英文:
It is not possible to correctly write functions from MSDN in Delphi
问题
抱歉，我无法直接提供对代码进行修复的帮助。然而，你的代码看起来可能出现了一些问题。一般来说，Access Violation 错误通常是由于内存访问错误引起的。你的代码中可能存在一些潜在的问题，如未初始化的指针、内存泄漏、参数传递错误等。
在你的代码中，一些潜在的问题可能包括：
-
pEnum没有初始化。在GetUnconnectedPin函数中，你在使用pFilter.EnumPins(pEnum);之前，应该为pEnum分配内存或实例化。 -
可能会有内存泄漏。你在使用 COM 接口时需要适时地释放使用过的资源，确保在使用完接口后进行正确的释放操作，比如调用
_Release。 -
参数传递问题。确保你在调用函数时传递的参数是正确的、符合预期的。比如
AddFilterByCLSID中，你调用了pGraph.AddFilter(pF, WazName);，但是可能是错误地传递了WazName而不是wazName。 -
COM 接口调用。在使用 DirectShow 中的 COM 接口时，确保你正确地使用了接口、实现了接口的所有方法并检查了返回值，以便在出现问题时能够捕捉到异常。
要解决这些问题，你需要逐一检查代码，确认每一步的操作都是正确的，并且正确处理了接口的初始化、调用和释放操作。
此外，还可以尝试使用调试工具、日志记录或逐步调试功能来找到错误所在。逐步调试能够帮助你逐行检查代码，找到程序执行时的问题所在。
最后，记得在修改代码之前创建备份，以防不慎破坏了原有的代码。
英文:
I want to create my own filter and use it in the DirectShow library. The filter seemed to be able to write, but there was a problem with creating a graph. I based my code on the "Creating an Audio Capture Graph" article. At the very end it says that the functions from the articles "Add a Filter by CLSID" and "Connect Two Filters" are also used. I rewrote the most identical, but the code does not work.
I indicated the location of the error with many "!".
> Project Project1.exe raised exception class AEccessViolation with message 'Access violation at address 0045AAA8 in module 'Project1.exe'. Read of address 00000000'. Process stopped. Use step or Run to continue.
In general, I have the following code:
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, DirectShow9,ActiveX,BaseClass, DirectInput,
StdCtrls,DirectSound, DirectSetup, DirectPlay8, DirectMusic,
Dialogs;
type
TForm1 = class(TForm)
Button1: TButton;
ListBox2: TListBox;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
function AddFilterByCLSID(pGraphA: IGraphBuilder; clsid: TGUID; wazName: PWideChar; ppF: IBaseFilter): HRESULT;
function ConnectFilter( pGraph: IGraphBuilder; pSrc: IBaseFilter; pdest: IBaseFilter): HRESULT;
function GetUnconnectedPin(pFilter: IBaseFilter; PinDir: PIN_DIRECTION; ppPin: IPin): HRESULT;
function ConnectFilterPin( pGraph: IGraphBuilder; pOut: IPin; pdest: IBaseFilter): HRESULT;
end;
var
PropertyName:IPropertyBag;
pSrc, pWaveDest, pWriter: IBaseFilter;
pSink: IFileSinkFilter;
pGraph: IGraphBuilder;
FMediaControl: IMediaControl;
pDevEnum: ICreateDevEnum;
pEnum: IEnumMoniker;
pMoniker: IMoniker;
MArray1,MArray2: array of IMoniker;
hr: HRESULT;
DeviceName:OleVariant;
FAudioCaptureFilter: IBaseFilter;
const
CLSID_WavDest : TGUID = '{3C78B8E2-6C4D-11d1-ADE2-0000F8754B99}';
CLSID_CRleFilter: TGUID = '{BEBCF0A3-2673-42A7-82F2-5D4FC3126171}'; //My Filter.
