UseExtAF.cpp
/* |
Copyright (C) 2016 Apple Inc. All Rights Reserved. |
See LICENSE.txt for this sample’s licensing information |
Abstract: |
Extended Audio File Converter Sample |
*/ |
/* |
This is a simple example program that shows the usage of the ExtendedAudioFile API found in AudioToolbox.framework |
Its input is an audio file containing linear pcm audio, and it generates a specified compressed audio file |
*/ |
#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__) |
#include <AudioToolbox/AudioToolbox.h> |
#else |
#include "AudioToolbox.h" |
#include "ExtendedAudioFile.h" |
#endif |
#include "CAStreamBasicDescription.h" |
#include "CAXException.h" |
const UInt32 kSrcBufSize = 32768; |
int ConvertFile (CFURLRef inputFileURL, |
CAStreamBasicDescription &inputFormat, |
CFURLRef outputFileURL, |
AudioFileTypeID outputFileType, |
CAStreamBasicDescription &outputFormat, |
UInt32 outputBitRate) |
{ |
ExtAudioFileRef infile, outfile; |
// first open the input file |
OSStatus err = ExtAudioFileOpenURL (inputFileURL, &infile); |
XThrowIfError (err, "ExtAudioFileOpen"); |
// if outputBitRate is specified, this can change the sample rate of the output file |
// so we let this "take care of itself" |
if (outputBitRate) |
outputFormat.mSampleRate = 0.; |
// create the output file (this will erase an exsiting file) |
err = ExtAudioFileCreateWithURL (outputFileURL, outputFileType, &outputFormat, NULL, kAudioFileFlags_EraseFile, &outfile); |
XThrowIfError (err, "ExtAudioFileCreateNew"); |
// get and set the client format - it should be lpcm |
CAStreamBasicDescription clientFormat = (inputFormat.mFormatID == kAudioFormatLinearPCM ? inputFormat : outputFormat); |
UInt32 size = sizeof(clientFormat); |
err = ExtAudioFileSetProperty(infile, kExtAudioFileProperty_ClientDataFormat, size, &clientFormat); |
XThrowIfError (err, "ExtAudioFileSetProperty inFile, kExtAudioFileProperty_ClientDataFormat"); |
size = sizeof(clientFormat); |
err = ExtAudioFileSetProperty(outfile, kExtAudioFileProperty_ClientDataFormat, size, &clientFormat); |
XThrowIfError (err, "ExtAudioFileSetProperty outFile, kExtAudioFileProperty_ClientDataFormat"); |
if( outputBitRate > 0 ) { |
printf ("Dest bit rate: %d\n", (int)outputBitRate); |
AudioConverterRef outConverter; |
size = sizeof(outConverter); |
err = ExtAudioFileGetProperty(outfile, kExtAudioFileProperty_AudioConverter, &size, &outConverter); |
XThrowIfError (err, "ExtAudioFileGetProperty outFile, kExtAudioFileProperty_AudioConverter"); |
err = AudioConverterSetProperty(outConverter, kAudioConverterEncodeBitRate, |
sizeof(outputBitRate), &outputBitRate); |
XThrowIfError (err, "AudioConverterSetProperty, kAudioConverterEncodeBitRate"); |
// we have changed the converter, so we should do this in case |
// setting a converter property changes the converter used by ExtAF in some manner |
CFArrayRef config = NULL; |
err = ExtAudioFileSetProperty(outfile, kExtAudioFileProperty_ConverterConfig, sizeof(config), &config); |
XThrowIfError (err, "ExtAudioFileSetProperty outFile, kExtAudioFileProperty_ConverterConfig"); |
} |
// set up buffers |
char srcBuffer[kSrcBufSize]; |
// do the read and write - the conversion is done on and by the write call |
while (1) |
{ |
AudioBufferList fillBufList; |
fillBufList.mNumberBuffers = 1; |
fillBufList.mBuffers[0].mNumberChannels = inputFormat.mChannelsPerFrame; |
fillBufList.mBuffers[0].mDataByteSize = kSrcBufSize; |
fillBufList.mBuffers[0].mData = srcBuffer; |
// client format is always linear PCM - so here we determine how many frames of lpcm |
// we can read/write given our buffer size |
UInt32 numFrames = (kSrcBufSize / clientFormat.mBytesPerFrame); |
// printf("test %d\n", numFrames); |
err = ExtAudioFileRead (infile, &numFrames, &fillBufList); |
XThrowIfError (err, "ExtAudioFileRead"); |
if (!numFrames) { |
// this is our termination condition |
break; |
} |
err = ExtAudioFileWrite(outfile, numFrames, &fillBufList); |
XThrowIfError (err, "ExtAudioFileWrite"); |
} |
// close |
ExtAudioFileDispose(outfile); |
ExtAudioFileDispose(infile); |
return 0; |
} |
Copyright © 2016 Apple Inc. All Rights Reserved. Terms of Use | Privacy Policy | Updated: 2016-09-29