How accurate are MMC commands for triggering a sequencer live?

[BleedingEdgeProductions]

Hi folks,

 

How accurate (time wise) are MIDI Machine Control commands? If I were to send a locate command to a sequencer as a 'pre' cue, followed by a play command, followed later on by a stop command, would the sequencer respond instantly (ie good enough to use live)?

 

I am looking at the best way of playing back multitrack click tracks live (programs like CSC/SCS/SFX/QLab are fine up to a few channels, but I am looking at 20 channels + live inputs + processing with VST or RTAS plugins).

 

The sequencers I am looking at are Sonar (which I already have, so, ideal) or Pro Tools LE.

 

Many thanks,

 

Martin

[kitlane]

I would think MMC will do the job just fine. The locate commands work with SMPTE timecode so you can locate to at least a frame, possibly a fractional frame (i.e. 25th or 30th second for a frame and maybe one 100th of that for a fractional frame). On a sequencer the 'Play' command should be as "instant" as any other control mechanism. The 300ms it takes to press the button on hearing the 'Go' will be much more significant than any delay from the sequencer.

[BlueShift]

I'd say accuracy will be fine - also, its worth noting if there is a delay, it is most likely measurable and therefore tracks can be offset to compensate...

[BleedingEdgeProductions]

Thanks very much! I was slightly concerned at 'stuttering' at the start of playback as the MTC chases and locks...

 

M

[dbuckley]

Assuming you are not chasing timecode, it should operate at about the same speed as pressing the play button. With decent software on an adequate machine, that pretty much means it feels instant.

[kitlane]

Thanks very much! I was slightly concerned at 'stuttering' at the start of playback as the MTC chases and locks...

 

M

 

Do you need to chase timecode? What would the timecode source be? Apart from the sequencer what will be following the TC?

[BleedingEdgeProductions]

Thanks guys.

 

Regarding Timecode - I would have been using the Show Control software (probably SCS or CSC) as the MTC master. Various LX and other cues will be triggered at various points in the song, so it seemed reasonable to sync the two systems up. Is this not necessary? I'm not entirely sure of how prone to drift systems are in the context of short (3 minute or so) songs...

 

M

[jamesperrett]

I haven't done any MMC programming for a few years but I'm fairly sure that MTC is accurate to a quarter of a frame. There are two different alternative approaches - you can either have the sequencer chase MTC or you can use a song position pointer with the start, continue and stop commands. MMC is usually used for peripheral gear like tape machines rather than for controlling sequencers.

 

James.

[BleedingEdgeProductions]

Thanks James - it would seem that I don't need to sync to MTC at all, and just use the MMC commands (the sequencer is a glorified tape machine and mixer!).

 

Thanks,

 

Martin

[dbuckley]

You'll probably find that over three minutes drift wont be an issue when talking about modern electronic equipment.

 

When you sycn a 35mm projector to a tape player for several minutes, thats when you need timecode!