I tried to post this already, but I think it failed.
I am looking to do a simple telephony project at home. I'm using WIN32 (C++) SDK Tapi 3 (in visual studio 2008 on XP SP3), and I would like to make the microphone and speakers from my soundcard work as a speakerphone. Sometimes, accidentally, I get the sound coming out of my speakers, but I didn't exactly do it on purpose... Does anyone know of a simple tutorial for this kind of thing? I would also like the capability to record telephone calls. From what I understand, I have to create rendering and capturing terminals and select them onto my stream. I think I'm succeeding at that (and all the stuff before that: getting an address, basic call, et cetera), but when I actually attempt to make a call, it silently fails. I call the dial method and connect method, and I can't tell that anything happens, the methods return immediately and nothing comes out my speakers. I think the return is S_OK. I'm pretty sure I have Full Duplex (or whatever it's called) functionality on my soundcard (I'm able to record and playback at the same time). Let me know if you would like a minimal source code example of what I'm doing (which would basically be the whole project). Again, feel free to point me to existing material. Thanks in advance.
> I am looking to do a simple telephony project at home. I'm using > WIN32 (C++) SDK Tapi 3 (in visual studio 2008 on XP SP3), and I would > like to make the microphone and speakers from my soundcard work as a > speakerphone. Sometimes, accidentally, I get the sound coming out of > my speakers, but I didn't exactly do it on purpose... Does anyone > know of a simple tutorial for this kind of thing? > I would also like the capability to record telephone calls. From > what I understand, I have to create rendering and capturing terminals > and select them onto my stream. I think I'm succeeding at that (and > all the stuff before that: getting an address, basic call, et cetera), > but when I actually attempt to make a call, it silently fails. I call > the dial method and connect method, and I can't tell that anything > happens, the methods return immediately and nothing comes out my > speakers. I think the return is S_OK. I'm pretty sure I have Full > Duplex (or whatever it's called) functionality on my soundcard (I'm > able to record and playback at the same time).
-- Best Regards Andreas Marschall Microsoft MVP for TAPI / Windows SDK / Visual C++ 2003-2008 TAPI / TSP Developer and Tester My TAPI and TSPI FAQ: http://www.I-B-A-M.de/Andreas_Marschall's_TAPI_and_TSPI_FAQ.htm My Toto® Tools (a collection of free, mostly TAPI related tools): http://www.i-b-a-m.de/Andreas_Marschall's_Toto_Tools.htm TAPI development around the world (Frappr! map): http://www.frappr.com/TAPIaroundTheWorld * Please post all messages and replies to the newsgroup so all may * benefit from the discussion. Private mail is usually not replied to. * This posting is provided "AS IS" with no warranties, and confers no rights.
This is copied from my sent mail...I thought I sent it Thursday or Friday. I'm using the modem that came with my computer. I suppose it's a voice modem; is there some reason why I ought to suspect it's not. I know it also handles faxes. Perhaps I need to investigate this. What other types might it be and how can I identify mine? I use a Dell ... Inspiron err...ellipse err.. not optiplex...whatever, one of those popular Dell desktops with the factory modem. I look forward to hearing back from someone. In my original post, I think I answered the part about full-duplex:
>I'm pretty sure I have Full > Duplex (or whatever it's called) functionality on my soundcard (I'm > able to record and playback at the same time)."
Perhaps you're reminding me to be absolutely sure about that -- I'll check it tonight or soon, thank you. Thanks again for your help.
In Christ, Aaron Laws
On Oct 1, 2:29 pm, "Andreas Marschall [exMVP TAPI]"
> -- > Best Regards > Andreas Marschall > Microsoft MVP for TAPI / Windows SDK / Visual C++ 2003-2008 > TAPI / TSP Developer and Tester > My TAPI and TSPI FAQ:http://www.I-B-A-M.de/Andreas_Marschall's_TAPI_and_TSPI_FAQ.htm > My Toto® Tools (a collection of free, mostly TAPI related tools):http://www.i-b-a-m.de/Andreas_Marschall's_Toto_Tools.htm > TAPI development around the world (Frappr! map):http://www.frappr.com/TAPIaroundTheWorld > * Please post all messages and replies to the newsgroup so all may > * benefit from the discussion. Private mail is usually not replied to. > * This posting is provided "AS IS" with no warranties, and confers no > rights.
