在尝试使用带有CALLBACK功能的midiInOpen时，为什么会出现访问冲突？ [英] Why am I getting an access violation when trying to use midiInOpen with CALLBACK function?
问题描述
我在尝试使用时不断收到访问权限：
无符号长结果;
HMIDIIN     inHandle;
result = midiInOpen（& inHandle，1，（DWORD）midiCallback，0，CALLBACK_FUNCTION）;
I尝试了一切。除了我，它似乎对每个人都有用。为什么在指定CALLBACK时会出现访问冲突？如果我只使用MidiInOpen（inHandle，0,0,0,0）它会运行 但没有办法处理事件..
更新：
访问冲突似乎只发生在我编译下64。在x86和Win32下编译它似乎解决了这个问题。有谁知道这是为什么？
#include" stdafx.h"
#include< iostream>
#include< cstdlib>
#include< windows.h>
#include< Mmsystem.h>
#include< stdio.h>
using namespace std;
void CALLBACK midiCallback（HMIDIIN句柄，UINT uMsg，DWORD dwInstance，DWORD dwParam1，DWORD dwParam2）
{
switch（uMsg）
{
case MIM_OPEN：
cout<< " ----- ----- OPENED" << ENDL;
休息;
case MIM_CLOSE：
cout<< "-----一切都在关闭.-----" << ENDL;
休息;
case MIM_DATA：
cout<< "-----显然是我的数据.-----" << ENDL;
休息;
case MIM_LONGDATA：
cout<< " ----- ----- LONGDATA'D" << ENDL;
休息;
case MIM_ERROR：
cout<< " ----- ----- ERROR" << ENDL;
休息;
case MIM_LONGERROR：
cout<< " ----- LONGERROR。 EVEN WORSE .-----" << ENDL;
休息;
}
cout<< "dwInstance is" << dwInstance<< ENDL;
cout<< "Handle is" <<句柄<< ENDL;
cout<< "dwParam1是" << dwParam1<< ENDL; // dwParam1是打包到unsigned long
cout<<<<<<<< "dwParam1_hiword是" << HIWORD（dwParam1）<< ENDL; // velocity
cout<< "dwParam1_loword是" << LOWORD（dwParam1）<< ENDL; // keyID
cout<< "dwParam2是" << dwParam2<< ENDL; // dwParam2是按键的时间戳
cout<< "uMsg是" << uMsg<< ENDL;
cout<< " -----" << ENDL;
}
无效MidiThing（）{
MIDIINCAPS麦克风;
未签名的长期结果;
HMIDIIN inHandle;
unsigned long iNumDevs，i;
iNumDevs = midiInGetNumDevs（）; / *获取此计算机中MIDI输入设备的数量* /
/ *浏览所有这些设备，显示其名称* /
for（i = 0; i< iNumDevs ; i ++）
{
/ *获取有关下一个设备的信息* /
if（！midiInGetDevCaps（i，& mic，sizeof（MIDIINCAPS）））
{
/ *显示其设备ID和名称* /
wcout<< "设备ID ["] << i<< "]：" << mic.szPname<< ENDL;
}
}
cout<< ENDL;
//打开默认的MIDI输入设备。 （DevID 0）
result = midiInOpen（& inHandle，1，（DWORD）midiCallback，0，CALLBACK_FUNCTION）;
// result = midiInOpen（& inHandle，0,0,0,0）;
if（result！= MMSYSERR_NOERROR）{
cout<< "midiInOpen（）失败... rv =" <<结果<< ENDL;
}
其他
{
midiInStart（inHandle）;
}
cout<< ENDL;
cout<< "按\"ESC \"退出。" << ENDL;
while（1）{
if（GetAsyncKeyState（VK_ESCAPE））
{
break;
cout<< "出口=真QUOT。 << ENDL;
}
睡眠（100）;
}
midiInStop（inHandle）;
midiInReset（inHandle）;
midiInClose（inHandle）;
cout<< ENDL;
cout<< inHandle<< "是MIDIIN句柄。" << ENDL;
cout<< ENDL;
cout<< "MIDI现在关闭。" << ENDL;
}
int main（int argc，char * argv []）
{
MidiThing（）;
cout<< "退出是成功的"。 << ENDL;
返回EXIT_SUCCESS;
}
Eric M Lieber
//打开默认的MIDI输入设备。 （DevID 0）
result = midiInOpen（& inHandle，1，（DWORD）midiCallback，0，CALLBACK_FUNCTION）;
您好，
在您的评论中写入DeviceId 0，但是你给了函数中的Id 1.
