我正在尝试将.m4a格式的给定音频文件转换为.aiff格式,使用
this post的答案.我已将代码转换为Swift 3.0.
func convertAudio(_ url: URL,outputURL: URL) {
var error : Osstatus = noErr
var destinationFile : ExtAudioFileRef? = nil
var sourceFile : ExtAudioFileRef? = nil
var srcFormat : AudioStreamBasicDescription = AudioStreamBasicDescription()
var dstFormat : AudioStreamBasicDescription = AudioStreamBasicDescription()
var audioConverter : AudioConverterRef? = nil
ExtAudioFileOpenURL(url as CFURL,&sourceFile)
var thePropertySize: UInt32 = UInt32(MemoryLayout.stride(ofValue: srcFormat))
ExtAudioFileGetProperty(sourceFile!,kExtAudioFileProperty_FileDataFormat,&thePropertySize,&srcFormat)
dstFormat.mSampleRate = 44100 //Set sample rate
dstFormat.mFormatID = kAudioFormatLinearPCM
dstFormat.mChannelsPerFrame = 1
dstFormat.mBitsPerChannel = 16
dstFormat.mBytesPerPacket = 2 * dstFormat.mChannelsPerFrame
dstFormat.mBytesPerFrame = 2 * dstFormat.mChannelsPerFrame
dstFormat.mFramesPerPacket = 1
dstFormat.mFormatFlags = kAudioFormatFlagIsBigEndian | kAudioFormatFlagIsSignedInteger
//Create destination file
ExtAudioFileCreateWithURL(outputURL as CFURL,kAudioFileaifFType,&dstFormat,nil,AudioFileFlags.eraseFile.rawValue,&destinationFile)
ExtAudioFileSetProperty(sourceFile!,kExtAudioFileProperty_ClientDataFormat,thePropertySize,&dstFormat)
ExtAudioFileSetProperty(destinationFile!,&dstFormat)
var size : UInt32 = UInt32(MemoryLayout.stride(ofValue: audioConverter))
ExtAudioFileGetProperty(destinationFile!,kExtAudioFileProperty_AudioConverter,&size,&audioConverter)
var canResume : UInt32 = 0
size = UInt32(MemoryLayout.stride(ofValue: canResume))
error = AudioConverterGetProperty(audioConverter!,kAudioConverterPropertyCanResumeFromInterruption,&canResume)
let bufferByteSize : UInt32 = 32768
var srcBuffer = [UInt8](repeating: 0,count: 32768)
var sourceFrameOffset : ULONG = 0
print("Converting audio file")
while(true){
var fillBufList = audiobufferlist(
mNumberBuffers: 1,mBuffers: AudioBuffer(
mNumberChannels: 2,mDataByteSize: UInt32(srcBuffer.count),mData: &srcBuffer
)
)
var numFrames : UInt32 = 0
if(dstFormat.mBytesPerFrame > 0){
numFrames = bufferByteSize / dstFormat.mBytesPerFrame
}
ExtAudioFileRead(sourceFile!,&numFrames,&fillBufList)
if(numFrames == 0){
error = noErr;
break;
}
sourceFrameOffset += numFrames
error = ExtAudioFileWrite(destinationFile!,numFrames,&fillBufList)
}
ExtAudioFiledispose(destinationFile!)
ExtAudioFiledispose(sourceFile!)
}
问题是audioConverter似乎在这一行是零
error = AudioConverterGetProperty(audioConverter!,&canResume)
而我似乎无法弄清楚为什么.我错过了什么？
跳过AudioConverterGetProperty
你实际上没有使用它.
以下代码片段将音频文件转换为aifF：它以一种支持的格式读取sourceFile,创建aifF编码器,并使用bufferByteSize缓冲区循环它.错误处理得当.
完整代码,swift 3：
func convertAudio(_ url: URL,outputURL: URL) {
var error : Osstatus = noErr
var destinationFile : ExtAudioFileRef? = nil
var sourceFile : ExtAudioFileRef? = nil
var srcFormat : AudioStreamBasicDescription = AudioStreamBasicDescription()
var dstFormat : AudioStreamBasicDescription = AudioStreamBasicDescription()
ExtAudioFileOpenURL(url as CFURL,&srcFormat)
dstFormat.mSampleRate = 44100 //Set sample rate
dstFormat.mFormatID = kAudioFormatLinearPCM
dstFormat.mChannelsPerFrame = 1
dstFormat.mBitsPerChannel = 16
dstFormat.mBytesPerPacket = 2 * dstFormat.mChannelsPerFrame
dstFormat.mBytesPerFrame = 2 * dstFormat.mChannelsPerFrame
dstFormat.mFramesPerPacket = 1
dstFormat.mFormatFlags = kAudioFormatFlagIsBigEndian |
kAudioFormatFlagIsSignedInteger
// Create destination file
error = ExtAudioFileCreateWithURL(
outputURL as CFURL,&destinationFile)
reportError(error: error)
error = ExtAudioFileSetProperty(sourceFile!,&dstFormat)
reportError(error: error)
error = ExtAudioFileSetProperty(destinationFile!,&dstFormat)
reportError(error: error)
let bufferByteSize : UInt32 = 32768
var srcBuffer = [UInt8](repeating: 0,count: 32768)
var sourceFrameOffset : ULONG = 0
while(true){
var fillBufList = audiobufferlist(
mNumberBuffers: 1,mData: &srcBuffer
)
)
var numFrames : UInt32 = 0
if(dstFormat.mBytesPerFrame > 0){
numFrames = bufferByteSize / dstFormat.mBytesPerFrame
}
error = ExtAudioFileRead(sourceFile!,&fillBufList)
reportError(error: error)
if(numFrames == 0){
error = noErr;
break;
}
sourceFrameOffset += numFrames
error = ExtAudioFileWrite(destinationFile!,&fillBufList)
reportError(error: error)
}
error = ExtAudioFiledispose(destinationFile!)
reportError(error: error)
error = ExtAudioFiledispose(sourceFile!)
reportError(error: error)
}
支持方式：
func reportError(error: Osstatus) {
// Handle error
}
调用：
let sourceUrl = URL(string: Bundle.main.path(forResource: "sample",ofType: "mp3")!)
let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory,.userDomainMask,true)
let documentsDirectory = URL(string: paths.first!)
let destUrl = documentsDirectory?.appendingPathComponent("converted.aiff")
if let sourceUrl = sourceUrl,let destUrl = destUrl {
print("from \(sourceUrl.absoluteString) to \(destUrl.absoluteString)")
convertAudio(sourceUrl,outputURL: destUrl)
}