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Re: how to input sound directly from a audioplayer(like windows media player) into

Started by Jeff Brower January 30, 2011
Nangergong-
> sorry, there is one place which is wrong in the illustration. The latter computer
> is B not A.
>
> reference .wav file(signed 16bit, 8000Hz) ----> audio_player --------> VOIP program
> on computer A -----------> network ----------------> VOIP program on computer B
> ------------->audio recorder
> ------------------------------
>
> What is the point of the experiment? The data flow you describe above is a digital
>
> loopback -- by definition it's perfect, unless a) the "network" has packet loss
> (jitter), or b) you're using G729 or other codec over the network. If b), then
> suggest to download ITU G729 software (or other codec software) and use file
> operations.
> ---------------
> a) I did the test using LAN, and I used wireshark to capture the packets. I'm sure
> there is no packet loss, and the jitter is only several ms which is not a concern.
> The only problem is that the sound stream will be processed by hardware/driver
> before it goes into VOIP program.

Ok, so then use pre-recorded announcements so the VoIP program can read from file. I
guess you didn't see that suggestion.

-Jeff

PS. Post to the group, not to me.
> On Sun, Jan 30, 2011 at 6:34 AM, Jeff Brower wrote:
>
> Nangergong-
>
> > I want to do an experiment
> >
> > reference .wav file(signed 16bit, 8000Hz) ----> audio_player
> > --------> VOIP program on computer A -----------> network
> > ----------------> VOIP program on computer A
> > ------------->audio recorder
> >
> > when I use 'mixer' mode of recording device on Windows system
> > for transferring sound stream, the sound stream will be
> > processed by system hardware/drivers, which degrade PESQ a
> > lot,(frequency conversion, A/D, D/A conversion, background
> > noise, etc).
> >
> > I have found a piece of software named TotalRecorder for
> > recording, which can capture sound stream directly from VOIP
> > program without passing through system hardware/driver. However,
> > I havn't found any program/software which could input sound
> > stream directly from audio player to VOIP program.
> What is the point of the experiment? The data flow you describe above is
> a digital
> loopback -- by definition it's perfect, unless a) the "network" has
> packet loss
> (jitter), or b) you're using G729 or other codec over the network. If
> b), then
> suggest to download ITU G729 software (or other codec software) and use
> file
> operations.
>
> Another way to do this is use a VoIP program that can play recorded
> announcements.
> Then the program will either encode the .wav file as it reads it, or the
> program may
> required the file be preprocessed and stored in encoded format.
>
> -Jeff
>