extracting data from sound card

+re: +c++ +capturebuffer -c#

Hello there, I am doing a project titled Heartbeat Monitor. The sensors used to detect the EGG signal were electrode pads. I was planning to cut cost and use the microphone jack as an interface between my circuit and the computer. I read somewhere that the sound card could be used as an ADC and after extracting this data using Visual Basic a program is written in Visual Basic to count the number of heartbeats. My question is how do I convert the analogue data to digital using the sound card and how do I call the digitised signal and then count it? I am only familiar with the basics of C++ and I have yet to learn how to create a GUI with VB. Thank you for any input.

interfacing sound card vb

The easiest way is to use DirectX -> DirectSound -> CaptureBuffer.

Basically you create an interface to DirectX, open DirectSound, create the CaptureBuffer, start it and read from it.

You could also look at OpenAL, I think it is a C Library/API that is fairly simple to use.

sound card adc read visual basic

In order to do this I first need the audio API right ... Since I am going to use the soundcard as the ADC (feed the ECG mono signal through the microphone jack socket) which API do I need?

I am going to use the ECG signal to calculate the number of heartbeats and display it on a VB made oscilloscope. Does anyone knows the bunch of API that I need? I found some on the internet, but I doubt I need them all. Help please and thank you to those who replied.

Hello again,

I have found a software done by someone that meets my requirements where he provided the codes and EXE files that can be downloaded here . More information on his software can be found here.

I am using his codes for reference in building my own software. However when I went through "Functions.bas" I saw the following APIs and multimedia functions:

1. waveOutStart
2. WaveOutStop
3. WaveOutAddBuffer
4. mmioDescendParent
5. mmioReadFormat

I tried looking through Microsoft's MSDN website, but could not find anything on them. The EXE file that the programmer compiled works just fine, so I am wondering what those three APIs and two multimedia functions are for since I could not find anything on the internet. Thank you to those who replied.

Have you tried: http://www.portaudio.com/?

Works well and works on Windows, Linux, etc.

If you have access to Nuts & Volts, I did an article that used portaudio a few years back.

Ah thank you for the site. Anyway as I want to plot my ECG signal, how do I do that? From the codes the x and y coordinates were calculated. I am rather lost with the codes and how the programmer calculate x and y. Anyone?