Access Violation?!

Thread View: borland.public.cppbuilder.multimedia

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3 total messages Started by Juampi David Thu, 23 Dec 2004 16:01

#269

Author: Juampi David
Date: Thu, 23 Dec 2004 16:01

45 lines
2333 bytes

Hello! ...

I'm workin' with DES on C++ Builder 5. When I try to change MediaSubType of 
one Video Group appears this "fatal error" messange:

Project Projecto1.exe raised exception class EAccessViolation with messange 
'Access violation at adress BAADF00D. Read of address BAADF00D'. Process 
stoped. Use Step or Run to continue.

This is the Code:

AM_MEDIA_TYPE mtGroup;
mtGroup.majortype = MEDIATYPE_Video;
mtGroup.subtype = MEDIASUBTYPE_RGB555;

mtGroup.pbFormat = (BYTE*)CoTaskMemAlloc(sizeof(VIDEOINFOHEADER));


VIDEOINFOHEADER *pVideoHeader = (VIDEOINFOHEADER*)mtGroup.pbFormat;
ZeroMemory(pVideoHeader, sizeof(VIDEOINFOHEADER));
pVideoHeader->bmiHeader.biBitCount = 16;
pVideoHeader->bmiHeader.biWidth = 320;
pVideoHeader->bmiHeader.biHeight = 240;
pVideoHeader->bmiHeader.biPlanes = 1;
pVideoHeader->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pVideoHeader->bmiHeader.biSizeImage = DIBSIZE(pVideoHeader->bmiHeader);

mtGroup.formattype = FORMAT_VideoInfo;
mtGroup.cbFormat = sizeof(VIDEOINFOHEADER);

mtGroup.bFixedSizeSamples = TRUE;
mtGroup.lSampleSize = DIBSIZE(pVideoHeader->bmiHeader);

IAMTimelineGroup        *pGroup;

pGroup->SetMediaType(&mtGroup);

CoTaskMemFree(mtGroup.pbFormat);

And the error appears when I add this line: pGroup->SetMediaType(&mtGroup);

Could anyone explain me why this error appears?!!?

Thanks!!!
Juampi David

Re: Access Violation?!

#270

Author: Remy Lebeau (TeamB)
Date: Thu, 23 Dec 2004 18:06

32 lines
1766 bytes

"Juampi David" <multimedia@mdpsistemas.com.ar> wrote in message
news:41caebfa@newsgroups.borland.com...

> IAMTimelineGroup        *pGroup;
>
> pGroup->SetMediaType(&mtGroup);

You are declaring an uninitialized pointer and not instantiating an
IAMTimelineGroup object before using it.  For example:

    IAMTimeline *pTimeline = NULL;
    IAMTimelineObj *pObj = NULL;
    IAMTimelineGroup *pGroup = NULL;

    // first obtain the Timeline as needed, then do one of the following as
needed ...

    pTimeline->CreateEmptyNode(&pObj, TIMELINE_MAJOR_TYPE_GROUP);
    // or ...
    pTimeline->GetGroup(&pObj, SomeIndex);

    // then obtain the Group...
    if( pObj )
    {
        pObj->QueryInterface(IID_IAMTimelineGroup, (LPVOID*)&pGroup);
        // now use the Group as needed...
        pGroup->Release();
    }


Gambit

Re: Access Violation?!

#271

Author: Juampi David
Date: Fri, 24 Dec 2004 01:17

80 lines
3396 bytes

Gambit ... Thanks for your help! ... and for your Time! ...

I found the solution on ...

1st ... Make a Timeline
2nd... Make a Group
3th... Adjust MediaSubType --->

AM_MEDIA_TYPE mtGroup;
ZeroMemory(&mtGroup, sizeof(AM_MEDIA_TYPE));
mtGroup.majortype = MEDIATYPE_Video;
pGroup->SetMediaType(&mtGroup);
mtGroup.majortype = MEDIATYPE_Video;
mtGroup.subtype = MEDIASUBTYPE_RGB24;
mtGroup.pbFormat = (BYTE*)CoTaskMemAlloc(sizeof(VIDEOINFOHEADER));
VIDEOINFOHEADER *pVideoHeader = (VIDEOINFOHEADER*)mtGroup.pbFormat;
ZeroMemory(pVideoHeader, sizeof(VIDEOINFOHEADER));
pVideoHeader->bmiHeader.biBitCount = 24;
pVideoHeader->bmiHeader.biWidth = 720;
pVideoHeader->bmiHeader.biHeight = 576;
pVideoHeader->bmiHeader.biPlanes = 1;
pVideoHeader->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pVideoHeader->bmiHeader.biSizeImage = DIBSIZE(pVideoHeader->bmiHeader);
mtGroup.formattype = FORMAT_VideoInfo;
mtGroup.cbFormat = sizeof(VIDEOINFOHEADER);
mtGroup.bFixedSizeSamples = TRUE;
mtGroup.lSampleSize = DIBSIZE(pVideoHeader->bmiHeader);
pGroup->SetMediaType(&mtGroup);
CoTaskMemFree(mtGroup.pbFormat);

4th. Adding Group to TimeLine

pTimeline->AddGroup(pGroupObj);
pGroupObj->Release();

And following....

Thanks and if you want, tell me if my solution is or not Rigth! ...

Thanks!!!

Juampi David


"Remy Lebeau (TeamB)" <no.spam@no.spam.com> escribi� en el mensaje 
news:41cb08f2$1@newsgroups.borland.com...
>
> "Juampi David" <multimedia@mdpsistemas.com.ar> wrote in message
> news:41caebfa@newsgroups.borland.com...
>
>> IAMTimelineGroup        *pGroup;
>>
>> pGroup->SetMediaType(&mtGroup);
>
> You are declaring an uninitialized pointer and not instantiating an
> IAMTimelineGroup object before using it.  For example:
>
>    IAMTimeline *pTimeline = NULL;
>    IAMTimelineObj *pObj = NULL;
>    IAMTimelineGroup *pGroup = NULL;
>
>    // first obtain the Timeline as needed, then do one of the following as
> needed ...
>
>    pTimeline->CreateEmptyNode(&pObj, TIMELINE_MAJOR_TYPE_GROUP);
>    // or ...
>    pTimeline->GetGroup(&pObj, SomeIndex);
>
>    // then obtain the Group...
>    if( pObj )
>    {
>        pObj->QueryInterface(IID_IAMTimelineGroup, (LPVOID*)&pGroup);
>        // now use the Group as needed...
>        pGroup->Release();
>    }
>
>
> Gambit
>
>

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