Re: [Discuss-gnuradio] initial gr-audio-portaudio

[Martin Dvh]

Stephane Fillod wrote:
> On Sun, Mar 12, 2006 at 02:36:21PM -0500, Robert McGwier wrote:
> 
>>That is why I put the message out.  It will be good to have a working 
>>starting point.
> 
> 
> Okay, there it is. Just checked in to gr-audio-portaudio repository.
> It's somewhat working, but there's still some static in the audio 
> output (tested with ALSA playback, mono and stereo). Some more work
> is needed.
> 
> You will need the attached patchs:
> 
> - against gnuradio-core: ot_gri_ringbuffer.patch
>       * src/lib/omnithread/omnithread.h: add omni_mutex::trylock
>       * src/lib/general/gri_ringbuffer.{cc,h},
>         src/lib/general/Makefile.am: new lockless ringbuffer (single
>           reader/single writer) taken from JACK software (GPL).
> 
> - against portaudio-V19(CVS): portaudio-pkg-config.patch
>       * pkg-config .pc file with proper THREAD_FLAGS
> 
> The code should be portable. I was missing the native Win32 call for
> mutex_trylock, so someone will have to find it, and define
> OMNI_MUTEX_TRYLOCK_IMPLEMENTATION in src/lib/omnithread/ot_nt.h,
> with appropriate semantic (return value).
I think you can do this with TryEnterCriticalSection
You could also use the omni_semaphore class defined in 
gnuradio-core/src/lib/omnithread/nt.cc
This latter one uses CreateSemaphore and WaitForSingleObject with some wrapper 
code.
(you probably have to change all defines if you change to using omni_semaphore)

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/tryentercriticalsection.asp
http://msdn.microsoft.com/library/en-us/dllproc/base/createsemaphore.asp?frame=true
http://msdn.microsoft.com/library/en-us/dllproc/base/waitforsingleobject.asp?frame=true

Another example of how it can be used (very much like our omni_semaphore class)
http://users.pandora.be/robert.deblier/beecrypt/mutex_8h-source.html

I don't have time to implement and test right now.
(I am working hard on finishing my gnuradio presentation for wednessday in 
Limburg)
If nobody implements it this week I will have a look next week.

greetings,
Martin
> The gri_pa_find_device_by_name() function will have to be made more
> smart, like accepting which HostApi (ALSA, JACK, ..) is to be chosen,
> and which device from this API. A syntax will have to be agreed upon,
> like "ALSA:hw:0" or "OSS:/dev/dsp1".
> 
> Have fun,