue/32768.0f;
1.85 +}
1.86 +
1.87 +template <typename T> T FloatToAudioSample(float aValue);
1.88 +
1.89 +template <> inline float
1.90 +FloatToAudioSample<float>(float aValue)
1.91 +{
1.92 + return aValue;
1.93 +}
1.94 +template <> inline int16_t
1.95 +FloatToAudioSample<int16_t>(float aValue)
1.96 +{
1.97 + float v = aValue*32768.0f;
1.98 + float clamped = std::max(-32768.0f, std::min(32767.0f, v));
1.99 + return int16_t(clamped);
1.100 +}
1.101 +
1.102 +// Sample buffer conversion
1.103 +
1.104 +template <typename From, typename To> inline void
1.105 +ConvertAudioSamples(const From* aFrom, To* aTo, int aCount)
1.106 +{
1.107 + for (int i = 0; i < aCount; ++i) {
1.108 + aTo[i] = FloatToAudioSample<To>(AudioSampleToFloat(aFrom[i]));
1.109 + }
1.110 +}
1.111 +inline void
1.112 +ConvertAudioSamples(const int16_t* aFrom, int16_t* aTo, int aCount)
1.113 +{
1.114 + memcpy(aTo, aFrom, sizeof(*aTo)*aCount);
1.115 +}
1.116 +inline void
1.117 +ConvertAudioSamples(const float* aFrom, float* aTo, int aCount)
1.118 +{
1.119 + memcpy(aTo, aFrom, sizeof(*aTo)*aCount);
1.120 +}
1.121 +
1.122 +// Sample buffer conversion with scale
1.123 +
1.124 +template <typename From, typename To> inline void
1.125 +ConvertAudioSamplesWithScale(const From* aFrom, To* aTo, int aCount, float aScale)
1.126 +{
1.127 + if (aScale == 1.0f) {
1.128 + ConvertAudioSamples(aFrom, aTo, aCount);
1.129 + return;
1.130 + }
1.131 + for (int i = 0; i < aCount; ++i) {
1.132 + aTo[i] = FloatToAudioSample<To>(AudioSampleToFloat(aFrom[i])*aScale);
1.133 + }
1.134 +}
1.135 +inline void
1.136 +ConvertAudioSamplesWithScale(const int16_t* aFrom, int16_t* aTo, int aCount, float aScale)
1.137 +{
1.138 + if (aScale == 1.0f) {
1.139 + ConvertAudioSamples(aFrom, aTo, aCount);
1.140 + return;
1.141 + }
1.142 + if (0.0f <= aScale && aScale < 1.0f) {
1.143 + int32_t scale = int32_t((1 << 16) * aScale);
1.144 + for (int i = 0; i < aCount; ++i) {
1.145 + aTo[i] = int16_t((int32_t(aFrom[i]) * scale) >> 16);
1.146 + }
1.147 + return;
1.148 + }
1.149 + for (int i = 0; i < aCount; ++i) {
1.150 + aTo[i] = FloatToAudioSample<int16_t>(AudioSampleToFloat(aFrom[i])*aScale);
1.151 + }
1.152 +}
1.153 +
1.154 +// In place audio sample scaling.
1.155 +inline void
1.156 +ScaleAudioSamples(float* aBuffer, int aCount, float aScale)
1.157 +{
1.158 + for (int32_t i = 0; i < aCount; ++i) {
1.159 + aBuffer[i] *= aScale;
1.160 + }
1.161 +}
1.162 +
1.163 +inline void
1.164 +ScaleAudioSamples(short* aBuffer, int aCount, float aScale)
1.165 +{
1.166 + int32_t volume = int32_t((1 << 16) * aScale);
1.167 + for (int32_t i = 0; i < aCount; ++i) {
1.168 + aBuffer[i] = short((int32_t(aBuffer[i]) * volume) >> 16);
1.169 + }
1.170 +}
1.171 +
1.172 +inline const void*
1.173 +AddAudioSampleOffset(const void* aBase, AudioSampleFormat aFormat,
1.174 + int32_t aOffset)
1.175 +{
1.176 + static_assert(AUDIO_FORMAT_S16 == 0, "Bad constant");
1.177 + static_assert(AUDIO_FORMAT_FLOAT32 == 1, "Bad constant");
1.178 + NS_ASSERTION(aFormat == AUDIO_FORMAT_S16 || aFormat == AUDIO_FORMAT_FLOAT32,
1.179 + "Unknown format");
1.180 +
1.181 + return static_cast<const uint8_t*>(aBase) + (aFormat + 1)*2*aOffset;
1.182 +}
1.183 +
1.184 +} // namespace mozilla
1.185 +
1.186 +#endif /* MOZILLA_AUDIOSAMPLEFORMAT_H_ */
