Interop C++/CLI noob:System.AccessViolationException

我正试图在5天内为我女儿高中的职业生涯日准备一个“酷炫的演示”，所以我正试图用它来执行空中传送（OTA）音频识别。我从来没有真正的比“Hello World”在C++中做得更远，我尝试用C++/CLI来封装ECHOPLUNT代码库，这样我就可以从C++调用它。这是我的头文件：

// echoprint-cli.h

#pragma once

#include "Codegen.h";

using namespace System;

namespace echoprintcli {

    public ref class CodegenCLI
    {
    public:
        String^ getCodeString(array<float>^ buffer, unsigned int samples, int start_offset);
    };
}

我想象它在Init（）方法的某个地方爆炸：

    void Whitening::Init() {
    int i;
    _p = 40;

    _R = (float *)malloc((_p+1)*sizeof(float));
    for (i = 0; i <= _p; ++i)  { _R[i] = 0.0; }
    _R[0] = 0.001;

    _Xo = (float *)malloc((_p+1)*sizeof(float));
    for (i = 0; i < _p; ++i)  { _Xo[i] = 0.0; }

    _ai = (float *)malloc((_p+1)*sizeof(float));
    _whitened = (float*) malloc(sizeof(float)*_NumSamples);
}

void美白：：Init（）{
int i；
_p=40；
_R=（浮动*）malloc（（_p+1）*浮动大小）；
对于EchoNest论坛上承诺的（i=0；i，以下是我的方法。如果修改codegen.dll并提供合适的导出函数，您可以更轻松地使用CLI

要在codegen中添加
main.cxx
，请添加以下方法：

extern "C" __declspec(dllexport) void GetCodeStringFromPcm(const float* pcm, uint numSamples, int start_offset, BSTR* sResultString)
{
  // pcm: a buffer of floats, mono, 11025 Hz
  Codegen * pCodegen = new Codegen(pcm, numSamples, start_offset);
  string code = pCodegen->getCodeString();

  // http://stackoverflow.com/questions/2573834/c-convert-string-or-char-to-wstring-or-wchar-t
  std::wstring ws(code.size(), L' '); // Overestimate number of code points.
  ws.resize(mbstowcs(&ws[0], code.c_str(), code.size())); // Shrink to fit.

  *sResultString = SysAllocStringLen(ws.data(), ws.size());
}

现在在C#端，您可以简单地执行以下操作：

/// <summary>
/// Generates audio fringerprint for usage with Echonest.
/// </summary>
/// <param name="pcm">const float*, 4 byte per float in C++</param>
[DllImport("codegen.dll")]
private static extern void GetCodeStringFromPcm(float[] pcm, uint numSamples, int start_offset, [MarshalAs(UnmanagedType.BStr)] ref string sResultString);

//
///生成用于Echonest的音频边缘打印。
/// 
//const浮点*，C++中的每个浮点4字节
[DllImport（“codegen.dll”）]
private static extern void GetCodeStringFromPcm（float[]pcm，uint numSamples，int start_offset，[MarshalAs（UnmanagedType.BStr）]ref string sResultString）；

现在，对于第一个参数，您只需要这个特殊的浮点缓冲区。您提到已经有了一个，但作为对所有拥有其他格式音频数据的人的奖励，下面是一种将几乎所有音频文件转换为正确的浮点缓冲区的方法。要求如下：

使用BassLib=Un4seen.Bass.Bass；
使用BassMix=Un4seen.Bass.AddOn.Mix.BassMix；
/// 
///使用codegen.dll为音频曲目创建指纹代码。
/// 
公共字符串GetCodeStringFromFile（字符串文件名）
{
//读取输入流
int streamIn=BassLib.BASS_StreamCreateFile（文件名，0，0，Un4seen.BASS.basslafg.BASS_STREAM_DECODE）；
if（streamIn==0）返回null；
//新的混音器流，允许我们读取浮点样本。EchoNest需要单声道数据。
int mixerStream=BassMix.BASS_Mixer_StreamCreate（targetSampleRate，1，Un4seen.BASS.bassfagal.BASS_STREAM_DECODE | Un4seen.BASS.bassfagal.BASS_SAMPLE_FLOAT）；
BassMix.BASS_Mixer_StreamAddChannel（混音器流、streamIn、Un4seen.BASS.BASSFlag.BASS_STREAM_解码| Un4seen.BASS.BASSFlag.BASS_Mixer_DOWNMIX）；
long bufferSizeInBytes=BassLib.BASS_ChannelSeconds2Bytes（混音器流，0.1f）；
double totalSeconds=BassLib.BASS_ChannelBytes2秒（streamIn，BassLib.BASS_ChannelGetLength（streamIn））；
//以任何需要的方式使用进度数据。
int progress=0；
List resultData=新列表（）；
while（true）
{
浮点[]数据=新浮点[bufferSizeInBytes/4]；
int readBytes=BassLib.BASS_ChannelGetData（混音器流，数据，（int）缓冲大小字节）；
如果（readBytes当您调试到本机代码时会发生什么？您是否在项目设置中打开了“本机调试”？您好，floele，请您向我提供经过编辑的DLL，因为我在编译该DLL时遇到很多问题project@alizx当然，这里下载，这里是ENMFP和Echoprint签名生成器dll都有相同的codegen.dll名称？这让我有点困惑！！@alixx不确定它们是否具有相同的DLL名称。但我创建的DLL仅用于EchoPrint。您好（您知道）您是否使用Windows CLI通过EchoPrint标记或检索文件？谢谢！
    Codegen::Codegen(const float* pcm, unsigned int numSamples, int start_offset) {
    if (Params::AudioStreamInput::MaxSamples < (uint)numSamples)
        throw std::runtime_error("File was too big\n");

