gecko-dev/content/media/AudioSegment.cpp

194 строки
6.3 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
#include "AudioSegment.h"
namespace mozilla {
static PRUint16
FlipByteOrderIfBigEndian(PRUint16 aValue)
{
PRUint16 s = aValue;
#if defined(IS_BIG_ENDIAN)
s = (s << 8) | (s >> 8);
#endif
return s;
}
/*
* 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
*/
static float
SampleToFloat(float aValue)
{
return aValue;
}
static float
SampleToFloat(PRUint8 aValue)
{
return (aValue - 128)/128.0f;
}
static float
SampleToFloat(PRInt16 aValue)
{
return PRInt16(FlipByteOrderIfBigEndian(aValue))/32768.0f;
}
static void
FloatToSample(float aValue, float* aOut)
{
*aOut = aValue;
}
static void
FloatToSample(float aValue, PRUint8* aOut)
{
float v = aValue*128 + 128;
float clamped = NS_MAX(0.0f, NS_MIN(255.0f, v));
*aOut = PRUint8(clamped);
}
static void
FloatToSample(float aValue, PRInt16* aOut)
{
float v = aValue*32768.0f;
float clamped = NS_MAX(-32768.0f, NS_MIN(32767.0f, v));
*aOut = PRInt16(FlipByteOrderIfBigEndian(PRInt16(clamped)));
}
template <class SrcT, class DestT>
static void
InterleaveAndConvertBuffer(const SrcT* aSource, PRInt32 aSourceLength,
PRInt32 aLength,
float aVolume,
PRInt32 aChannels,
DestT* aOutput)
{
DestT* output = aOutput;
for (PRInt32 i = 0; i < aLength; ++i) {
for (PRInt32 channel = 0; channel < aChannels; ++channel) {
float v = SampleToFloat(aSource[channel*aSourceLength + i])*aVolume;
FloatToSample(v, output);
++output;
}
}
}
static void
InterleaveAndConvertBuffer(const PRInt16* aSource, PRInt32 aSourceLength,
PRInt32 aLength,
float aVolume,
PRInt32 aChannels,
PRInt16* aOutput)
{
PRInt16* output = aOutput;
float v = NS_MAX(NS_MIN(aVolume, 1.0f), -1.0f);
PRInt32 volume = PRInt32((1 << 16) * v);
for (PRInt32 i = 0; i < aLength; ++i) {
for (PRInt32 channel = 0; channel < aChannels; ++channel) {
PRInt16 s = FlipByteOrderIfBigEndian(aSource[channel*aSourceLength + i]);
*output = FlipByteOrderIfBigEndian(PRInt16((PRInt32(s) * volume) >> 16));
++output;
}
}
}
template <class SrcT>
static void
InterleaveAndConvertBuffer(const SrcT* aSource, PRInt32 aSourceLength,
PRInt32 aLength,
float aVolume,
PRInt32 aChannels,
void* aOutput, nsAudioStream::SampleFormat aOutputFormat)
{
switch (aOutputFormat) {
case nsAudioStream::FORMAT_FLOAT32:
InterleaveAndConvertBuffer(aSource, aSourceLength, aLength, aVolume,
aChannels, static_cast<float*>(aOutput));
break;
case nsAudioStream::FORMAT_S16_LE:
InterleaveAndConvertBuffer(aSource, aSourceLength, aLength, aVolume,
aChannels, static_cast<PRInt16*>(aOutput));
break;
case nsAudioStream::FORMAT_U8:
InterleaveAndConvertBuffer(aSource, aSourceLength, aLength, aVolume,
aChannels, static_cast<PRUint8*>(aOutput));
break;
}
}
static void
InterleaveAndConvertBuffer(const void* aSource, nsAudioStream::SampleFormat aSourceFormat,
PRInt32 aSourceLength,
PRInt32 aOffset, PRInt32 aLength,
float aVolume,
PRInt32 aChannels,
void* aOutput, nsAudioStream::SampleFormat aOutputFormat)
{
switch (aSourceFormat) {
case nsAudioStream::FORMAT_FLOAT32:
InterleaveAndConvertBuffer(static_cast<const float*>(aSource) + aOffset, aSourceLength,
aLength,
aVolume,
aChannels,
aOutput, aOutputFormat);
break;
case nsAudioStream::FORMAT_S16_LE:
InterleaveAndConvertBuffer(static_cast<const PRInt16*>(aSource) + aOffset, aSourceLength,
aLength,
aVolume,
aChannels,
aOutput, aOutputFormat);
break;
case nsAudioStream::FORMAT_U8:
InterleaveAndConvertBuffer(static_cast<const PRUint8*>(aSource) + aOffset, aSourceLength,
aLength,
aVolume,
aChannels,
aOutput, aOutputFormat);
break;
}
}
void
AudioSegment::ApplyVolume(float aVolume)
{
for (ChunkIterator ci(*this); !ci.IsEnded(); ci.Next()) {
ci->mVolume *= aVolume;
}
}
static const int STATIC_AUDIO_BUFFER_BYTES = 50000;
void
AudioSegment::WriteTo(nsAudioStream* aOutput)
{
NS_ASSERTION(mChannels == aOutput->GetChannels(), "Wrong number of channels");
nsAutoTArray<PRUint8,STATIC_AUDIO_BUFFER_BYTES> buf;
PRUint32 frameSize = GetSampleSize(aOutput->GetFormat())*mChannels;
for (ChunkIterator ci(*this); !ci.IsEnded(); ci.Next()) {
AudioChunk& c = *ci;
if (frameSize*c.mDuration > PR_UINT32_MAX) {
NS_ERROR("Buffer overflow");
return;
}
buf.SetLength(PRInt32(frameSize*c.mDuration));
if (c.mBuffer) {
InterleaveAndConvertBuffer(c.mBuffer->Data(), c.mBufferFormat, c.mBufferLength,
c.mOffset, PRInt32(c.mDuration),
c.mVolume,
aOutput->GetChannels(),
buf.Elements(), aOutput->GetFormat());
} else {
// Assumes that a bit pattern of zeroes == 0.0f
memset(buf.Elements(), 0, buf.Length());
}
aOutput->Write(buf.Elements(), PRInt32(c.mDuration));
}
}
}