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How to capture voice input?

Posted on 2000-03-03
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Last Modified: 2010-04-10
I am writing a Visual C++ program that have to capture the time whenever there is a voice input towards the microphone. I have no idea how to work it out as I am a novice towards multimedia programming. Please help, it is very urgent.
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Question by:LiWangOn
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Expert Comment

by:Wyn
ID: 2582552
Qed...
1. MCIWnd Window Class

Recording with MCIWnd Controls
http://msdn.microsoft.com/library/psdk/multimed/mciwnd_0e43.htm 

2. MCI

Recording with a Waveform-Audio Device
http://msdn.microsoft.com/library/psdk/multimed/mci_4wpx.htm 

3. Waveform Audio

Example of Writing Waveform Data
http://msdn.microsoft.com/library/psdk/multimed/wave_8rj5.htm 

Recording and Playing Waveform Audio
http://msdn.microsoft.com/library/techart/msdn_spellit.htm 

4. DirectSound

Tutorial 2: Capturing a Sound
http://msdn.microsoft.com/library/psdk/directx/dstut_9ox0.htm
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Author Comment

by:LiWangOn
ID: 2582631
Thx for the reply, but that's not what exactly I want to do. What I want to do is to know when there is a voice input towards the microphone so that I could ask the program to progress on other activity.
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Expert Comment

by:Wyn
ID: 2583271
->What I want to do is to know when there is a voice input towards the microphone so that I could ask the program to progress on other activity.
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hmm...I think the answer is what you want.plz check it and You will find the answer there.
Anyway,good luck.
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Author Comment

by:LiWangOn
ID: 2584241
I think I get your point. You mean I should analyze the data in the buffer while capturing the sound?

But I still confuse that how could I know which sample is having the "voice", and how to know the corresponding time of that sample?

(Actually I am writing a program to get respond time)
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Author Comment

by:LiWangOn
ID: 2584978
I want to get the time difference (in ms) between a word presented on the computer screen and the user's respond towards the microphone.
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Accepted Solution

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bkdc earned 100 total points
ID: 2682153
1. open the wave device with waveInOpen
with let's say callback function
2. create some buffers (one might be enough) of 1/2 (or other period) seconds.
3. get and store the system time - GetSysteTime (or use a timer) and then call waveInStart
4. when a buffer is recorded your callback function will be called (obvious that 1/2 sec elapsed)
5. any buffer will have some values in it differing from 0 (background noise).
If it's noise then it's usually in a narrow range (for example my sb./mic. generates noise between  -800 till -580
If the samples are not in this range then it's voice.
6. calculate the exact time when voice starts (using the sample index in the buffer and the sampling frequency)

7. of course you must have the time when the word was shown on the monitor

8. a simple substraction should give you the answer


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