swift - AVAudioFile `framePosition` を設定するとクラッシュする

Question

framePositionAVAudioFile の を現在の framePosition 以外に設定すると、クラッシュが発生します。

エラー - 6658

Apple Docsで調べたものは次のとおりです。

kExtAudioFileError_InvalidSeek: 書き込みの試み、またはオフセットが範囲外です。

framePosition設定しようとしている位置が AVAudioFile の よりも小さく、 0 を超えていることを確認できるので、これは私にとって奇妙ですlength。

コード：

  // Start Recording to file
  func startRecording(atTimeInFile: TimeInterval) throws {
    let tapNode: AVAudioNode = mixerNode
    let format = tapNode.outputFormat(forBus: 0)
    let semaphore = DispatchSemaphore(value: 0)
    
    duration = 0
    startTime = atTimeInFile
    
    // Check to see if recording file already has content
    
    let f: AVAudioFile? = {
      if FileManager.default.fileExists(atPath: FileManagerHelper.recordingLocalURL().relativePath) {
        return try? AVAudioFile(forReading: FileManagerHelper.recordingLocalURL())
      } else {
        return nil
      }
    }()
    
    if let f = f {
      // The file we opened for writing already has data written to it
      // Let's load the buffer data in from that the file
      guard let bufferData = AVAudioPCMBuffer(pcmFormat: f.processingFormat, frameCapacity: AVAudioFrameCount(f.length)) else {
        throw NSError(domain: "Failed to load the content of the existing file.", code: -10, userInfo: nil)
      }
      
      bufferData.frameLength = bufferData.frameCapacity
      
      do {
        try f.read(into: bufferData)
      } catch {
        throw NSError(domain: "Failed to read from the content of the existing file.", code: -20, userInfo: nil)
      }
      
      // AVAudioFile uses the Core Audio Format (CAF) to write to disk.
      // So we're using the caf file extension.
      file = try AVAudioFile(forWriting: FileManagerHelper.recordingLocalURL(), settings: format.settings)
      
      do {
        file!.framePosition = 0
        try self.file!.write(from: bufferData)
      } catch {
        throw NSError(domain: "Failed to write from the content of the existing file.", code: -30, userInfo: nil)
      }
    }
    
    else {
      file = try AVAudioFile(forWriting: FileManagerHelper.recordingLocalURL(), settings: format.settings)
    }

    if file!.duration == 0 {
      file!.framePosition = AVAudioFramePosition(0)
    } else {
      let percentThrough = CGFloat(atTimeInFile) / CGFloat(file!.duration)
      let pos = AVAudioFramePosition(percentThrough * CGFloat(file!.length))
      
      file!.framePosition = pos // CRASH OCCURS HERE
    }
    
    tapNode.installTap(onBus: 0, bufferSize: bufferSize, format: format, block: {
      (buffer, _) in
      do {
        buffer.frameLength = 1024 // Tap is now called every 40ms. By default, tap is called every 0.375s
        try self.file!.write(from: buffer)
        self.delegate?.recorderDidRecieveAudioBuffer(self, buffer: buffer)
        semaphore.signal()
      } catch {
        log("Error writing mic data to file.", msgType: .error)
      }
    })

    try engine.start()

    semaphore.wait()
    state = .recording
    startObservingTime()
  }

これは、クラッシュの完全な説明です。

    ExtAudioFile.cpp:1084:Seek: about to throw -66568: seek to frame in audio file
2020-11-09 18:01:46.032612-0800 Application[15316:800908] [avae]            AVAEInternal.h:109   [AVAudioFile.mm:515:-[AVAudioFile setFramePosition:]: (ExtAudioFileSeek(_imp->_extAudioFile, pos)): error -66568
2020-11-09 18:01:46.034491-0800 Application[15316:800908] *** Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'error -66568'
*** First throw call stack:
(0x187b1c878 0x19c072c50 0x187a22000 0x197aa3e48 0x197b4270c 0x1004fc164 0x10048b43c 0x10048b198 0x10048b254 0x18a010e54 0x18a01a7b8 0x18a0173f4 0x18a01696c 0x18a00aa98 0x18a009e44 0x18a5111b4 0x18a4ea4ec 0x18a574488 0x18a577440 0x18a56e8ec 0x187a9876c 0x187a98668 0x187a97960 0x187a91a8c 0x187a9121c 0x19eb10784 0x18a4ca200 0x18a4cfa74 0x10048f270 0x1877516c0)
libc++abi.dylib: terminating with uncaught exception of type NSException
*** Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'error -66568'
terminating with uncaught exception of type NSException

---

更新 1 : 読み取り用に開かれた AVAudioFile の framePosition を設定できることに気付きましたが、同じ URL で書き込み用に開かれた AVAudioFilefのフレーム位置を設定できません。file

更新 2 : ファイルを別の URL に書き込もうとしました。

file = try AVAudioFile(forWriting: FileManagerHelper.recordingLocalURL(), settings: format.settings)

と

file = try AVAudioFile(forWriting: FileManagerHelper.recordingLocalURL2(), settings: format.settings)

if let f = fブロックで。

ただし、名声の位置を設定すると、範囲外のエラーが発生します。