[Ardour-Users] Ardour as a midi timecode slave

robertlazarski robertlazarski at gmail.com
Sun Apr 25 11:36:42 PDT 2021

On Sat, Apr 24, 2021 at 1:44 PM Paul Davis <paul at linuxaudiosystems.com>

> On Sat, Apr 24, 2021 at 5:16 PM robertlazarski <robertlazarski at gmail.com>
> wrote:
>> Two questions:
>> 1) Staying on topic, can I execute ardour stop / play commands with
>> system calls? Just curious what I can do.
> "system calls" is normally a term that describes what a program does it
> when needs to get some sort of the service from the operating system.
> I do not think that you mean that. I think you mean  using a terminal
> window and typing commands there.
> So your actual question is probably "can I send commands to ardour, from
> the command line, somehow?" The answer to that question: you can, using
> OSC. It's all described in at manual.ardour.org under "Control Surfaces".
> You will need a tool to send OSC commands ... "oscsend" is a common one.
Yes indeed. This command worked great:  oscsend osc.udp://localhost:3819

>> 2) Via a jltctrigger system call I need to send midi start / stop with
>> midi clock to an external sequencer that doesn't support MTC or MMC (Genoqs
>> Octopus). Google isn't showing much that is recent. Can you recommend the
>> right tool for the job?
> I don't think that there are any well known tools that will let you send
> an MIDI Song Position Pointer message (start and stop are not MIDI clock).
> THere are perhaps some low level tools that could write a few bytes to a
> MIDI port.You also do this in most scripting languages in a few lines.
> I hope you realize that sending start/stop will not provide
> synchronization between the sequencer and the LTC source: that would
> require continuous delivery of MIDI Clock messages, and they have
> absolutely nothing to do with LTC at all.
Thanks for the info. Some of my sequencers support SPP (Korg Oasys) and
some don't (Genoqs Octopus). They all require a continuous midi clock when
slaved in order to set the BPM.

My alternative to Linux and LTC is an expensive midi stomp pedal (Step
Audio Status + optional pedal is $400) that has a midi clock generator.
Yet's it not practical to get several of them for multiple devices.
Compared to my feet, anything would be a step up in timing tightness.

I already have an instrument switcher stomp pedal for my Oberkorn analog
sequencer as simply breaking the gate signal will suffice. I have midi
lighting plans. So I have outgrown pedals for performance control. I need
automation and already have LTC for my cameras.

Where Jack may be able to help me, is Bar:Beats:Ticks info (BBT). I found
jack_midi_clock that is a 700 line C project on github.

I am green on Linux audio. I don't have a midi interface yet so I am in the
proof of concept stage. I ran this command but nothing is happening -
jack_mclk_dump is in another shell. Connections look good in qjackctl.

/usr/local/bin/jack_midi_clock --bpm 120 jack_mclk_dump:mclk_in

I tried a few Linux sequencers: Rosegarden, after I enabled jack and midi
it only showed midi connections in the qjackctl alsa pane, not the midi
pane. So I couldn't connect jack_midi_clock to it. And seq24, I couldn't
get it to show anything in jack. I couldn't figure out how to sync
aplaymidi with midi clock.

Nevertheless, I am still encouraged by what jltctrigger and oscsend do as
the equivalent of that is what I was hoping to find in the nearly 40 year
history of LTC / midi hardware but never found it.

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