IID_ICRleFilter: TGUID = '{35C0AC80-C3E4-4EEA-A1F5-049401E29400}'; //Myfilter
var
Form1: TForm1;
implementation
{$R *.dfm}
function TForm1.AddFilterByCLSID(pGraphA: IGraphBuilder; clsid: TCLSID;
wazName: PWideChar; ppF: IBaseFilter): HRESULT;
var
pF: IBaseFilter;
begin
CoCreateInstance(clsid, nil, CLSCTX_INPROC_SERVER, IID_IBaseFilter, pF);
hr:=pGraph.AddFilter(pF, WazName);
if hr<> S_OK then
begin
ShowMessage('фильтр вавдеста не добавился');
end;
PPf:= pF;
// pF._Release;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
pOut: IPin;
begin
HR:= CoCreateInstance(CLSID_FilterGraph, nil, CLSCTX_INPROC_SERVER,
IID_IGraphBuilder, pGraph);
if hr<> S_OK then
begin
ShowMessage('Граф не создался');
end;
HR:= CoCreateInstance(CLSID_SystemDeviceEnum, NIL, CLSCTX_INPROC_SERVER,
IID_ICreateDevEnum, pDevEnum);
if hr<> S_OK then
begin
ShowMessage('перечеслитель не создался');
Exit;
end;
HR:=pDevEnum.CreateClassEnumerator(CLSID_AudioInputDeviceCategory, pEnum, 0);
if HR<>S_OK then EXIT;
//Обнуляем массив в списке моникеров
setlength(MArray2,0);
//Пускаем массив по списку устройств
while (S_OK=pEnum.Next(1,pMoniker,Nil)) do
begin
setlength(MArray2,length(MArray2)+1); //Увеличиваем массив на единицу
MArray2[length(MArray2)-1]:=pMoniker; //Запоминаем моникер в масиве
HR:=pMoniker.BindToStorage(NIL, NIL, IPropertyBag, PropertyName); //Линкуем моникер устройства к формату хранения IPropertyBag
if FAILED(HR) then Continue;
HR:=PropertyName.Read('FriendlyName', DeviceName, NIL); //Получаем имя устройства
if FAILED(HR) then Continue;
//Добавляем имя устройства в списки
Listbox2.Items.Add(DeviceName);
end;
Listbox2.ItemIndex:=0;
MArray2[Listbox2.ItemIndex].BindToObject(NIL, NIL, IID_IBaseFilter, FAudioCaptureFilter);
//добавляем устройство в граф фильтров
Pgraph.AddFilter(FAudioCaptureFilter, 'AudioCaptureFilter');
// pGraph.AddFilter(pSrc, 'Capture');
AddfilterByCLSID(pGraph, CLSID_CRleFilter, '_CRleFilter', pWaveDest);
ConnectFilter(pGraph, pWaveDest, pWriter); // This is where the mistakes start !!!!!!!!!!!!!!!!!
pGraph.QueryInterface(IID_IMediaControl, FMediaControl);
FMediaControl.Run();
end;
{
There is no function overloading in Delphi, so I named the functions differently
}
function TForm1.ConnectFilterPin(pGraph: IGraphBuilder; pOut: IPin;
pdest: IBaseFilter): HRESULT;
var
pIn : IPin;
begin
pIn:= nil;
GetUnconnectedPin(pdest, PINDIR_OUTPUT, pIn);
pGraph.Connect(pOut, pin);
end;
function TForm1.ConnectFilter(pGraph: IGraphBuilder; pSrc: IBaseFilter;
pdest: IBaseFilter): HRESULT;
var
pOut: IPin;
begin
//pOut:= 0;
GetUnconnectedPin(pSrc, PINDIR_OUTPUT, pOut);
ConnectFilterPin(pGraph, pOut, pdest);
end;
function TForm1.GetUnconnectedPin(pFilter: IBaseFilter;
PinDir: PIN_DIRECTION; ppPin: IPin): HRESULT;
var
pEnum: IEnumPins;
pPin: IPin;
hr: HRESULT;
ThisPinDir : PIN_DIRECTION;
pTmp: IPin;
begin
pTmp:=nil;
ppPin:= nil;
// pEnum:= nil;
pPin:= nil;
hr:= pFilter.EnumPins(pEnum); // This is where the error occurs !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
if hr<> S_OK then
begin
ShowMessage('перечесление пинов: не равно S_OK');
end;
while pEnum.Next(1, pPin, nil) = S_OK do
begin
pPin.QueryDirection(ThisPinDir);
if ThisPinDir = PinDir then
begin
hr:= pPin.ConnectedTo(pTmp);
if Succeeded(hr) then
begin
pTmp._Release;
end else
begin
pEnum._Release;
ppPin:= pPin;
Result := S_OK;
Exit;
end;
end;
end;
pPin._Release;
ShowMessage('ошибка: не правильный код');
Result:= E_FAIL;
// ShowMessage('ошибка: не правильный код');
end;
end.
