Solved

Playing real-time sound

Posted on 1997-11-26
5
223 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.
0
Comment
Question by:hakon
5 Comments
 
LVL 2

Expert Comment

by:anichini
ID: 1174184
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, ...])

0
 
LVL 2

Expert Comment

by:AlFa
ID: 1174185
Have you checked the DSCAPS (with GetCaps) of your device?

0
 

Author Comment

by:hakon
ID: 1174186
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.
0
 
LVL 23

Accepted Solution

by:
chensu earned 180 total points
ID: 1174187
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.
0
 

Author Comment

by:hakon
ID: 1174188
Thanks !
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Unlike C#, C++ doesn't have native support for sealing classes (so they cannot be sub-classed). At the cost of a virtual base class pointer it is possible to implement a pseudo sealing mechanism The trick is to virtually inherit from a base class…
Many modern programming languages support the concept of a property -- a class member that combines characteristics of both a data member and a method.  These are sometimes called "smart fields" because you can add logic that is applied automaticall…
The viewer will learn how to clear a vector as well as how to detect empty vectors in C++.
The viewer will be introduced to the technique of using vectors in C++. The video will cover how to define a vector, store values in the vector and retrieve data from the values stored in the vector.

919 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

21 Experts available now in Live!

Get 1:1 Help Now