iOS Swift malloc 错误

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。我正在使用此代码记录数据：https://gist.github.com/hotpaw2/ba815fc23b5d642705f2b1dedfaf0107

现在，我的数据保存在一个 Float 数组中，我想将它保存到一个音频文件中。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 amplitudeDemo(79264,0x70000f7cb000) malloc: * 对象 0x7fc5b9057e00 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 设置断点调试

我已经搜索了很多其他问题，但找不到任何对我有帮助的问题。

Answer 1

在您的代码中这一行：

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

您声明了一个容量为 3000 帧 * 2 个通道的 AVAudioPCMBuffer，这意味着为您的 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，您的代码会破坏堆中的附近区域，这会导致 object was probably was modified 错误。

所以，您的 circBuffer.count 可能超出了这个限制。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)
    }

添加了一些注释作为注释，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，已修复两个问题：

实例化AVAudioFile时需要指定commonFormat:。
int16ChannelData（和其他通道数据）不return交错时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。

请尝试。

Answer 2

你好像乱选了frameCapacity到3000。

设置为实际样本数：

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

iOS Swift malloc 错误

iOS Swift malloc error

malloc

audio

ios

swift

avaudiofile