    Whitening *pWhitening = new Whitening(pcm, numSamples); //System.AccessViolationException

    Whitening::Whitening(const float* pSamples, uint numSamples) :
    _pSamples(pSamples), _NumSamples(numSamples) {
    Init();
}

    void Whitening::Init() {
    int i;
    _p = 40;

    _R = (float *)malloc((_p+1)*sizeof(float));
    for (i = 0; i <= _p; ++i)  { _R[i] = 0.0; }
    _R[0] = 0.001;

    _Xo = (float *)malloc((_p+1)*sizeof(float));
    for (i = 0; i < _p; ++i)  { _Xo[i] = 0.0; }

    _ai = (float *)malloc((_p+1)*sizeof(float));
    _whitened = (float*) malloc(sizeof(float)*_NumSamples);
}

extern "C" __declspec(dllexport) void GetCodeStringFromPcm(const float* pcm, uint numSamples, int start_offset, BSTR* sResultString)
{
  // pcm: a buffer of floats, mono, 11025 Hz
  Codegen * pCodegen = new Codegen(pcm, numSamples, start_offset);
  string code = pCodegen->getCodeString();

  // http://stackoverflow.com/questions/2573834/c-convert-string-or-char-to-wstring-or-wchar-t
  std::wstring ws(code.size(), L' '); // Overestimate number of code points.
  ws.resize(mbstowcs(&ws[0], code.c_str(), code.size())); // Shrink to fit.

  *sResultString = SysAllocStringLen(ws.data(), ws.size());
}

/// <summary>
/// Generates audio fringerprint for usage with Echonest.
/// </summary>
/// <param name="pcm">const float*, 4 byte per float in C++</param>
[DllImport("codegen.dll")]
private static extern void GetCodeStringFromPcm(float[] pcm, uint numSamples, int start_offset, [MarshalAs(UnmanagedType.BStr)] ref string sResultString);

using BassLib = Un4seen.Bass.Bass;
using BassMix = Un4seen.Bass.AddOn.Mix.BassMix;

/// <summary>
/// Creates a fingerprint code for an audio track, using the codegen.dll.
/// </summary>
public string GetCodeStringFromFile(string fileName)
{
    // Read input stream
    int streamIn = BassLib.BASS_StreamCreateFile(fileName, 0, 0, Un4seen.Bass.BASSFlag.BASS_STREAM_DECODE);
    if (streamIn == 0) return null;

    // New mixer stream that allows us to read floating point samples. EchoNest requires mono data.
    int mixerStream = BassMix.BASS_Mixer_StreamCreate(targetSampleRate, 1, Un4seen.Bass.BASSFlag.BASS_STREAM_DECODE | Un4seen.Bass.BASSFlag.BASS_SAMPLE_FLOAT);
    BassMix.BASS_Mixer_StreamAddChannel(mixerStream, streamIn, Un4seen.Bass.BASSFlag.BASS_STREAM_DECODE | Un4seen.Bass.BASSFlag.BASS_MIXER_DOWNMIX);

    long bufferSizeInBytes = BassLib.BASS_ChannelSeconds2Bytes(mixerStream, 0.1f);
    double totalSeconds = BassLib.BASS_ChannelBytes2Seconds(streamIn, BassLib.BASS_ChannelGetLength(streamIn));

    // Use progress data in whatever way you need it.
    int progress = 0;
    List<float> resultData = new List<float>();

    while (true)
    {
        float[] data = new float[bufferSizeInBytes / 4];
        int readBytes = BassLib.BASS_ChannelGetData(mixerStream, data, (int)bufferSizeInBytes);
        if (readBytes <= 0) break;

        for (int i = 0; i < readBytes / 4; i++)
        {
            resultData.Add(data[i]);
        }

        double secondsPos = BassLib.BASS_ChannelBytes2Seconds(mixerStream, BassLib.BASS_ChannelGetPosition(mixerStream));
        progress = (int)(secondsPos / totalSeconds * 100);
    }

    BassLib.BASS_StreamFree(streamIn);
    BassLib.BASS_StreamFree(mixerStream);

    // We need to pass an array of samples to C.
    float[] resultArray = resultData.ToArray();

    // Clear list to prevent occupying too much memory.
    resultData.Clear();

    // Marshaller will pass float[] just fine to C.
    string resultCodegenData = string.Empty;
    GetCodeStringFromPcm(resultArray, (uint)resultArray.Length, 0, ref resultCodegenData);

    return resultCodegenData;
}