Subject: Re: [linux-audio-dev] MTC, SMPTE, etc.
From: David Olofson (david_AT_gardena.net)
Date: Fri Jul 21 2000 - 18:51:34 EEST
On Thu, 20 Jul 2000, Paul Barton-Davis wrote:
> 4) Multi-port interfaces
> As far as I know, mostly a matter of getting specs. Given that
> MOTU, who make the most widely used MP MIDI interfaces, don't want
> to do this, its going to be hard to fix. I suspect that many
> other h/w makers take the same line.
Aaargh! Do we really *have* to build our own, just to get started...?
Oh, well. It could have been worse. MIDI interfaces are rather
trivial to design. (Compared to Hi-Fi and better audio cards, at
A simple workaround that will do for some is to build real simple
hardware (not as stupid as some consumer sound card MIDI interfaces,
though!) and use an RTL driver for the timing.
Another, even simpler solution would be to use hardware FIFOs
clocked at fixed rates, with the MIDI ports in parallel across the
FIFO words. The parallel/serial conversions are done by the driver.
That doesn't require RTL, but it may begin to eat CPU power. (The
output bit rate is 31250 bps, and the input needs to be an odd
multiple >1 of that, for bit sync and to deal with noise and bad
Is (input: sub) bit level timing accuracy good enough? ;-)
.- M u C o S --------------------------------. .- David Olofson ------.
| A Free/Open Multimedia | | Audio Hacker |
| Plugin and Integration Standard | | Linux Advocate |
`------------> http://www.linuxdj.com/mucos -' | Open Source Advocate |
.- A u d i a l i t y ------------------------. | Singer |
| Rock Solid Low Latency Signal Processing | | Songwriter |
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