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Re: [Discuss-gnuradio] GNURadio on Windows

From: Berndt Josef Wulf
Subject: Re: [Discuss-gnuradio] GNURadio on Windows
Date: Mon, 6 Feb 2006 15:12:09 +1030
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On Monday 06 February 2006 13:06, Robert McGwier wrote:
> Gerald Youngblood with Flex Radio has made a multimillion dollar
> business using V.19. He would be dead in the water without it being
> reliable.  I have used V.19 on windows, linux, etc.  I converted the
> gr-audio-alsa code to gr-audio-portaudio superficially and checked it
> in.  It will soon rise to the top of my plate.  I have used portaudio on
> top of jack for the new WJST development team.  Joe Taylor (K1JT for you
> hams) opened the source and invited a few to help.  He was using
> PortAudio V.19 on Windows.  I have been watching PortAudio closely now
> for almost two years.
> Recently:
> Eric Wachsmann of Flex Radio "finished" the windows code by getting
> portaudio to run reliably on top of Windows WDM-KS.   This was Flex
> Radio's pay back to that community for the value it has received.   This
> will be lower latency than linux-2.6 with low latency and alsa or jack
> in real time mode.  I know as I have measured it.  At this low level,
> Windows allow you to preempt the kernel and just about everything else
> almost without safe guards so you can get some truly tiny latencies.
> Arne Knudsen has steadily erased all problems I have experienced in
> using PortAudio on top of OSS, ALSA, and Jack.
> In the last month,  multiple people have gotten portaudio to run on
> Coreaudio and the Mac stuff is taking off.
> I would say that this is the single best hope we have for reliable and
> solid audio under Windows for GnuRadio.  I will soon return to this and
> help Eric, et. al. get it running and into the general cvs download and
> then all of us can beat it into shape.
> I might remind Berndt and everyone else that I have NEVER used a release
> version of GnuRadio.  They seem to stay current for about fifteen
> minutes under a major change was checked in!
> Bob
> Berndt Josef Wulf wrote:
> > On Monday 06 February 2006 11:04, Eric Blossom wrote:
> >> On Sun, Feb 05, 2006 at 09:12:10PM +0100, Martin Dvh wrote:
> >>>> Perhaps not enough buffering? Having source/sink in threads helps
> >>>> sometimes. Martin will have better insight on the topic.
> >>>
> >>> The code needs fixing but I haven't spend much time on optimizing it
> >>> yet. I think it does has something to do with threads. Maybe another
> >>> buffer layer or number of buffers (pingpong) will fix it. Put the
> >>> windows_audio sink in another thread will probably help, but I don't
> >>> know howto.
> >>>
> >>> I just copied the ideas for the windows_audio driver from other GPL'ed
> >>> windows audio projects.
> >>>
> >>> The windows_audio driver also needs an audio_source implementation.
> >>>
> >>> An other solution would be to implement a direct_audio driver (directX
> >>> audio) in stead of fixing this. I suspect you would have much less
> >>> synchronisation issues.
> >>>
> >>> A quick-and-dirty solution test would indeed be to increase the
> >>> audio-buffer. (You need to build from source to test this)
> >>>
> >>> An even more quick and dirty test is to change the default value for
> >>> all buffers between blocks. (Can be done after install)
> >>> change the value for self.fixed_buffer_size in
> >>> C:\Python24\site-packages\gnuradio\flow_graph.py line50:
> >>> self.fixed_buffer_size = 32*1024
> >>> Change this to a higher/lower value and see what it does for you.
> >>> The default is 32*1024 which means 32 kByte
> >>> Note that this value is for ALL blocks, so you might break things when
> >>> you make it too low and slow things down when you make it too high.
> >>>
> >>> greetings,
> >>> Martin
> >>
> >> I don't think changing the flow graph buffering is going to make any
> >> difference.  I think that the "right answer" is build a very
> >> high-functioning audio sink/source using portaudio.  It's on my list,
> >> but if somebody else wants to do it, please do (talk to me.  I've got
> >> some ideas.)  Using the portaudio CVS version 19 stuff, there is now
> >> good support for windows, and under ALSA and jack under Linux.  It's
> >> also supposed to work under OS/X using CoreAudio.
> >
> > There hasn't been any official releases since the 30 June 2003 with
> > V18.1. Do you think its a good idea to use the CVS version?
> >
> > No releases usually means an unacceptable status of the current work
> > unfit for public release.
> >
> > cheerio Berndt

Wow, many thanks for a very detailed report on portaudio. It has kindled my 
curiosity, so much so that I've downloaded and built the V19-devel snapshot.

It took only a few minor changes to get it going on NetBSD and sofar passed 
all test applications that I run in this short period of time. Will read the 
docs in greater details tonight.

cheerio Berndt

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