试试这个：
UINT deviceId = 0;
result = midiInOpen（& inHandle，deviceId，（DWORD_PTR）（void *）midiCallback，0，CALLBACK_FUNCTION）;查看文档：< a href ="https://msdn.microsoft.com/de-de/library/windows/desktop/dd798458(v=vs.85).aspx">
https://msdn.microsoft.com/ de-de / library / windows / desktop / dd798458（v = vs.85）.aspx
HTH，Guido
I keep getting an access violation when trying to use:
unsigned long result;HMIDIIN inHandle;
result = midiInOpen(&inHandle, 1, (DWORD)midiCallback, 0, CALLBACK_FUNCTION);
I have tried everything. It seems to work for everyone but me. Why would I get an access violation when specifying a CALLBACK? If I use just MidiInOpen(inHandle,0,0,0,0) it runs but there is no way to process events..
Update:
The access violation seem to only occur when I compile it under x64. Having compiled it under x86 and Win32 seems to resolve this problem. Does anyone know why this is?
#include"stdafx.h"
#include<iostream>
#include<cstdlib>
#include<windows.h>
#include<Mmsystem.h>
#include<stdio.h>
using namespace std;
void CALLBACK midiCallback(HMIDIIN handle, UINT uMsg, DWORD dwInstance, DWORD dwParam1, DWORD dwParam2)
{
switch (uMsg)
{
case MIM_OPEN:
cout << "-----OPENED.-----" << endl;
break;
case MIM_CLOSE:
cout << "-----EVERYTHING IS CLOSING.-----" << endl;
break;
case MIM_DATA:
cout << "-----APPARENTLY THERE I5 DATA.-----" << endl;
break;
case MIM_LONGDATA:
cout << "-----LONGDATA'D.-----" << endl;
break;
case MIM_ERROR:
cout << "-----ERROR.-----" << endl;
break;
case MIM_LONGERROR:
cout << "-----LONGERROR. EVEN WORSE.-----" << endl;
break;
}
cout << "dwInstance is " << dwInstance << endl;
cout << "Handle is " << handle << endl;
cout << "dwParam1 is " << dwParam1 << endl; //dwParam1 is the bytes of the MIDI Message packed into an unsigned long
cout << "dwParam1_hiword is " << HIWORD(dwParam1) << endl; //velocity
cout << "dwParam1_loword is " << LOWORD(dwParam1) << endl; //keyID
cout << "dwParam2 is " << dwParam2 << endl; //dwParam2 is the timestamp of key press
cout << "uMsg is " << uMsg << endl;
cout << "-----" << endl;
}
void MidiThing() {
MIDIINCAPS mic;
unsigned long result;
HMIDIIN inHandle;
unsigned long iNumDevs, i;
iNumDevs = midiInGetNumDevs(); /* Get the number of MIDI In devices in this computer */
/* Go through all of those devices, displaying their names */
for (i = 0; i < iNumDevs; i++)
{
/* Get info about the next device */
if (!midiInGetDevCaps(i, &mic, sizeof(MIDIINCAPS)))
{
/* Display its Device ID and name */
wcout << "Device ID [" << i << "]: " << mic.szPname << endl;
}
}
cout << endl;
// Open the default MIDI In device. (DevID 0)
result = midiInOpen(&inHandle, 1, (DWORD)midiCallback, 0, CALLBACK_FUNCTION);
// result = midiInOpen(&inHandle, 0, 0, 0, 0);
if (result != MMSYSERR_NOERROR) {
cout << "midiInOpen() failed...rv= " << result << endl;
}
else
{
midiInStart(inHandle);
}
cout << endl;
cout << "Press \"ESC\" to quit." << endl;
while (1) {
if (GetAsyncKeyState(VK_ESCAPE))
{
break;
cout << "exit=true." << endl;
}
Sleep(100);
}
midiInStop(inHandle);
midiInReset(inHandle);
midiInClose(inHandle);
cout << endl;
cout << inHandle << " was the MIDIIN handle." << endl;
cout << endl;
cout << "MIDI is closed now." << endl;
}
int main(int argc, char *argv[])
{
MidiThing();
cout << "Exit is success." << endl;
return EXIT_SUCCESS;
}
Eric M Lieber
// Open the default MIDI In device. (DevID 0) result = midiInOpen(&inHandle, 1, (DWORD)midiCallback, 0, CALLBACK_FUNCTION);
Hello,
in your comment you write DeviceId 0, but you give Id 1 in the function.
Try this:
UINT deviceId = 0; result = midiInOpen(&inHandle, deviceId, (DWORD_PTR)(void*)midiCallback, 0, CALLBACK_FUNCTION);Have a look at the documentation: https://msdn.microsoft.com/de-de/library/windows/desktop/dd798458(v=vs.85).aspx
HTH, Guido
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