C / C++ / MFC Discussion Boards

Brakanjan11-Jul-02 15:53

11-Jul-02 15:53

Is there source code available that shows how to append two wave (.wav) files, and how can information be extracted from a wave file (similar to the wavread and wavwrite functions in Matlab)

Re: Appending Wave files

KaЯl12-Jul-02 3:59

KaЯl

12-Jul-02 3:59

The wav format is a file format, which may contain several sound formats or encoding (one per file). That's why adding two wav file may need a conversion between two different sound formats, with a different sample frequencies and with different sample sizes. That's why it's not that easy to concatenate wav files.

You may find nice info about wav format at www.tsp.ece.mcgill.ca/Docs/AudioFormats/WAVE/WAVE.html

HTH,

We do not inherit the Earth from our ancestors. We borrow it from our children.

Antoine de Saint Exupéry (1900-1944)

Re: Appending Wave files

Jh313-Jul-02 22:35

Jh3

13-Jul-02 22:35

tx.

if the sampling rate and the bits per sampling is the same for both files, wouldn't it then be easier to concatenate?

How to let childWindow have same focus as parent ?

bisserke11-Jul-02 13:20

bisserke

11-Jul-02 13:20

Hi,

I got this modeless Dialog wich is created as a child of the main Frame ?
How can I make this Dialog always have the same focus as the Parent ? (the CMainFrame)

thx & greetz

I used to have a life ... now I have a computer

Re: How to let childWindow have same focus as parent ?

Nish Nishant11-Jul-02 14:51

Nish Nishant

11-Jul-02 14:51

If you mean, you don't want the modeless dialog to always be on top of the main frame window, then I can help you, else I guess I havent understood what you meant :-

Read - http://www.codeproject.com/dialog/gettingmodeless.asp

and scroll down to the scetion titled as "The parent issue"

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Do I need the latest Platform SDK?

BigCaot11-Jul-02 12:40

BigCaot

11-Jul-02 12:40

Hi,

I use some basic MSHTML interfaces for HTML parsing which are already present in IE 4, too. I tested my project on W2k/IE 5. Can there be any problems on XP/IE 6 when I don't use the latest platform SDK for my VC project?

Thanks

BC

Re: Do I need the latest Platform SDK?

Anders Molin11-Jul-02 12:46

Anders Molin

11-Jul-02 12:46

I should not give you any problems when you use an old platform sdk...

- Anders

Money talks, but all mine ever says is "Goodbye!"

VC++ 6.0 interface question

EBerlin11-Jul-02 12:14

EBerlin

11-Jul-02 12:14

OK so I have my project open and im looking at the current file and on the left is my workspace. Workspace has three tabs
ClassView
ResourceView
FileView

Sometimes, it appears random but im sure its something im doing, one of my classes dissapears from the ClassView. The #include files are still there and everything compiles fine I just cant see the class in the workspace. This also causes the wonderfull shortcuts where you type -> or . to access member functions to no longer work forcing me to look up class definitions of many libraries. Why does this happen and how can I stop it?

Eric

Re: VC++ 6.0 interface question

Christian Graus11-Jul-02 12:17

Christian Graus

11-Jul-02 12:17

Install Visual Assist. It will help with the . -> thing, and even turn . into -> where needed ( no good for smart pointers ).

Christian

come on all you MS suckups, defend your sugar-daddy now. - Chris Losinger - 11/07/2002

Re: VC++ 6.0 interface question

EBerlin12-Jul-02 7:04

EBerlin

12-Jul-02 7:04

Thanks for your help Chris

Re: VC++ 6.0 interface question

Rage11-Jul-02 22:12

Rage

11-Jul-02 22:12

This problem comes from a bad update of the .ncb file.

Send me a mail, and i´ll mail you back the OpenVC dll which installs an add-in in VC++ (a button which erases .NCB file and reopens your windows). It is very easy to do, and kicks ass.

~RaGE();

Re: System Busy...

Brad Bruce11-Jul-02 10:04

Brad Bruce

11-Jul-02 10:04

This is what I use...

BOOL DoEvents()
{
        MSG msg;
        while ( ::PeekMessage( &msg, NULL, 0, 0, PM_NOREMOVE ) )
        {
				if ( !AfxGetApp()->PumpMessage( ) )
                {
                        ::PostQuitMessage( 1 );
                        return FALSE;
                }
        }
        // let MFC do its idle processing
        LONG lIdle = 0;
        while (AfxGetApp()->OnIdle(lIdle++ ) )
                ;
        return TRUE;
}

doble to String...

Speedy11-Jul-02 9:37

Speedy

11-Jul-02 9:37

Is there any simple method to convert from double to CString(i have seen _ecvt(),_gcvt(),_fcvt() but too complex )i need something like Javas .toString(1234.4432) method.
THANX

Re: doble to String...

Joaquín M López Muñoz11-Jul-02 9:44

Joaquín M López Muñoz

11-Jul-02 9:44

Check for the Format member function for CStrings.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

random NUmbers

ib04212911-Jul-02 9:37

ib042129

11-Jul-02 9:37

Ok, here's the deal.
I got an "array" of 60 normal variables
and a separate "array" of 10 filler (fake) variables
I need to go through the "array" of 60 and
as I do I need to randomly place all the variables
of the "array" of 10 between some of those of the first array

if I just do something like if(rand()%(60/10))
use normal;
else
use filler;

I might not get all ten variable in. What algorythm should I use
to randomly run each of the 10 variables between the 60 normal ones, and to make sure I do not get a systematic large chunk of normal variables?

