Subject: Re: [linux-audio-dev] MTC, SMPTE, etc.
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: Thu Jul 20 2000 - 19:35:43 EEST
> I recently received an interesting letter from a studio owner who would
>like to switch to Linux. However, he was dismayed to find a real lack of
>Linux support for MIDI Time Code, SMPTE, multi-port interfaces, and so
>forth. This has him stopped in his tracks (apologies for the
>unintentionally bad pun).
I see there being several distinct issues.
1) MTC
This doesn't need much support in terms of raw code. MTC is pretty
easy to deal with. Ardour has source code for reading and sending
arbitrary MTC messages, but its so simple. The main issue is just
what timebase to use, and thats an app-dependent question.
2) SMPTE
This is more complex, but Takashi noted that Maarten gave him a
SMTPE decoder, which would be very nice to have as a library or
something.
3) Sync to MTC/SMPTE
Tricky. Very application dependent. I constantly worry about how
to do this, but I think this is just a particular concern of mine
that has no particular basis in reality.
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.
5) MIDI timestamping
Easy to do once the ALSA project agrees to do it. I would like
to see support for timestamped raw MIDI data, although I have
no concrete proposal on how to do this.
> With the recent attention paid to MidiShare, I wondered how MidiShare
>deals with these issues (particularly time code stuff). I also wondered
>how others on this list are affected by the lack of professional MIDI
>amenities.
>
> From my own POV, I'm disappointed that I can't use the advanced features
>of my nice dual-port MIDI interface (a Music Quest MQX32M). OSS/Linux
>supports the card, but apparently not completely. In fact, I don't think
>I've yet seen any Linux support for intelligent mode MIDI interfaces. Big
>bummer, since my studio gear is all MIDI-fied.
>
> I'm just rambling/rumbling here, but I'm interested in other opinions on
>the subject. Anyone want to add a peseta or two ??
Personally, I have avoided any intelligent MIDI interfaces, and stayed
with multiple cheap, single MIDI interfaces that talk to an external
h/w MIDI router. I have a unit that I've mentioned before, made by
MidiTemp, which is a true matrix router (any set of inputs to any set
of outputs). It cost me about $1000, imported from Germany. Thats what
we use in the studio anyway. Its fabulous, and it runs all the time
without any load or requirement that we have some OMS-like system
running on the studio computer.
At home, I have an older 15x16 non-matrix router from Ensoniq. That
one is totally packed full (or will be when my I-Cube arrives today!
yay!): FX unit(s), 3 external synths, an external Doepfer "analog"
sequencer, a DrumKAT, a PC1600x MIDI controller, etc. It can only
merge two ports at one time.
Both of these systems seem to allow me to do more or less everything
I've needed to so far. I have 2 (possibly 3 if I ran a cable from
inside the computer chassis) MIDI ports on my home system, and the
router lets them talk to any of my equipment without software
intervention. I haven't yet encountered a situation where I need more
than 2 ports/32 channels. Thats not to say that such a situation
cannot be imagined, its just a reflection of how I tend to work. If I
wanted to run more than 2 applications at the same time, I would have
a problem, but it seems that this might be true even of a 2 port
interface with ALSA support.
--p
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