Dummy backend disappeared?


It seems that since a few versions (1 month?), the ‘dummy’ backend has disappeared.

Before that, I could choose between alsa, jack, or dummy.

But now, dummy doesn’t show up, even if enabled at compilation.

The same thing goes for the daily builds.
It seems that the dummy backend is enabled, according to the build logs.
But ‘dummy’ is not present in the combo box

Yes, there are some changes since 5.4 (74ba1b26 and 842c33fb) that mean the dummy backend is only added to the list of available backends if you are either building and running Ardour from the source tree or you have “hide-dummy-backend” = “0” in the config file (~/.config/ardour/config on linux)

If you think this is an issue for some reason please file a report in the bug tracker.

The dummy backend’s main purpose is debugging and it is supposed to be only available with debug builds.

However since the session-utils (commandline tools) depend on it, it had to be included with optimized bundles. Non-debug builds hide it by default since (except if you run Ardour directly from the source-dir without installation of set the config variable)

Thanks for your reply.
I have a use case where I need to use ardour only for MIDI an OSC. I would like to disable latency compensation as well.
I don’t even know if a soundcard will be present or not.
I could use jack with dummy driver, but it adds overhead.
So dummy driver is ideal for my use case, I think.
You say there is a config variable to enable dummy backend on optimized builds?

Yes there is a config variable to list the dummy/none backend with an optimized build as I described above.

Ardour’s Dummy engine does not have any hardware I/O: It cannot connect to physical MIDI interfaces. (jack -d dummy + a2jmidid can). Also note that the Dummy backend is not using realtime scheduling.

Sounds like a fancy project though. May I ask what-for you use Ardour to tie MIDI and OSC without actual soundcard?
Have you meanwhile found the config entry?

Sorry I had overlooked timbyr’s post.
I managed to get the dummy backend back by putting this in ~/.config/ardour5/config :

I will try to explain what I want to do.
The flexibility, of Ardour, and the fact that it has OSC and lua interfaces, made Ardour a very good candidate for what I try to achieve.

I have a device, let’s call it the master, that plays a track, and is able to periodically send information, using midi, about its current playhead position.
With an external program, I would like to receive this information, and make Ardour’s playhead follow the playhead of the master device.
So Ardour will play and send midi notes to other devices, in sync with the master.

You may think that I could simply use a midi clock…
but the thing is that the master device allows me to loop on some parts in real time, or to go back to a previous point in the song.

So I won’t need any soundcard, because no audio will be generated. Only MIDI.
And I try to achieve this on a raspberry pi, as you could see in my other posts.

Do you think I’m crazy now? :wink:

Sorry I forgot to say that the external program will receive MIDI from the master device, and ask Ardour, using OSC, to jump to the same position

Do you think I'm crazy now? ;-)

No, I think it’s a cool hack :slight_smile:

I still don’t see how Ardour communicates back to the outside world. Do you use a Lua script to send OSC? or do you poll via OSC?
It might indeed be overkill to use Ardour if all that you need is a time-master. Then again, it depends what else you may need in the future and what Ardour can offer to that end.

I have an external program that sends OSC to Ardour
Ardour moves the playhead and plays
And in the session you have midi tracks, which send events to the outside world

Except Ardour’s Dummy backend cannot send MIDI to the outside world. MIDI I/O is likewise a “dummy”, fake I/O, not actual hardware.