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我想在 iOS 上实时录制音频，分析原始音频数据并保存部分录制的数据。我正在使用以下代码记录数据：https ://gist.github.com/hotpaw2/ba815fc23b5d642705f2b1dedfaf0107

现在，我的数据保存在浮点数组中，我想将其保存到音频文件中。我试着用这段代码来做：

let fileMgr = FileManager.default
    let dirPaths = fileMgr.urls(for: .documentDirectory, in: .userDomainMask)
    let recordSettings = [AVEncoderAudioQualityKey: AVAudioQuality.min.rawValue,
                      AVEncoderBitRateKey: 16,
                      AVNumberOfChannelsKey: 2,
                      AVSampleRateKey: 44100] as [String: Any]
    let soundFileUrl = dirPaths[0].appendingPathComponent("recording-" + getDate() + ".pcm")


    do {
        let audioFile = try AVAudioFile(forWriting: soundFileUrl, settings: recordSettings)
        let format = AVAudioFormat(commonFormat: .pcmFormatInt16, sampleRate: 44100, channels: 2, interleaved: true)

        let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: 3000)

        for i in 0..<circBuffer.count {
            audioFileBuffer.int16ChannelData?.pointee[i] = Int16(circBuffer[i])
        }

        try audioFile.write(from: audioFileBuffer)

    }

在最后一行，我收到一条错误消息：

错误：> avae> AVAudioFile.mm:306：-[AVAudioFile writeFromBuffer:error:]：错误-50幅值Demo（79264,0x70000f7cb000）malloc：*对象0x7fc5b9057e00的错误：已释放对象的校验和不正确-对象在被释放后可能被修改. *在 malloc_error_break 中设置断点进行调试

我已经搜索了很多其他问题，但找不到任何对我有帮助的东西。

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2 回答 2

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在此行的代码中：

let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: 3000)

您声明AVAudioPCMBuffer容量为 3000 帧 * 2 个通道，这意味着为您分配的缓冲区audioFileBuffer可以包含 6000 个样本。如果通道数据的索引超过此限制，您的代码会破坏堆中的附近区域，这会导致对象可能被修改错误。

所以，你circBuffer.count可能会超过这个限制。您需要为AVAudioPCMBuffer.

    do {
        //### You need to specify common format
        let audioFile = try AVAudioFile(forWriting: soundFileUrl, settings: recordSettings, commonFormat: .pcmFormatInt16, interleaved: true)

        let channels = 2
        let format = AVAudioFormat(commonFormat: .pcmFormatInt16, sampleRate: 44100, channels: AVAudioChannelCount(channels), interleaved: true)
        let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: AVAudioFrameCount(circBuffer.count / channels)) //<-allocate enough frames
        //### `stride` removed as it seems useless...
        let int16ChannelData = audioFileBuffer.int16ChannelData! //<-cannot be nil for the `format` above

        //When interleaved, channel data of AVAudioPCMBuffer is not as described in its doc:
        //  https://developer.apple.com/reference/avfoundation/avaudiopcmbuffer/1386212-floatchanneldata .
        //  The following code is modified to work with actual AVAudioPCMBuffer.
        //Assuming `circBuffer` as
        //  Interleaved, 2 channel, Float32
        //  Each sample is normalized to [-1.0, 1.0] (as usual floating point audio format)
        for i in 0..<circBuffer.count {
            int16ChannelData[0][i] = Int16(circBuffer[i] * Float(Int16.max))
        }
        //You need to update `frameLength` of the `AVAudioPCMBuffer`.
        audioFileBuffer.frameLength = AVAudioFrameCount(circBuffer.count / channels)

        try audioFile.write(from: audioFileBuffer)

    } catch {
        print("Error", error)
    }

一些注释作为注释添加，请在尝试此代码之前检查它们。

更新 抱歉，为了显示未经测试的代码，修复了两件事：

  • commonFormat:实例化时需要指定AVAudioFile。
  • int16ChannelData（和其他通道数据）在交错时不返回其文档中描述的预期指针，修改数据填充循环以适应实际行为。

请试试。

于 2017-01-05T17:01:34.533 回答
1

你似乎选择了frameCapacity随心所欲3000。

将其设置为实际样本数：

let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: AVAudioFrameCount(circBuffer.count))

于 2017-01-05T17:03:33.243 回答