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audio.cpp
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audio.cpp
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#include <string.h>
#include "audio.h"
#include "../debug.h"
namespace Util{
AudioConverter::AudioConverter(Encoding inputEncoding, int inputChannels, int inputFrequency,
Encoding outputEncoding, int outputChannels, int outputFrequency):
buffer(NULL),
bufferSize(0){
input.bytes = inputEncoding;
input.channels = inputChannels;
input.frequency = inputFrequency;
output.bytes = outputEncoding;
output.channels = outputChannels;
output.frequency = outputFrequency;
sizeRatio = (double) byteSize(output) * output.frequency / ((double) byteSize(input) * input.frequency);
}
int AudioConverter::byteSize(const Format & what){
return encodingBytes(what.bytes) * what.channels;
}
/* how many bytes an encoding takes up */
int AudioConverter::encodingBytes(Encoding what){
switch (what){
case Unsigned8: return 1;
case Signed16: return 2;
case Unsigned16: return 2;
case Float32: return 4;
}
return 1;
}
unsigned int AudioConverter::convertedLength(int length){
// return length * sizeRatio;
int total = length * sizeRatio;
/* make sure we get an even number of samples */
if (total % byteSize(output) != 0){
total -= total % byteSize(output);
}
return total;
}
double CubicInterpolate(double y0, double y1,
double y2, double y3,
double mu){
double a0,a1,a2,a3,mu2;
mu2 = mu*mu;
a0 = y3 - y2 - y0 + y1;
a1 = y0 - y1 - a0;
a2 = y2 - y0;
a3 = y1;
return (a0*mu*mu2+a1*mu2+a2*mu+a3);
}
template <class Input, class Output>
Output clamp(double input){
Output top = (1 << (sizeof(Output) * 8 - 1)) - 1;
Output bottom = -(1 << (sizeof(Output) * 8 - 1));
if (input > top){
return top;
}
if (input < bottom){
return bottom;
}
return input;
}
template <>
signed short clamp<unsigned char>(double input){
return ((input - 127) / 255) * (1 << (sizeof(signed short) * 8 - 1));
}
template <>
unsigned char clamp<unsigned char>(double input){
if (input > 255){
input = 255;
}
if (input < 0){
input = 0;
}
return input;
}
template <>
float clamp<float>(double input){
if (input > 1){
input = 1;
}
if (input < -1){
input = -1;
}
return input;
}
template <>
unsigned short clamp<signed short>(double input){
return (int) clamp<signed short, signed short>(input) + (int) (1 << (sizeof(signed short) * 8 - 1));
}
template <>
float clamp<short unsigned int>(double input){
double out = input / (1 << (sizeof(unsigned short) * 8));
if (out > 1){
return 1;
}
if (out < -1){
return -1;
}
return out;
}
template <>
float clamp<unsigned char>(double input){
double out = input / (1 << (sizeof(unsigned char) * 8));
if (out > 1){
return 1;
}
if (out < -1){
return -1;
}
return out;
}
template <>
unsigned char clamp<signed short>(double input){
double out = input / (1 << (sizeof(signed short) * 8 - 1));
if (out > 1){
return 1;
}
if (out < -1){
return -1;
}
/* -1,1 -> 0,255 */
return (unsigned char)((out + 1) * 128);
}
template <>
float clamp<signed short>(double input){
double out = input / (1 << (sizeof(signed short) * 8 - 1));
if (out > 1){
return 1;
}
if (out < -1){
return -1;
}
return out;
}
template <class SizeInput, class SizeOutput>
void doConvertRate(SizeInput * input, int inputSamples, int inputChannels, SizeOutput * buffer, int outputSamples, int outputChannels, double ratio){
for (int sample = 0; sample < outputSamples; sample += 1){
double inputSample = sample / ratio;
for (int channel = 0; channel < outputChannels; channel += 1){
int inputChannel = inputChannels > channel ? channel : inputChannels - 1;
int sample0 = ((int) inputSample - 1) * inputChannels + inputChannel;
int sample1 = ((int) inputSample + 0) * inputChannels + inputChannel;
int sample2 = ((int) inputSample + 1) * inputChannels + inputChannel;
int sample3 = ((int) inputSample + 2) * inputChannels + inputChannel;
if (sample0 < 0){
sample0 = sample1;
}
if (sample2 >= inputSamples * inputChannels){
sample2 = sample1;
}
if (sample3 >= inputSamples * inputChannels){
sample3 = sample2;
}
buffer[sample * outputChannels + channel] = clamp<SizeInput, SizeOutput>(CubicInterpolate(input[sample0], input[sample1], input[sample2], input[sample3], inputSample - (int) inputSample));
// Global::debug(0) << "Input[" << sample << "] " << channel << ": " << input[sample1] << " Output: " << buffer[sample * 2 + channel] << std::endl;
}
}
}
template <class Input, class Output>
void doConvert3(void * input, int inputLength, int inputChannels,
void * output, int outputLength, int outputChannels,
double ratio){
doConvertRate<Input, Output>((Input*) input, inputLength / sizeof(Input) / inputChannels, inputChannels,
(Output*) output, outputLength / sizeof(Output) / outputChannels, outputChannels,
ratio);
}
template <class Input>
void doConvert2(void * input, int inputLength, int inputChannels,
Encoding outputType, void * output, int outputLength, int outputChannels,
double ratio){
switch (outputType){
case Unsigned8: doConvert3<Input, unsigned char>(input, inputLength, inputChannels, output, outputLength, outputChannels, ratio); break;
case Signed16: doConvert3<Input, signed short>(input, inputLength, inputChannels, output, outputLength, outputChannels, ratio); break;
case Unsigned16: doConvert3<Input, unsigned short>(input, inputLength, inputChannels, output, outputLength, outputChannels, ratio); break;
case Float32: doConvert3<Input, float>(input, inputLength, inputChannels, output, outputLength, outputChannels, ratio); break;
}
}
void doConvert1(Encoding inputType, void * input, int inputLength, int inputChannels,
Encoding outputType, void * output, int outputLength, int outputChannels, double ratio){
switch (inputType){
case Unsigned8: doConvert2<unsigned char>(input, inputLength, inputChannels, outputType, output, outputLength, outputChannels, ratio); break;
case Signed16: doConvert2<signed short>(input, inputLength, inputChannels, outputType, output, outputLength, outputChannels, ratio); break;
case Unsigned16: doConvert2<unsigned short>(input, inputLength, inputChannels, outputType, output, outputLength, outputChannels, ratio); break;
case Float32: doConvert2<float>(input, inputLength, inputChannels, outputType, output, outputLength, outputChannels, ratio); break;
}
}
int AudioConverter::convert(void * input, int length){
/* no conversion needed */
if (this->input == this->output){
return length;
}
int total = convertedLength(length);
/*
if (total % byteSize(output) != 0){
total -= total % byteSize(output);
}
*/
/* cache the buffer for future use */
if (total > bufferSize){
delete[] buffer;
bufferSize = total;
buffer = new char[bufferSize];
}
double frequencyRatio = (double) output.frequency / (double) this->input.frequency;
doConvert1(this->input.bytes, input, length, this->input.channels, output.bytes, buffer, total, output.channels, frequencyRatio);
memcpy(input, buffer, total);
return total;
}
AudioConverter::~AudioConverter(){
delete[] buffer;
}
bool AudioConverter::Format::operator==(const AudioConverter::Format & him) const {
return this->bytes == him.bytes &&
this->channels == him.channels &&
this->frequency == him.frequency;
}
}

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