We help IT Professionals succeed at work.

Playing real-time sound

hakon
hakon asked
on
Medium Priority
258 Views
Last Modified: 2012-06-21
I'm working on a project, where I have to create sound in
real-time. The waveform is 8 bit PCM. I have tried to use
low level audio functions as described in DirectSound.

I'm using VC5.0++

When I'm playing a sound-sample I can hear some weak
noise as long as spesified.

I have used this functions:

DirectSoundCreate
SetCooperativeLevel
CreateSoundBuffer
Lock
memcpy
Unlock
SetCurrentPosition
Play

all of are returning "DS_OK", but the sound are not playing.

Please help.
Comment
Watch Question

Commented:
You might want to check to make sure the waveform data you are copying into the direct sound buffer is in the correct format and at the correct sampling rate. For example, 8 bit PCM is unsigned, so 128 is "zero". (So for example if you had a 22 khz, 8 bit buffer, a 11 khz square wave would be [255, 0, 255, 0, 255, ...])

Commented:
Have you checked the DSCAPS (with GetCaps) of your device?

Author

Commented:
Yes, I have checked the DSCAPS. Everything seems OK.

Now I'm using waveOut-functions. They are working, but I
hear a short silence between blocks of waveform data. I can
probably use this solution.
Commented:
Look into two samples that come with DirectX SDK: DSSHOW and DSSTREAM. And, you can use the functions in samples\misc\dsutil.c directly. Since you create the sound samples in real-time, you may use BOOL DSFillSoundBuffer(IDirectSoundBuffer *pDSB, BYTE *pbWaveData, DWORD cbWaveSize) function in dsutil.c.

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts

Author

Commented:
Thanks !
Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

OR

Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.