Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!psuvax1!gatech!unmvax!bbx!bbxsda!scott
From: scott@bbxsda.UUCP (Scott Amspoker)
Newsgroups: comp.music
Subject: Re: Need help With MIDI interface S/W Ideas.
Keywords: Keyboard to IBM via MIDI.
Message-ID: <288@bbxsda.UUCP>
Date: 23 Oct 89 18:18:22 GMT
References: <2211@servax0.essex.ac.uk> <18642@pasteur.Berkeley.EDU>
Reply-To: scott@bbxsda.UUCP (Scott Amspoker)
Organization: Basis International,  Albuquerque, NM
Lines: 44

In article <18642@pasteur.Berkeley.EDU> maverick@oak.Berkeley.EDU (Vance Maverick) writes:
>[about designing a sequencer]
>For notes I recommend a structure like this:
>
>typedef struct {
>        long time;              /* Attack time from start of track */
>        unsigned int length;    /* Length in same time units */
>        char pitch,             /* MIDI information: pitch 0-127 */
>            channel,            /* channel 0-15 (low nibble of status) */
>            velocity,           /* Attack velocity (from note-on) */
>            release;            /* Release velocity (from note-off) */
>    } note;
>
>(Assuming long = 32 bits, int = 16, char = 8.)
>
>In writing a MIDI sequencer three years ago, my partner and I committed
>ourselves early on to a track format where ons and offs were stored
>separately.  This became a real pain when we started implementing edit
>operations.

Good advice!  I "discovered" that myself after getting halfway through
the project.  It was significant enough to warrant rewriting a lot
of code.  It gets a little trickier during record and playback but
makes a lot of other features a lot easier.

>For timing on the PC, there are a couple of options.  The Roland MPU
>interface and its clones will do timing for you, in 120ths of a quarter
>note (and other resolutions);  this is quite adequate for a sequencer.

This is not a flame but I'm not entirely sure that 120 ppq is enough.
I use 480 ppq and admit that it might be an overkill but I do a lot
of "free-form" sequencing (without a click).  When I do use a click
and drum machine I almost never quantize except maybe the bass part.
Since I use a Yamaha C1 I don't know much about the Roland MPU.  The
C1 provides an additional interval timer for applications.  There
are 2 input and 8 output ports that contain on-chip FIFOs (about 16
bytes) so the main application is not overburdened with interrrupt 
handling.

-- 
Scott Amspoker
Basis International, Albuquerque, NM
(505) 345-5232
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