Aegisub/aegisub/src/audio_provider_convert.cpp

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// Copyright (c) 2008, Rodrigo Braz Monteiro
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of the Aegisub Group nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// -----------------------------------------------------------------------------
//
// AEGISUB
//
// Website: http://aegisub.cellosoft.com
// Contact: mailto:zeratul@cellosoft.com
//
///////////
// Headers
#include "config.h"
#include "audio_provider_convert.h"
#include "audio_provider_downmix.h"
///////////////
// Constructor
ConvertAudioProvider::ConvertAudioProvider(AudioProvider *src) {
source = src;
channels = source->GetChannels();
num_samples = source->GetNumSamples();
sample_rate = source->GetSampleRate();
bytes_per_sample = 2;
sampleMult = 1;
if (sample_rate < 16000) sampleMult = 4;
else if (sample_rate < 32000) sampleMult = 2;
sample_rate *= sampleMult;
num_samples *= sampleMult;
}
//////////////
// Destructor
ConvertAudioProvider::~ConvertAudioProvider() {
delete source;
}
/////////////////////
// Convert to 16-bit
void ConvertAudioProvider::Make16Bit(const char *src, short *dst, int64_t count) {
for (int64_t i=0;i<count;i++) {
dst[i] = (src[i]-128)*255;
}
}
//////////////////////
// Change sample rate
// This requres 16-bit input
void ConvertAudioProvider::ChangeSampleRate(const short *src, short *dst, int64_t count) {
// Upsample by 2
if (sampleMult == 2) {
int64_t size = count/2;
short cur;
short next = 0;
for (int64_t i=0;i<size;i++) {
cur = next;
next = *src++;
*(dst++) = cur;
*(dst++) = (cur+next)/2;
}
if (count%2) *(dst++) = next;
}
// Upsample by 4
else if (sampleMult == 4) {
int64_t size = count/4;
short cur;
short next = 0;
for (int64_t i=0;i<size;i++) {
cur = next;
next = *(src++);
*(dst++) = cur;
*(dst++) = (cur*3+next)/4;
*(dst++) = (cur+next)/2;
*(dst++) = (cur+next*3)/4;
}
for (int i=0;i<count%4;i++) *(dst++) = next;
}
// Nothing to do (shouldn't really get here, but...)
else if (sampleMult == 1) memcpy((void*)src,dst,count);
}
/////////////
// Get audio
void ConvertAudioProvider::GetAudio(void *destination, int64_t start, int64_t count) {
// Bits per sample
int srcBps = source->GetBytesPerSample();
// Nothing to do
if (sampleMult == 1 && srcBps == 2) {
source->GetAudio(destination,start,count);
}
// Convert
else {
// Allocate buffers with sufficient size for the entire operation
size_t fullSize = count;
int64_t srcCount = count / sampleMult;
short *buffer1 = NULL;
short *buffer2 = NULL;
short *last = NULL;
// Read audio
buffer1 = new short[fullSize];
source->GetAudio(buffer1,start/sampleMult,srcCount);
// Convert from 8-bit to 16-bit
if (srcBps == 1) {
if (sampleMult == 1) {
Make16Bit((const char*)buffer1,(short*)destination,srcCount);
}
else {
buffer2 = new short[fullSize];
Make16Bit((const char*)buffer1,buffer2,srcCount);
last = buffer2;
}
}
// Already 16-bit
else if (srcBps == 2) last = buffer1;
// Convert sample rate
if (sampleMult != 1) {
ChangeSampleRate(last,(short*)destination,count);
}
delete [] buffer1;
delete [] buffer2;
}
}
// See if we need to downmix the number of channels
AudioProvider *CreateConvertAudioProvider(AudioProvider *source_provider) {
AudioProvider *provider = source_provider;
if (provider->GetBytesPerSample() != 2 || provider->GetSampleRate() < 32000)
provider = new ConvertAudioProvider(source_provider);
if (provider->GetChannels() != 1)
provider = new DownmixingAudioProvider(provider);
return provider;
}