Subject: [linux-audio-user] Re: [Alsa-devel] Re: HDSP 9652 MIDI - A timing disaster?
From: Mark Knecht (markknecht_AT_attbi.com)
Date: Tue Jan 14 2003 - 07:16:05 EET
On Mon, 2003-01-13 at 09:04, Clemens Ladisch wrote:
> Mark Knecht wrote:
> > I recently purchased an RME HDSP 9652 card. The card is working fine
> > for audio, but the MIDI interface is a timing disaster. The interface
> > works, but won't keep time. A 2 minute song is Rosegarden takes abut
> > 2:45 to play every time. You can hear how the HDSP isn't delivering
> > closely spaced MIDI events together, but is sort of smearing them out.
>
> The hdsp driver doesn't send more than one MIDI byte per timer tick.
> IMHO it should be modified to send in a loop until the FIFO is full
> (however, I don't know if the HDSP has a FIFO at all). And it should start
> sending in output_trigger() instead of delaying it to the next timer tick.
>
Clemens,
Thanks for the response. One comment I forgot to make in the first
post. This MIDI interface works fine under Windows, so whatever causes
the problem is purely a Alsa MIDI issue. If we can figure it out, then
we can fix it.
I agree that it sounds like this sort of one note per timer tick.
When the interface is supposed to send a chord, it sends what sounds
like an arpegiated chord. It's all smeared out.
Is there some example code I could look at to understand implementing
a FIFO? However, if there is a FIFO Full indication, doesn't we need to
know _how_ it's indicated? I would assume it's different for all cards?
(Bus possibly similar for cards from the same manufacturer?
Also, this is the HDSP 9652, which is a single PCI card. Is this
problem showing up for the DigiFace/MultiFace type cards?
Thanks,
Mark
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