🚀 go-pugleaf

<ghislain.ruy@ieee.org> wrote in message news:3B48CDA3.CE2AAD36@ieee.org...
> Hello,

Hi Ghislane,

> does somebody know how to retrieve raw samples from a sound card in
> order to process them ?
> I had a look to winapi but it's quite cumbersome and I would prefer
> something like a linux driver (just read a file for example). Is there a
> dll to do the job ?

Unfortunately the driver model in Windows is significantly different to the
Linux one.  However, although the mmSystem API is a little complex it
doesn't take too long to work out.

Create a WAVEFORMATEX structure to describe the recording format you need
and pass it to waveInOpen() to open a wave input device.  Prepare two (or
more - two is a good starting number) buffers using waveInPrepareHeader(),
then add them to the record queue with waveInAddBuffer().  Start recording
with waveInStart().  Don't forget to allocate the memory for the buffers, as
the mmsystem won't do this for you.

Once that's all done you should get callbacks (or messages, or...) when each
buffer is filled.  Take the data out of the buffer and re-add the buffer to
the recording queue.  You might want to do this in a seperate thread to
abstract it all from your processing routines - use a memory stream or
something to store it in, then your processing routines just need to read
from the stream.

Once you are done recording, call waveInStop() to stop recording, wait for
the mmsystem to tell you it is done, then clean up: call
waveInUnprepareHeader() on all buffers prepared earlier, then waveInReset()
and finally waveInClose().

> Is it possible via the media player trough undocumented class members or
> so ?

I prefer to go straight to the mmsystem as it's about as low-level as you
can get without some knowledge of the actual sound drivers.  Of course you
could try using DirectSound... assuming it has a recording facility?  I
haven't touched DirectX yet, but then I haven't needed it.

> Thank you in advance for help.

Hope it helps.  Let me know if you get lost.

--
Corey Murtagh
The Electric Monk
"Quidquid latine dictum sit, altum viditur."

<ghislain.ruy@ieee.org> wrote in message news:3B48CDA3.CE2AAD36@ieee.org...
> Hello,
>
> does somebody know how to retrieve raw samples from a sound card in
> order to process them ?
> I had a look to winapi but it's quite cumbersome and I would prefer
> something like a linux driver (just read a file for example). Is there a
> dll to do the job ?
> Is it possible via the media player trough undocumented class members or
> so ?

Sorry about the delay replying... been messing around with news readers and
servers.

Anyway, there are two main ways to access the sound card: MMSystem and
DirectSound.  I prefer the first, because I've already got lots of code to
refer to.

Here's the basic sequence I use to record sound:

1: Prepare a WAVEFORMATEX struct to define the sample format
   (rate, bits, channels, etc)

2: Call waveInOpen() to open the input device

3: prepare a couple of WAVEHDR structs by allocating buffers,
   then calling waveInPrepareHeader() on both of them

4: Call waveInAddBuffer() to add both buffers to the record
   queue, then waveInStart() to start it running

5: message loop.  Wait on MM_WIM_DATA messages, process them
   (copy the data out of the buffer, then add it back into
   the queue with waveInAddBuffer)

6: when done, call waveInStop() and wait until all buffers
   have been returned

7: call waveInReset(), waveInUnprepareHeader() on both buffers,
   the waveInClose() to release the port.


Hope this helps.  I have some code I can send you if you get bogged down.


--
Corey Murtagh
The Electric Monk
"Quidquid latine dictum sit, altum viditur."

Would you happen to have any code to show a level meter even though the audio
driver doesn't include a meter I can read ??

ok, a little background:
I have a media player that will search for a meter (mixerGetLineControls) and
check for MIXERCONTROL_CONTROLTYPE_PEAKMETER on most controls, works great on
many different computers - except - for computers with audio drivers that don't
include any type of peak meters.
Do you know of anyway to get levels, without having to write a device driver ??
this realy bugs me!
Wally

Thank you very much.
I indeed took the time to dig into the windows API and finally got to
the sequence you suggests with success.
My primary job is RF & DSp electronic design, programming is a side
activity, but for one application, I needed to use the sound card
samples to process them.
I used a callback function instead of windows messages and got a
flawless class.
Thank you very much.

Corey Murtagh wrote:
> 
> <ghislain.ruy@ieee.org> wrote in message news:3B48CDA3.CE2AAD36@ieee.org...
> > Hello,
> >
> > does somebody know how to retrieve raw samples from a sound card in
> > order to process them ?
> > I had a look to winapi but it's quite cumbersome and I would prefer
> > something like a linux driver (just read a file for example). Is there a
> > dll to do the job ?
> > Is it possible via the media player trough undocumented class members or
> > so ?
> 
> Sorry about the delay replying... been messing around with news readers and
> servers.
> 
> Anyway, there are two main ways to access the sound card: MMSystem and
> DirectSound.  I prefer the first, because I've already got lots of code to
> refer to.
> 
> Here's the basic sequence I use to record sound:
> 
> 1: Prepare a WAVEFORMATEX struct to define the sample format
>    (rate, bits, channels, etc)
> 
> 2: Call waveInOpen() to open the input device
> 
> 3: prepare a couple of WAVEHDR structs by allocating buffers,
>    then calling waveInPrepareHeader() on both of them
> 
> 4: Call waveInAddBuffer() to add both buffers to the record
>    queue, then waveInStart() to start it running
> 
> 5: message loop.  Wait on MM_WIM_DATA messages, process them
>    (copy the data out of the buffer, then add it back into
>    the queue with waveInAddBuffer)
> 
> 6: when done, call waveInStop() and wait until all buffers
>    have been returned
> 
> 7: call waveInReset(), waveInUnprepareHeader() on both buffers,
>    the waveInClose() to release the port.
> 
> Hope this helps.  I have some code I can send you if you get bogged down.
> 
> --
> Corey Murtagh
> The Electric Monk
> "Quidquid latine dictum sit, altum viditur."

-- 
--------------
Ghislain RUY
F1HDD
AMSAT FRANCE
Chef de projet SATEDU
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