Re: How to access soundcard in cygwin

[Igor Pechtchanski <pechtcha at cs dot nyu dot edu>]

Kaiduan,

Your mailer *still* doesn't respect the Reply-To: header.  When it's set
to the Cygwin list, this means that I'd like the reply to go to the Cygwin
list, not to me personally.  There is no need to Cc: me -- I read the
list.

To answer your question: sure it's possible to use Windows API in Cygwin
programs.  In fact, that's how Cygwin itself does it (see
winsup/cygwin/fhandler_dsp.cc in the Cygwin sources). :-)  Just beware of
API clashes (e.g., the C runtime functions provided by MSVCRT may clash
with that provided by the Cygwin DLL).
	Igor

On Wed, 7 Jan 2004, kaiduan xie wrote:

> Igor,
>
> What I am going to do is to port a Voice over IP client from Linux to
> Cygwin. It needs to read the voice sample from soundcard, encode it
> using some kind encoding algorithm, such as GSM, G.711, etc, and then
> send out to network in real time. At the same time, read the voice data
> packet from network, decode it and then write to soundcard. All
> operation should be real time. The voice sample to/from the soundcard is
> of 8-bit or 16-bit linear PCM.
>
> My question is, if Cygwin doesnot support that, can I use the native
> Windows API to do that? In other worlds, is it possible to use native
> Windows API in cygwin?
>
> Thanks.
>
> kaiduan
>  --- Igor Pechtchanski <pechtcha@cs.nyu.edu> wrote: >
> Kaiduan,
> >
> > Please make sure your mailer respects the Reply-To: header -- I set it
> > for a reason.  All discussion of Cygwin-related subjects should happen
> > on the Cygwin list unless specifically requested otherwise.  This
> > automatically makes it available to other people who care to look
> > (through the list archives), and (hopefully) helps reduce the traffic
> > on this list.
> >
> > Cygwin allows you to send any data to the soundcard by writing it to a
> > (device) file called '/dev/dsp'.  You can use the regular Unix
> > 'open()' and 'write()' system calls (or any other IO routines that
> > strike your fancy) to do this -- Cygwin will take care of sending the
> > data to the soundcard automatically.  The soundcard (or, rather, the
> > Windows soundcard driver) will recognize WAVE-formatted data.
> >
> > I believe the parameters you mentioned (frequency, duplex, etc) are
> > incorporated into the WAVE data format, but I'm not very familiar with
> > it, so it's best to double check.  Once you create a
> > suitably-formatted data, just write it to /dev/dsp.  There are plenty
> > of specifications of the WAVE format (.wav files) on the internet.
> >
> > Not knowing what the OSS API is, I'm unable to say whether Cygwin
> > supports it.  If all that's required is a /dev/dsp device file that
> > can be written to, then Cygwin has that.  I'm guessing the API is a
> > bit more than that, though.
> > 	Igor
> >
> > On Tue, 6 Jan 2004, kaiduan xie wrote:
> >
> > > Igor,
> > >
> > > Thanks for reply. So if cygwin doesnot have the API to read/write the
> > > soundcard, can I use the Windows API to read/write soundcard? All I need
> > > to do is opening the soundcard, setting the format (frequency, duplex
> > > mode, etc), and then reading from/writing to the soundcard.
> > >
> > > Any pointer?
> > >
> > > Thanks again.
> > >
> > > kaiduan
> > >
> > >  --- Igor Pechtchanski <pechtcha@cs.nyu.edu> wrote:
> > >
> > > On Tue, 6 Jan 2004, kaiduan xie wrote:
> > > >
> > > > > Hi, all,
> > > > >
> > > > > I am going to port a Linux program that read/write the soundcard
> > > > > with OSS driver to Cygwin. Can anyone tell me if it is possible to
> > > > > use the OSS API as in Linux to read/write the soundcard?
> > > >
> > > > Depends on what the OSS API does.  AFAIK, nobody released an OSS
> > > > (whatever that is) library for Cygwin, so I guess the answer is "no".
> > > > Whether it's possible to port the OSS library to Cygwin remains to be
> > > > seen...  FWIW, /dev/dsp *is* partially implemented in Cygwin.
> > > >
> > > > > If not, how to do that in Cygwin? Thanks.
> > > >
> > > > How to do what?  Access the soundcard?  Try 'cat a.wav > /dev/dsp' to
> > > > write to the soundcard.  AFAICS in the code, the 'read()' method is
> > > > dummied out, so I guess it's not possible to read from the soundcard
> > > > (i.e., record from the microphone).  This guess is confirmed by
> > > > <http://cygwin.com/ml/cygwin/2002-07/msg00628.html>.
> > > >
> > > > <http://cygwin.com/acronyms/#PTC>.
> > > >
> > > > You're welcome to try to add the recording (i.e., reading) support to
> > > > fhandler_dsp.cc in the Cygwin sources.  There was some discussion on
> > > > cygwin-patches that may point you in the right direction (notably
> > > > > <http://cygwin.com/ml/cygwin-patches/2002-q3/msg00112.html>).
> > > >
> > > > HTH,
> > > > 	Igor

-- 
				http://cs.nyu.edu/~pechtcha/
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