I was hoping that the error was caused by pointers, or rather their absence. I tried to put them in absolutely all combinations, but this did not lead to the desired result. Besides, everywhere in Delphi pointers are not used at all. Perhaps somewhere the parameters in the functions are not correctly passed. I reviewed all the functions 5 times, tried to find errors, but this did not work. Using pointers didn't work either.
I know the error is small and easy to fix, but I can't figure out where it is.
答案1
得分: 1
以下是代码部分的翻译：
The error was not in the pointers. The purpose of the `Connect Filter` function is to connect two filters. The structure looks like this `ConnectFilter(Graph, Filter 1, Filter 2);`. I added only one filter to the project. As a result, nothing was sent to the function instead of the second filter. There was an address reading error that was very hard to catch. Perhaps it would be easy to identify the error if I used all sorts of checks. Due to the fact that C ++ uses pointers, but Delphi does not, I thought that the error was in pointers, because I did not use them. But the fix turned out to be simpler: you need to add a second filter, and send it as the third parameter.
这个错误并不是指针的问题。`Connect Filter` 函数的目的是连接两个滤波器。结构如下：`ConnectFilter(Graph, Filter 1, Filter 2);`。我只添加了一个滤波器到项目中。结果是，第二个滤波器没有被发送到函数中，而是什么都没有。存在一个很难发现的地址读取错误。也许如果我使用了各种检查，就能更容易地识别错误。由于C++使用指针，而Delphi不使用指针，所以我认为错误在于指针，因为我没有使用它们。但修复方法却更简单：需要添加第二个滤波器，并将其作为第三个参数发送。
From these errors we can conclude:
1. Even in experimental code, it is worth doing as many checks as possible.
从这些错误中，我们可以得出以下结论：
1. 即使在实验性的代码中，尽量进行尽可能多的检查。
2. Watch and read carefully.
2. 仔细观察和阅读。
3. Functions that are called from other functions should be above these functions. There was no error, but it is indicated in the book Flenov M.E. The Bible of Delphi (third edition), chapter 5.4: Procedures and functions in Delphi. Solutions to other errors are also described there.
3. 从其他函数调用的函数应该位于这些函数之上。虽然没有错误，但在 Flenov M.E. 的书《Delphi圣经》（第三版）中指出了这一点，第5.4章：Delphi中的过程和函数。书中还描述了其他错误的解决方法。
4. Unlike C++, Delphi does not need to assign `nil` to new variables, Delphi does it on its own.
4. 与C++不同，Delphi不需要为新变量赋值 `nil`，Delphi会自动处理。
5. You also don't need to call `Release` yourself.
5. 你也不需要自己调用 `Release`。
I rewrote the code with the correction of all the errors I noticed. I'll leave it below:
我重写了代码，修复了我注意到的所有错误。以下是修正后的代码：
请注意，上述翻译仅涵盖了代码部分，不包括注释和说明性文字。如果您需要有关代码注释或其他文本的翻译，请提供具体的文本部分，我将尽力为您提供翻译。
英文:
The error was not in the pointers. The purpose of the Connect Filter function is to connect two filters. The structure looks like this ConnectFilter(Graph, Filter 1, Filter 2);. I added only one filter to the project. As a result, nothing was sent to the function instead of the second filter. There was an address reading error that was very hard to catch. Perhaps it would be easy to identify the error if I used all sorts of checks. Due to the fact that C ++ uses pointers, but Delphi does not, I thought that the error was in pointers, because I did not use them. But the fix turned out to be simpler: you need to add a second filter, and send it as the third parameter.
