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about metro following transport did you know # 32

October 21, 2011 | 10:03 pm

Just tried the ‘Did you know’ #32 trick about metros synchronised to transport and the ‘metro 8n @active 1′ behaves as described but the ‘metro 8n @autostart 1 @autostarttime 0′ doesn’t : it just behaves like the other one, starting anywhere I start the transport from, without rewinding. Someone else tried it ?


October 22, 2011 | 12:33 am

I’ll bet the following might be the source of your misunderstanding.

If you start the transport from time 0, autostart turns the left metro on. If you then stop the transport, the metro is still "on", but it’s just not moving forward. When you start the transport again, metro continues to move forward, even though you haven’t rewound the transport to 0. If you turn the left metro off explicitly by sending it a 0 or stop message, then try, you’ll see what I think you expect to see.

Get the difference between the metro being on and the transport being moving?


October 22, 2011 | 8:46 am

Ok, now i got it. After experiencing more with this, (I’ve created 2 such metros patched to makenotes), I noticed that the only way to make both start together in a consistant way is to turn on both with a toggle. I guess it’s the same logic ?

– Pasted Max Patch, click to expand. –

October 22, 2011 | 3:56 pm

The transport is a clock that’s controlled by the transport object, and in the case of Max for Live is controlled by the Live transport. At any given moment it’s either on or off (i.e. running or not) and is at a particular point in time according to its own sense of where time 0 was. A metro can be on or off completely independently of whether the transport is on or off, but if the metro is tied to the transport (i.e., is using tempo-relative time units) it won’t move forward in time unless the transport is on.

The autostarttime attribute of metro simply sets a timepoint at which that metro will be turned on. The timepoint must be reached for that to happen, which implies that the transport must be on for it to happen. However, stopping the transport does not send a ‘stop’ message to the metro, it just halts the clock, which halts the metro even though the metro is still in its "on" state.

There are several ways to get metros to start at the desired time and to be synchronized tightly. In the instance your describe, it will be best if they are started at the same instant and/or are quantized to a particular time unit. You could do that with a mouse click on the same toggle object, as you suggest, or by giving them the same autostarttime, or with a bang from the same timepoint object.

I suggest to check out the ‘quantize’ attribute of metro (and other timing objects), and also to check out the timepoint object.


October 22, 2011 | 4:12 pm

Example:

– Pasted Max Patch, click to expand. –

October 22, 2011 | 7:06 pm

Thanks Christopher for this example patch. I had stumbled upon the timepoint objects in my investigations. Had a patching session this afternoon around a midi note shifter that made me understand crucial points about timing, midi, etc.
It often strikes me to see how much the max community is involved and helpful !


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