play - Conversión de archivo.m4a a.aiff utilizando AudioConverter Swift

avfoundation swift 4

Question

Estoy tratando de convertir un archivo de audio dado en formato .m4a a formato .aiff, usando la respuesta de esta publicación . He convertido el código a 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!, kExtAudioFileProperty_ClientDataFormat, thePropertySize, &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, &size, &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!)
}

El problema es audioConverter parece ser nulo en esta línea

error = AudioConverterGetProperty(audioConverter!, kAudioConverterPropertyCanResumeFromInterruption, &size, &canResume)

Y no puedo entender por qué. ¿Qué me perdí?

Answer 1

Omita AudioConverterGetProperty

En realidad no lo estás usando.
El siguiente fragmento convertirá un archivo de audio a AIFF: lee el archivo de origen en uno de los formatos compatibles, crea un codificador AIFF y lo recorre utilizando un buffer bufferByteSize . Los errores son levemente manejados.

Código completo, 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, &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
error = ExtAudioFileCreateWithURL(
outputURL as CFURL,
kAudioFileAIFFType,
&dstFormat,
nil,
AudioFileFlags.eraseFile.rawValue,
&destinationFile)
reportError(error: error)
error = ExtAudioFileSetProperty(sourceFile!,
kExtAudioFileProperty_ClientDataFormat,
thePropertySize,
&dstFormat)
reportError(error: error)
error = ExtAudioFileSetProperty(destinationFile!,
kExtAudioFileProperty_ClientDataFormat,
thePropertySize,
&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,
mBuffers: AudioBuffer(
mNumberChannels: 2,
mDataByteSize: UInt32(srcBuffer.count),
mData: &srcBuffer
)
)
var numFrames : UInt32 = 0
if(dstFormat.mBytesPerFrame > 0){
numFrames = bufferByteSize / dstFormat.mBytesPerFrame
}
error = ExtAudioFileRead(sourceFile!, &numFrames, &fillBufList)
reportError(error: error)
if(numFrames == 0){
error = noErr;
break;
}
sourceFrameOffset += numFrames
error = ExtAudioFileWrite(destinationFile!, numFrames, &fillBufList)
reportError(error: error)
}
error = ExtAudioFileDispose(destinationFile!)
reportError(error: error)
error = ExtAudioFileDispose(sourceFile!)
reportError(error: error)
}

Método de apoyo:

func reportError(error: OSStatus) {
// Handle error
}

Invocación:

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)
}