From these errors we can conclude:
- Even in experimental code, it is worth doing as many checks as possible.
- Watch and read carefully.
- Functions that are called from other functions should be above these functions. There was no error, but it is indicated in the book Flenov M.E. The Bible of Delphi (third edition), chapter 5.4: Procedures and functions in Delphi. Solutions to other errors are also described there.
- Unlike C++, Delphi does not need to assign
nilto new variables, Delphi does it on its own. - You also don't need to call
Releaseyourself.
I rewrote the code with the correction of all the errors I noticed. I'll leave it below:
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, DirectShow9,ActiveX,BaseClass, DirectInput,
StdCtrls,DirectSound, DirectSetup, DirectPlay8, DirectMusic,
Dialogs;
type
TForm1 = class(TForm)
Button1: TButton;
ListBox2: TListBox;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
function AddFilterByCLSID(pGraphA: IGraphBuilder; clsid: TGUID; wazName: PWideChar; var ppF: IBaseFilter): HRESULT;
function ConnectFilter( pGraph: IGraphBuilder; pSrc: IBaseFilter; pdest: IBaseFilter): HRESULT;
function GetUnconnectedPin(pFilter: IBaseFilter; PinDir: PIN_DIRECTION; var ppPin: IPin): HRESULT;
function ConnectFilterPin( pGraph: IGraphBuilder; pOut: IPin; pdest: IBaseFilter): HRESULT;
end;
var
PropertyName:IPropertyBag;
pSrc, pWaveDest, pWriter: IBaseFilter;
pSink: IFileSinkFilter;
pGraph: IGraphBuilder;
FMediaControl: IMediaControl;
pDevEnum: ICreateDevEnum;
pEnum: IEnumMoniker;
pMoniker: IMoniker;
MArray1,MArray2: array of IMoniker;
hr: HRESULT;
DeviceName:OleVariant;
FAudioCaptureFilter: IBaseFilter;
const
CLSID_WavDest : TGUID = '{3C78B8E2-6C4D-11d1-ADE2-0000F8754B99}';
CLSID_CRleFilter: TGUID = '{BEBCF0A3-2673-42A7-82F2-5D4FC3126171}';
IID_ICRleFilter: TGUID = '{35C0AC80-C3E4-4EEA-A1F5-049401E29400}';
var
Form1: TForm1;
implementation
{$R *.dfm}
function TForm1.AddFilterByCLSID(pGraphA: IGraphBuilder; clsid: TCLSID;
wazName: PWideChar; var ppF: IBaseFilter): HRESULT;
{The last parameter of the function is returned,
for this you need to add [ var ] before the declaration.
Возвращается последний параметр функции,
для этого вам нужно добавить [ var ] перед объявлением.}
var
pf: IBaseFilter;
begin
hr:= CoCreateInstance(clsid, nil, CLSCTX_INPROC_SERVER, IID_IBaseFilter, pF);
if Succeeded(hr) then // Added full error checking
begin
hr:=pGraph.AddFilter(pF, WazName);
if Succeeded(hr) then
begin
ppf:= pf;
end else
ShowMessage('фильтр добавился / Filter not added');
end else
ShowMessage('фильтр добавился / Filter not added 2');
Result:= hr;
end;
function TForm1.GetUnconnectedPin(pFilter: IBaseFilter;
PinDir: PIN_DIRECTION; var ppPin: IPin): HRESULT;
var
pEnum: IEnumPins;
pPin: IPin;
hr: HRESULT;
ThisPinDir : PIN_DIRECTION;
pTmp: IPin;
begin
//you don't need to assign [ nil ]; Delphi does it by itself.
