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# DirectSound

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Hi, I have a quick question. Do you have to use DuplicateBuffer(), if you want to be playing a buffer from two different locations. Can you just do what you would do in directdraw with a surface:
  LPDIRECTDRAWSURFACE7 Surface1, Surface2; CreateSurface(Surface1); // Create the surface LoadImageIntoSurface(Surface1, "Something.bmp); // Fill it with data Surface2 = Surface1; // Have Surface2 point to Surface1 Surface1->AddRef(); // Add a reference to Surface1 
Well, I am pretty sure you have to use DuplicateBuffer(), but it seems quite slow so I want to make sure. Also, this doesn't pertain to DirectSound, but, is there any way to get a random number between 2 numbers. For instance, I want to get a number between 12 and 50. I have written a function to do this, but it is quite pimitive. Here is the source:
  int RandomIntBetween(int RangeLow, int RangeHigh) { int RandomNumber; // Random Number holder for(;;) { // Get a random number using 'RangeHigh' RandomNumber = rand() * (RangeHigh+1) / (RAND_MAX + 1); // If the random number is not between RaneLow //and RangeHigh, try again. if(RandomNumber >= RangeLow ) break; } return RandomNumber; }; 
Although it works, it has the potential to be very slow. If I were to try to get a random number between 50,000 and 51,000 it could take awhile. Well if anyone could help me with either of these two questions, I would definitely appreciate it. Thanks for your time. James Edited by - JSCFaith on October 30, 2001 10:31:04 PM

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Um, you could of course just do:

Get a random number between 0 and maximum-minimum

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Oh, I am suprised I never thought of that. Thanks for the help.

Thanks again,
James

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Oh, and if my understanding is correct, which it is not always... Duplicating DirectSound buffers will not duplicate the actual sound data in memory, just let seperate DSBuffer objects utilize the same region.

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What you describe in your code example is basically what DuplicateSoundBuffer is doing. It is leaving the data alone and just getting another pointer. However, with DirectSoundBuffer there is a lot of internal data relating to the sound playback (eg. A marker to indicate where in thebuffer it is currently playing). Just addreffing an DirectSoundBuffer instance will cause the instance specific data to be duplicated too and so the two sounds will not be able to be played independantly.

I have not experienced performance problems with DuplicateSoundBuffer, though. By definition it should be a fast call.

Cheers,
John

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