> I'm using the modem that came with my computer. I suppose > it's a voice modem; is there some reason why I ought to suspect it's > not. I know it also handles faxes. Perhaps I need to investigate > this. What other types might it be and how can I identify mine?
Aaron, those built-in modems are often only fax/data modems. You can check whether it has DeviceClasses "wave/in" and wave/out" in LINEDEVCAPS / LIONEADDRESSCAPS.
> In my original post, I think I answered the part about full-duplex: > >I'm pretty sure I have Full > > Duplex (or whatever it's called) functionality on my soundcard (I'm > > able to record and playback at the same time)." > Perhaps you're reminding me to be absolutely sure about that -- I'll > check it tonight or soon, thank you.
My point wasn't the duplex capabilties of your soundcard but of your modem...
> Thanks again for your help.
You are welcome.
-- Best Regards Andreas Marschall Microsoft MVP for TAPI / Windows SDK / Visual C++ 2003-2008 TAPI / TSP Developer and Tester My TAPI and TSPI FAQ: http://www.I-B-A-M.de/Andreas_Marschall's_TAPI_and_TSPI_FAQ.htm My Toto® Tools (a collection of free, mostly TAPI related tools): http://www.i-b-a-m.de/Andreas_Marschall's_Toto_Tools.htm TAPI development around the world (Frappr! map): http://www.frappr.com/TAPIaroundTheWorld * Please post all messages and replies to the newsgroup so all may * benefit from the discussion. Private mail is usually not replied to. * This posting is provided "AS IS" with no warranties, and confers no rights.
Thank you very much for your expertise. I will check further soon. It seems that a fax modem ought to be able to do everything a voice modem can do. If the modem can play the analog sound it hears coming from the phone line, and it can transmit an analog singal, why can't it take that signal from the sound card, or my program for that matter? Perhaps I could write a program imitating a fax machine such that after the phone rings four or six times, my program can translate wav data into 'fax' data (whatever transformation that would be...) then play a beep, then begin recording the incoming 'fax' (caller's voice)? Thanks again, and I'll check soon about what you told me to check.
In Christ, Aaron Laws
On Oct 5, 5:06 pm, "Andreas Marschall [exMVP TAPI]"
<Andreas.Marsch...@I-B-A-M.de> wrote: > Aaron, > those built-in modems are often only fax/data modems. > You can check whether it has DeviceClasses "wave/in" and wave/out" in > LINEDEVCAPS / LIONEADDRESSCAPS.
> My point wasn't the duplex capabilties of your soundcard but of your > modem...
> You are welcome.
> -- > Best Regards > Andreas Marschall > Microsoft MVP for TAPI / Windows SDK / Visual C++ 2003-2008 > TAPI / TSP Developer and Tester > My TAPI and TSPI FAQ:http://www.I-B-A-M.de/Andreas_Marschall's_TAPI_and_TSPI_FAQ.htm > My Toto® Tools (a collection of free, mostly TAPI related tools):http://www.i-b-a-m.de/Andreas_Marschall's_Toto_Tools.htm > TAPI development around the world (Frappr! map):http://www.frappr.com/TAPIaroundTheWorld > * Please post all messages and replies to the newsgroup so all may > * benefit from the discussion. Private mail is usually not replied to. > * This posting is provided "AS IS" with no warranties, and confers no > rights.
> Thank you very much for your expertise. I will check further soon. > It seems that a fax modem ought to be able to do everything a voice > modem can do. If the modem can play the analog sound it hears coming > from the phone line, and it can transmit an analog singal, why can't > it take that signal from the sound card, or my program for that > matter?
No, it can't! Fax transmission as well as data transmission is handled by DSPs in the hardware of modems. You never get at the "raw" data. The raw data is actually analog audio (as it is an analog phone line), which is running through different filters and is then digitized and processed by the TSP. Then the actual fax page bits are sent to the computer.
For analog audio different filtering and AD conversion has to be performed. Either a modem has implemented this in its hardware or not!
> Perhaps I could write a program imitating a fax machine such > that after the phone rings four or six times, my program can translate > wav data into 'fax' data (whatever transformation that would be...) > then play a beep, then begin recording the incoming 'fax' (caller's > voice)?
No...
