从mp3文件中快速提取CMSampleBuffer

Question

我正在尝试从mp3文件中提取CMSampleBuffer，以将其用于录制视频。这是代码：

首先从mp3获取PCM缓冲区

guard let audioPCMBuffer = AVAudioPCMBuffer(pcmFormat: audioFile.processingFormat,
                                              frameCapacity: 1) else {
                                                cancel()
                                                return
  }
try audioFile.read(into: audioPCMBuffer, frameCount: 1)
if let audioSampleBuffer = this.processAudioData(audioData: audioPCMBuffer.audioBufferList, audioFormat: audioDataFormat.formatDescription, timingInfo: timingInfo, framesNumber: audioPCMBuffer.frameLength, mono: audioPCMBuffer.audioBufferList.pointee.mNumberBuffers == 1) {
      this.videoWriterInput?.append(buffer)
      this.audioWriterInput?.append(audioSampleBuffer)
    } else {
      // show error?
    }

代码如何将pcm缓冲区转换为cmsamplebuffer：

var sbuf : CMSampleBuffer?
var status : OSStatus?
var format: CMFormatDescription?

let audioFormat = CMAudioFormatDescriptionGetStreamBasicDescription(inputFormat)
var timing = timingInfo

var acl = AudioChannelLayout();
bzero(&acl, MemoryLayout<AudioChannelLayout>.size);
acl.mChannelLayoutTag = mono ? kAudioChannelLayoutTag_Mono : kAudioChannelLayoutTag_Stereo;

status = CMAudioFormatDescriptionCreate(allocator: kCFAllocatorDefault, asbd: audioFormat!, layoutSize: MemoryLayout<AudioChannelLayout>.size, layout: &acl, magicCookieSize: 0, magicCookie: nil, extensions: nil, formatDescriptionOut: &format)
if status != noErr {
  print("Error CMAudioFormatDescriptionCreater :\(String(describing: status?.description))")
  return nil
}

status = CMSampleBufferCreate(allocator: kCFAllocatorDefault, dataBuffer: nil, dataReady: false, makeDataReadyCallback: nil, refcon: nil, formatDescription: format, sampleCount: CMItemCount(framesNumber), sampleTimingEntryCount: 1, sampleTimingArray: &timing, sampleSizeEntryCount: 0, sampleSizeArray: nil, sampleBufferOut: &sbuf)
if status != noErr {
  print("Error CMSampleBufferCreate :\(String(describing: status?.description))")
  return nil
}

guard let buf = sbuf else { return nil}
status = CMSampleBufferSetDataBufferFromAudioBufferList(buf, blockBufferAllocator: kCFAllocatorDefault, blockBufferMemoryAllocator: kCFAllocatorDefault, flags: 0, bufferList: audioData)
let audiobufferListRaw: AudioBufferList = audioData.pointee
if status != noErr {
  print("Error cCMSampleBufferSetDataBufferFromAudioBufferList :\(String(describing: status?.description))")
  return nil
}

return buf

但是我总是收到错误代码：-12771: kCMSimpleQueueError_RequiredParameterMissing。这是我的音频格式和示例缓冲区的日志：

(lldb) po self.audioFile!.processingFormat
<AVAudioFormat 0x1c4286090:  1 ch,  44100 Hz, Float32>

(lldb) po audiobufferListRaw
▿ AudioBufferList
  - mNumberBuffers : 1
  ▿ mBuffers : AudioBuffer
    - mNumberChannels : 1
    - mDataByteSize : 4
    ▿ mData : Optional<UnsafeMutableRawPointer>
      ▿ some : 0x00000001c402c5e0
        - pointerValue : 7583483360

(lldb) po buf
CMSampleBuffer 0x141d1b6a0 retainCount: 9 allocator: 0x1b5f76240
    invalid = NO
    dataReady = NO
    makeDataReadyCallback = 0x0
    makeDataReadyRefcon = 0x0
    formatDescription = <CMAudioFormatDescription 0x1c4114e20 [0x1b5f76240]> {
    mediaType:'soun' 
    mediaSubType:'lpcm' 
    mediaSpecific: {
        ASBD: {
            mSampleRate: 44100.000000 
            mFormatID: 'lpcm' 
            mFormatFlags: 0x29 
            mBytesPerPacket: 4 
            mFramesPerPacket: 1 
            mBytesPerFrame: 4 
            mChannelsPerFrame: 1 
            mBitsPerChannel: 32     } 
        cookie: {(null)} 
        ACL: {Mono}
        FormatList Array: {(null)} 
    } 
    extensions: {(null)}
}
    sbufToTrackReadiness = 0x0
    numSamples = 1
    sampleTimingArray[1] = {
        {PTS = {253696201314000/1000000000 = 253696.201}, DTS = {INVALID}, duration = {INVALID}},
    }
    dataBuffer = 0x0

任何想法，为什么CMSampleBufferSetDataBufferFromAudioBufferList总是返回错误