//Не нужно явно указывать [ nil ]; Delphi делает это самостоятельно.
hr:= pFilter.EnumPins(pEnum);
if Failed(hr) then
begin
ShowMessage('перечесление пинов: ошибка / pin listing: error');
end;
while pEnum.Next(1, pPin, nil) = S_OK do
begin
pPin.QueryDirection(ThisPinDir);
if ThisPinDir = PinDir then
begin
hr:= pPin.ConnectedTo(pTmp);
if Succeeded(hr) then
begin
end else
begin
ppPin:= pPin;
Result := S_OK;
Exit;
end;
end;
end;
ShowMessage('ошибка: не правильный код / error: invalid code');
Result:= E_FAIL;
end;
function TForm1.ConnectFilterPin(pGraph: IGraphBuilder; pOut: IPin;
pdest: IBaseFilter): HRESULT;
var
pIn : IPin;
begin
GetUnconnectedPin(pdest, PINDIR_OUTPUT, pIn);
pGraph.Connect(pOut, pin);
end;
function TForm1.ConnectFilter(pGraph: IGraphBuilder; pSrc: IBaseFilter;
pdest: IBaseFilter): HRESULT;
var
pOut: IPin;
begin
GetUnconnectedPin(pSrc, PINDIR_OUTPUT, pOut);
ConnectFilterPin(pGraph, pOut, pdest);
end;
procedure TForm1.Button1Click(Sender: TObject);
var
pOut: IPin;
begin
HR:= CoCreateInstance(CLSID_FilterGraph, nil, CLSCTX_INPROC_SERVER,
IID_IGraphBuilder, pGraph);
if hr<> S_OK then
begin
ShowMessage('Ошибка создания графа / Graph creation error');
end;
HR:= CoCreateInstance(CLSID_SystemDeviceEnum, NIL, CLSCTX_INPROC_SERVER,
IID_ICreateDevEnum, pDevEnum);
if hr<> S_OK then
begin
ShowMessage('Ошибка создания графа / Graph creation error');
Exit;
end;
HR:=pDevEnum.CreateClassEnumerator(CLSID_AudioInputDeviceCategory, pEnum, 0);
if HR<>S_OK then EXIT;
//Обнуляем массив в списке моникеров / Resetting the array in the list of monikers
setlength(MArray2,0);
//Пускаем массив по списку устройств / Let's run the array through the list of devices
while (S_OK=pEnum.Next(1,pMoniker,Nil)) do
begin
setlength(MArray2,length(MArray2)+1); //Увеличиваем массив на единицу / Incrementing the array by one
MArray2[length(MArray2)-1]:=pMoniker; //Запоминаем моникер в масиве / Remembering the moniker in the array
HR:=pMoniker.BindToStorage(NIL, NIL, IPropertyBag, PropertyName); //Линкуем моникер устройства к формату хранения IPropertyBag
// Link Device Monitor to IPropertyBag Storage Format
if FAILED(HR) then Continue;
HR:=PropertyName.Read('FriendlyName', DeviceName, NIL); //Получаем имя устройства / Getting the device name
if FAILED(HR) then Continue;
//Добавляем имя устройства в списки / Adding the device name to the lists
Listbox2.Items.Add(DeviceName);
end;
Listbox2.ItemIndex:=0;
MArray2[Listbox2.ItemIndex].BindToObject(NIL, NIL, IID_IBaseFilter, FAudioCaptureFilter);
//добавляем устройство в граф фильтров / adding a device to the filter graph
Pgraph.AddFilter(FAudioCaptureFilter, 'AudioCaptureFilter');
AddfilterByCLSID(pGraph, CLSID_FileWriter, 'File Writer', pWriter);
AddfilterByCLSID(pGraph, CLSID_CRleFilter, '_CRleFilter', pWaveDest);
{The error was that [ ConnectFilter ] connects two filters, and only one was specified.
The first filter is specified in the second parameter; the second filter is
specified in the third parameter; In order for the function to execute correctly,
you must first add two filters, then use [ ConnectFilter ] }
{Ошибка заключалась в том что [ ConnectFilter ] соединяет два фильтра,
а задавался только один. Первый фильтр указан во втором параметре;
второй фильтр указывается в третьем параметре; Что бы функция выполнилась правильно,
нужно предварительно добавить два фильтра, затем использовать [ ConnectFilter ] }
ConnectFilter(pGraph, FAudioCaptureFilter, pWaveDest);
ConnectFilter(pGraph, pWaveDest, pWriter);
pGraph.QueryInterface(IID_IMediaControl, FMediaControl);
FMediaControl.Run();
end;
end.
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