The following was supposed to go to the list too.
Guenter
-----Original Message----- From: Miller Puckette [mailto:mpuckett@man104nfs.UCSD.EDU] Sent: Wednesday, March 24, 1999 6:29 PM To: pd-list@iem.mhsg.ac.at Subject: Audio drivers again?
Hi list,
I'm now running Pd under Red Hat Linux, and (like everybody else) I've run into some questions about audio/MIDI drivers. Would anyone already know the answers to these?
- I've got an OplSa3 soundcard and so far I've been using
the OSS drivers (the free ones from the RedHat 5.2 CDROM). I notice that the ADC noise floor (measured in the test tone patch) is around 45 dB, whereas the SAME HARDWARE gets a noise floor of 20 dB under NT. I've got a wild guess that this might be related to which of the two "DMA channels" I assign to "DMA0" and "DMA1"... any other wild guesses out there?
Hmmm .. if it is not a problem of the mixer settings, IŽd rather suspect something in the OplSa3 driver code. DMA0 and DMA1 are both 8 bit DMAŽs and they shouldnŽt do anything else but transfer the data to the card.
So it could be any open mixer channel "mic in", "line in" or "CD in", or prob. the relation between "wave out" and "master out" channels.
Or something in the driver code.
Do you get reliable full duplex with this card ? (Just asking cause I want to know which cards work)
- I also want to test the ALSA drivers. I note in the ALSA
FAQ (part of the release) that ALSA comes with an OSS compatibility package. So is there any advantage to using the ALSA drivers "natively" (as s_alsa.s does) rather than just using s_linux.c and having ALSA emulate OSS audio?
ALSAŽs OSS emulation simply doesnŽt work in full duplex (on my system at least). Seems it doesnŽt like the small audio buffer settings.
Anyhow, I never understood why they really changed the API instead of expanding it in a compatible way and wrapping their ALSA library around it.
- Same question for MIDI... is it likely to be worth the trouble of
rewriting the MIDI I/O code to address ALSA natively?
Together with WiniŽs MIDI library we can use the "raw midi device". This is supported the same way on OSS and ALSA. Its just opening the device file and reading or writing to it the MIDI bytes. Currently we donŽt support MIDI for accessing the internal sequencer (should we ?).
Guenter