WAV file playtime stretching Logic / Algorithm / Source Code

[Bipin Mistry]

Hello all....
Please note that my current project is recording of audio conference.
I have been able to do so with some nasty coding..
But now am stuck up with audio Synchronization....
for eg...
Total Conference time is 10:00 mins
File play time for User A is 10:00 mins
File playtime for User B is 9:57 mins
File playtime for User C is 9:52 mins
Now when I mix all these files mixed file's play time will be 10:00
mins due to A's file is the longest play time.
BUT : B's Sound can be hared till 9:57 mins & so for C till 9:52
mins...

Now My Question...
I need some algorithm (Source Code / Logic which I can code) in VC++
such that I can do followings.
1. B's file can be stretched for 3 seconds to make it's play time as
10:00 mins
2. C's file can be stretched for 7 seconds to make it's play time as
10:00 mins

I have gone through many sample software's available on the net.. but
did not give me such accurate solution. (Most of them work with time
stretching in multiples of 10%)
More over I have worked with JITTER for the same at the recording
time... Didn't help much... JITTER usage has improved my output but
not as required.

Any one please do get back so as I can achieve this milestone as soon
as possible.

Thanks in advance..
Bipin

[Bob Cain]

Bipin Mistry wrote:

> Now My Question...
> I need some algorithm (Source Code / Logic which I can code) in VC++
> such that I can do followings.
> 1. B's file can be stretched for 3 seconds to make it's play time as
> 10:00 mins
> 2. C's file can be stretched for 7 seconds to make it's play time as
> 10:00 mins

Stephan Bernsee offers both free and higher function licensed libraries
(DLL's I suppose) for this purpose. He also has some free source code
but it is a tutorial implementation of the well known phase vocoder
approach rather than his far superior proprietary methods.

See:

http://dspdimension.com/

Bob
--

"Things should be described as simply as possible, but no simpler."

A. Einstein

[leutholl]

Hi,
Have you tried MPEX of Cubase?

For teh algorithm. I once implemented a time streching (well, tempo
shift or pitch shift maintaining the length) in C++. I didn't compared
with other algorithm which are propably better. I can have a look to
search for the code if you want - I think I should have it somewhere.
However this algorithm was performing realtime (on the input).

Lukas Leuthold

[Bipin Mistry]

Hi,

Will certenly like to have a look at source and get some tips as till
now we were trying to figure out other ways...
But diden't worked well.

Thanks
Bipin