Re: [LAU] Roland A500S: snd-usb-audio error -5

On Sat, 28 Jan 2017 13:23:07 -1000, david wrote:
>My MIDI setup is too simple for me to notice any MIDI latency: one
>MIDI keyboard in via a simple MIDI->USB adaptor. No other hardware
>MIDI devices. Everything else is software.

The issue starts, if you expect to record and play MIDI with the same
timing quality you record an instrument by an audio track. IOW if
you don't quantise. It's also an issue if you quantise, but need perfect
sync, using external MIDI gear.

Linux DAW MIDI out ---------------------> External sampler HiHat MIDI in

External drum sampler HiHat audio out --> Linux DAW audio in

Record two audio tracks with the HiHat, not at the same time, but one
after the other. You'll hear audible jitter, if you play both audio
tracks in unison.

If you do the same with an Atari ST MIDI sequencer, SMPTE and a 4-track
tape deck or a C64 MIDI sequencer, click sync and a 4-track tape
deck, there's no audible jitter at all.

The speed of MIDI interfaces is only an issue, if you use one interface
for 16 MIDI channels, when using 4 individual interfaces for 16 MIDI
channels, you already could send short SysEx data quasi in real-time,
without experiencing issues. For modern computers jitter is an issue
and for old computers the sequencer's ticks-per-quarter-note is an
issue. Actually old sequencers with not enough ticks-per-quarter-note
are better, since the amount of jitter for modern computers renders the
more ticks-per-quarter-note useless.

Record a MIDI keyboard by an audio track and a MIDI track at the same
time with as much ticks-per-quarter-note as possible, don't quantise
the MIDI events, then play the MIDI and the audio track in unison. If
you hear a difference, it's jitter, not the speed limit of MIDI.

Regards,
Ralf
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Received on Sun Jan 29 12:15:01 2017