iOS Swift malloc error

Question

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 Float 数组中，我想将其保存到音频文件中。我尝试使用以下代码执行此操作：

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，我收到一个错误，上面写着：

错误：>avae> AVAudioFile.mm:306： -[AVAudioFile writeFromBuffer：error：]： 错误 -50amplitudeDemo（79264,0x70000f7cb000） malloc： * 对象 0x7fc5b9057e00 的错误：释放对象的校验和不正确 - 对象可能在释放后被修改。* 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，但我找不到任何对我有帮助的东西。

Answer 1

在代码中，此行：

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

您声明了一个容量为 3000 帧 * 2 个通道的AVAudioPCMBuffer，这意味着为audioFileBuffer分配的缓冲区可以包含 6000 个样本。如果通道数据的索引超过此限制，则代码会销毁堆中的邻近区域，这会导致对象可能被修改错误。

因此，您的circBuffer.count可能会超过此限制。您需要为AVAudioPCMBuffer分配足够的缓冲区大小。

    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，显示未经测试的代码，修复了两件事：

• 实例化AVAudioFile时需要指定commonFormat:。
• 交错时，int16ChannelData（和其他通道数据）不会返回其文档中描述的预期指针，数据填充循环经过修改以适应实际行为。

请尝试。

Answer 2

您似乎任意选择了frameCapacity来3000 .

将其设置为实际样本计数：

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