Best regards,
Matthias Moetje ------------------------------------- TAPI WIKI: http://www.tapi.info ------------------------------------- TERASENS GmbH Augustenstraße 24 80333 Munich, GERMANY ------------------------------------- e-mail: moetje at terasens dot com www: www.terasens.com -------------------------------------
If you don't feel like answering this, don't bother, but I'm wondering about the history of this. If I were creating this (and I AM a novice), I would make it such that the data would come in to the modem (analog, of course), and the modem would convert it to digital (AD at the sample rate specified by the program, or TAPI, but perhaps ultimately by the program) and send it on. Then, the program (either fax or other) would take care of those bits. This 'taking care of' could be done by a service of the windows 32 framework (TAPI, for instance), then the program can get the info, either translating as audio or fax, or a custom use (whatever that might be). What is the advantage of hiding the data from the programmer and putting more work on the modem side where parameters can't be specified? Or perhaps here my ignorance betrays me here with `where parameters can't be specified.' Do modems have a standard sample rate? I am now beginning to see why there might be a Most Valuable Professional in this field: because of the obtuse nature of phone-line/ computer interchange. At first blush, I thought it would be a simple thing, just standard audio manipulation, and if I wanted to create a fax machine, I would not treat those digital samples as audio samples, but as data bits. Oh well. Thanks again for your time.
> > Thank you very much for your expertise. I will check further soon. > > It seems that a fax modem ought to be able to do everything a voice > > modem can do. If the modem can play the analog sound it hears coming > > from the phone line, and it can transmit an analog singal, why can't > > it take that signal from the sound card, or my program for that > > matter?
> No, it can't! Fax transmission as well as data transmission is handled > by DSPs in the hardware of modems. You never get at the "raw" data. > The raw data is actually analog audio (as it is an analog phone line), > which is running through different filters and is then digitized and > processed > by the TSP. Then the actual fax page bits are sent to the computer.
> For analog audio different filtering and AD conversion has to be performed. > Either a modem has implemented this in its hardware or not!
> > Perhaps I could write a program imitating a fax machine such > > that after the phone rings four or six times, my program can translate > > wav data into 'fax' data (whatever transformation that would be...) > > then play a beep, then begin recording the incoming 'fax' (caller's > > voice)?
Older computers simply were not fast enough to perform the required signal processing. Therefore this was done in DSPs. DSPs are highly specialiced processors, not suitable to drive a computer but able to perform certain signal processing tasks much faster than a usual CPU.
In these times everything was done to save the CPU processing power for other tasks. Additionally through their multitasking implementations the operating systems were not able to guarantee a permanent stream of realtime processing. Another process could "steal" CPU cycles and this could cause the data stream on the phone line to interrupt.
Similar things apply to audio cards or graphic cards.
Recently PC designs were introduced that in fact use the processor to perform such things. There are audioc codecs (like AC97) and also modem codecs where the processing is done by the CPU. But even in these cases this is handled by some components on the chipset but not by software in the OS.
One more thing: Data transmission over analog lines is not as simple as digitizing the data like with consumer audio. There is much more to it as a frequency multiplex is used and complex algorithms are used to MOdulate and DEModulate.
If you really would be presented with a digitized stream of the audio, you would never be able to get the real data out of it. Additionally this is a duplex operation: One modem must respond reception or misreception instantly. There is not enogh time as that this could be done reliably through a process running in user mode.
Best regards,
Matthias Moetje ------------------------------------- TAPI WIKI: http://www.tapi.info ------------------------------------- TERASENS GmbH Augustenstraße 24 80333 Munich, GERMANY ------------------------------------- e-mail: moetje at terasens dot com www: www.terasens.com -------------------------------------
"Limited_Atonement" <dartm...@gmail.com> wrote in message
> If you don't feel like answering this, don't bother, but I'm > wondering about the history of this. If I were creating this (and I > AM a novice), I would make it such that the data would come in to the > modem (analog, of course), and the modem would convert it to digital > (AD at the sample rate specified by the program, or TAPI, but perhaps > ultimately by the program) and send it on. Then, the program (either > fax or other) would take care of those bits. This 'taking care of' > could be done by a service of the windows 32 framework (TAPI, for > instance), then the program can get the info, either translating as > audio or fax, or a custom use (whatever that might be). > What is the advantage of hiding the data from the programmer and > putting more work on the modem side where parameters can't be > specified? Or perhaps here my ignorance betrays me here with `where > parameters can't be specified.' Do modems have a standard sample > rate? I am now beginning to see why there might be a Most Valuable > Professional in this field: because of the obtuse nature of phone-line/ > computer interchange. At first blush, I thought it would be a simple > thing, just standard audio manipulation, and if I wanted to create a > fax machine, I would not treat those digital samples as audio samples, > but as data bits. Oh well. Thanks again for your time.