P.S. I don't know if what I said is very clear, sorry about that....

Re: random NUmbers

Joaquín M López Muñoz11-Jul-02 9:53

Joaquín M López Muñoz

11-Jul-02 9:53

Something like this should work:

int fillers_used=0;
for(int i=n;i<60;++i){
  if(fillers_used<10 && rand()%((60-i)/(10-fillers_used))) {
    //use normal
  }
  else{
    // use filler
    ++fillers_used;
  }
}

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: random NUmbers

ib04212911-Jul-02 10:07

ib042129

11-Jul-02 10:07

Thanks a lot...
but this way wouldn't the frequency of the filler used be increased as I go through the array?
(nnnnnnnnfnnnnnnnfnnnnnfnnnnfnnfnnff)?

Re: random NUmbers

Joaquín M López Muñoz11-Jul-02 11:09

Joaquín M López Muñoz

11-Jul-02 11:09

Well there's a deficiency due to truncation problems, I guess you should use something like this instead:

static double rand01()
{
  int r;
  while((r=rand())==RAND_MAX);
  return (double)rand/RAND_MAX;
}
...
if(rand01()<(double)(10-fillers_used)/(60-i)){
...

Apart from this, the process is unbiased. To prove this, we can use a little probability. Let's call P_n the probability that the process uses a filler value at position n. Also, let p=10/60, q=1-(10/60).Then:

P₀ = 10/60
P₁ = P₀·(9/59)+(1-P₀)·(10/59) = (10/60)·(9/59)+(50/60)·(10/59) = 590/3540 = 10/60
P_n = pⁿ·((10-n)/(60-n)) + p^n-1·q·((10-(n-1))/(60-n)) + ··· + qⁿ·(10/(60-n))

It can be formally proven that P_n = 10/60 for every n, but also a small test program doing the calculations will convince you.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

How to show File Preview in the Windows Explorer.

Ganesh Agrawal11-Jul-02 9:18

Ganesh Agrawal

11-Jul-02 9:18

I have an application written in MFC. The document data of the application contains the File Preview as form of Bitmap.
I show the File Preview in the File Open dialog of my application.

Now I want to enhance this to show the Thumbnail File Preview when the user selects the File in Windows Explorer. This is similar to what the .BMP & .JPEG File does. How can I make the OS aware and as to where the OS can look the File Preview in the File.

Thanks

Re: How to show File Preview in the Windows Explorer.

KaЯl12-Jul-02 5:01

KaЯl

12-Jul-02 5:01

"thumbnail preview" is based on .HTT template and a preview activeX. There's a good article on MSDN about this. Have a look to "More Windows 2000 UI Goodies: Extending Explorer Views by Customizing Hypertext Template Files" , msdn.microsoft.com/msdnmag/issues/0600/w2kui2/w2kui2.asp

HTH,

We do not inherit the Earth from our ancestors. We borrow it from our children.

Antoine de Saint Exupéry (1900-1944)

Re: How to show File Preview in the Windows Explorer.

Ganesh Agrawal12-Jul-02 6:25

Ganesh Agrawal

12-Jul-02 6:25

Thanks Karl.
I shall investigate & let you know after I have implemented it.

Wrong return type from CObList (newb question)

EBerlin11-Jul-02 8:25

EBerlin

11-Jul-02 8:25

ok I have a pointer to a COblist
CObList* m_Unsorted_Members = GetDocument()->Get_Unsorted();

and im inserting members of the class State. The State Class is inherited from CObject since CObList only takes CObject type.

Container = new State(Name, Loc, pop, area);
m_Bookmark = m_Unsorted_Members->AddTail(Container);

all is good
however when I try and retrieve a member from the list
State* pObject = m_Unsorted_Members->GetAt(m_Bookmark);

I get an error saying that it cant convert from type CObject* to State*
Why is GetAt(m_Bookmark) not returning the same type that I inserted and instead is returning the base class?

thanks in advance,
Eric

Problem Fixed

EBerlin11-Jul-02 8:30

EBerlin

11-Jul-02 8:30

Ok I just fixed my own problem (about 2 min after I wrote this post of course)

needed to add

State* pObject = (State*) m_Unsorted_Members->GetAt(m_Bookmark);

Is that extra code converting from base class to child class? I dont exactly understand the functionality of it.

Either way code works now

Re: Wrong return type from CObList (newb question)

jbarton11-Jul-02 9:12

jbarton

11-Jul-02 9:12

Instead of using CObList directly, you should use CTypedPtrList to make the list typesafe. You can put any pointer which is derived from CObject into a CObList. You also need to cast the value when you take it out of a CObList (which again could lead to errors if the actual pointer is not the type that you are casting it to).

To use CTypedPtrList to contain pointers to State objects, you can declare it as follows:

CTypedPtrList<CObList,State *> stateList;

This list works the same as CObList, except that you can only put State * objects into the list, and any objects you get from the list are State * objects.

So, this works:

m_Bookmark = stateList.AddTail( new State(Name,Loc,pop,area) );

And, this works:

State *pObject = stateList.GetAt( m_Bookmark ); // note: no cast

Best regards,
John

Re: Wrong return type from CObList (newb question)

EBerlin11-Jul-02 10:55

EBerlin

11-Jul-02 10:55

Thanks for your response. The reason I chose not to make the list typesafe is because I am under the impression that it is more dificult to perform serialization on lists of it is a CTypedPtrList. This is my first time performing serialization using MFC's DOC/VIEW structure as opposed to straight writing to text files.

Was my information correct or is serialization identical for both types of lists?

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