Full-duplex questions

Michael Lechasseur mlecha at music.mcgill.ca
Mon Dec 21 14:45:05 CET 1998

    Is there a simple way to test for a driver's full-duplex capabilities
outside of pd?  I've tried mixing several inputs sources such as line-in, cd
audio in, and playing an mp3, which can all heard via the sound cards
output.  This suggests to me that my sound card and drivers are full-duplex
capable outside of pd.  Or is this a naive assumption?

    The doc's for OSS/Free suggest that these drivers are half-duplex only.
I didn't actually try it outside of pd before I bought the commercial
drivers.  Are you getting full-duplex audio outside of pd using OSS/Free?

>2) Didn4t try OSS/Linux, because it crashed my computer (alpha)
>   the last time I installed it. You could try setting the audiobuffer
>   size and look if it works ..

    I am unfamiliar with the audiobuffer size parameter.  Do I want to set
this for the driver or loading pd?

>1) with OSS/Free, the card only works in full duplex with BIG
>   audiobuffer sizes.(kernel 2.1.131)

    Same question.  How do you set the audiobuffer?

>In my opinion the OSS driver just don4t work as documented, or rather, the
>documentation lacks a specification of minimum audiobuffer sizes.

    I have found the OSS email tech support to be excellent and really fast.
Which is why I paid for the commercial drivers.  Why don't you get in touch
with them?

>3) After trying ALSA I realized, that the ALSA code in pd is only
>   full duplex with two soundcards. Then, I4m having problems with ALSA
>   Alpha anyway, which I have to investigate further.

    Hey, I still have my old SB16.  Maybe I can use that as an input device
and use my PCI128 as output.  I doubt that win95 would like that
configuration, but ALSA supports it.  Thanks for the idea.

    I found that the ALSA drivers sounded better than the OSS ones, but have
no testing gear to prove it.

>until then (early Jan), you could only look into s_linux.c and try to fix
>OSS code yourself..

    ha!  I have the ambition, but I doubt the technical knowledge yet.
There are people in the know here at school though.  Maybe between I can
convince them to give a hand for a good cause.

>Merry Christmas

    Same to you!

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