> In Christ, > Aaron Laws
> On Oct 8, 8:20 pm, "Matthias Moetje [exMVP]" > <moetje@terasens_nospam_.de> wrote: >> Aaron,
>> > Thank you very much for your expertise. I will check further soon. >> > It seems that a fax modem ought to be able to do everything a voice >> > modem can do. If the modem can play the analog sound it hears coming >> > from the phone line, and it can transmit an analog singal, why can't >> > it take that signal from the sound card, or my program for that >> > matter?
>> No, it can't! Fax transmission as well as data transmission is handled >> by DSPs in the hardware of modems. You never get at the "raw" data. >> The raw data is actually analog audio (as it is an analog phone line), >> which is running through different filters and is then digitized and >> processed >> by the TSP. Then the actual fax page bits are sent to the computer.
>> For analog audio different filtering and AD conversion has to be >> performed. >> Either a modem has implemented this in its hardware or not!
>> > Perhaps I could write a program imitating a fax machine such >> > that after the phone rings four or six times, my program can translate >> > wav data into 'fax' data (whatever transformation that would be...) >> > then play a beep, then begin recording the incoming 'fax' (caller's >> > voice)?
Your expertise is appreciated. Thanks again for allowing yourself to be publically questioned, day after day. Do you or the other guru here get paid for spending SO MUCH time answering newbie questions? I bow before your experience!!
> Older computers simply were not fast enough to perform > the required signal processing. Therefore this was done > in DSPs. DSPs are highly specialiced processors, not > suitable to drive a computer but able to perform certain > signal processing tasks much faster than a usual CPU.
> In these times everything was done to save the CPU > processing power for other tasks. Additionally through > their multitasking implementations the operating systems > were not able to guarantee a permanent stream of realtime > processing. Another process could "steal" CPU cycles and > this could cause the data stream on the phone line to interrupt.
> Similar things apply to audio cards or graphic cards.
> Recently PC designs were introduced that in fact use the processor > to perform such things. There are audioc codecs (like AC97) > and also modem codecs where the processing is done by the > CPU. But even in these cases this is handled by some components > on the chipset but not by software in the OS.
> One more thing: Data transmission over analog lines is not > as simple as digitizing the data like with consumer audio. There > is much more to it as a frequency multiplex is used and complex > algorithms are used to MOdulate and DEModulate.
> If you really would be presented with a digitized stream of the > audio, you would never be able to get the real data out of it. > Additionally this is a duplex operation: One modem must respond > reception or misreception instantly. There is not enogh time > as that this could be done reliably through a process running > in user mode.
> Your expertise is appreciated. Thanks again for allowing yourself > to be publically questioned, day after day. Do you or the other guru > here get paid for spending SO MUCH time answering newbie questions? I > bow before your experience!!
> In Christ, > Aaron Laws
> On Oct 16, 4:28 pm, "Matthias Moetje [exMVP]" > <moetje@terasens_nospam_.de> wrote: >> Aaron,
>> the history behind this is as follows:
>> Older computers simply were not fast enough to perform >> the required signal processing. Therefore this was done >> in DSPs. DSPs are highly specialiced processors, not >> suitable to drive a computer but able to perform certain >> signal processing tasks much faster than a usual CPU.
>> In these times everything was done to save the CPU >> processing power for other tasks. Additionally through >> their multitasking implementations the operating systems >> were not able to guarantee a permanent stream of realtime >> processing. Another process could "steal" CPU cycles and >> this could cause the data stream on the phone line to interrupt.
>> Similar things apply to audio cards or graphic cards.
>> Recently PC designs were introduced that in fact use the processor >> to perform such things. There are audioc codecs (like AC97) >> and also modem codecs where the processing is done by the >> CPU. But even in these cases this is handled by some components >> on the chipset but not by software in the OS.
>> One more thing: Data transmission over analog lines is not >> as simple as digitizing the data like with consumer audio. There >> is much more to it as a frequency multiplex is used and complex >> algorithms are used to MOdulate and DEModulate.
>> If you really would be presented with a digitized stream of the >> audio, you would never be able to get the real data out of it. >> Additionally this is a duplex operation: One modem must respond >> reception or misreception instantly. There is not enogh time >> as that this could be done reliably through a process running >> in user mode.
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