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MTC midi time code Peter Elsea

March 26, 2011 | 11:36 am

Hi there,
please help !
I’m trying to build a MTC generator in Max. I’m using Peter Elsea’s documentation, that is a great work. One of his sub-patch, named ‘makeFF’, is set for 30 fps. Due to my ignorance, I can’t understand how to modify it to get 25 fps. Here is the patch, and some comments from Peter :

– Pasted Max Patch, click to expand. –

Many thanks for any help.
Cheers,


March 26, 2011 | 1:57 pm

By chance I did the same modification a while ago.
For 25 fps you need to replace the value 96 by 32 (ie. "1" of bit 5).

Btw, I think there is a typo in the bottom comment.
The code of 30 fps normal should be 3 (not 4).
Note that 2 bits (5,6) can represent only the value range 0-3.


March 26, 2011 | 2:28 pm

Many thanks broc, I’ll try this.
I’m thinking the same as you about the code of 30 fps.

Could you please help me to understand another part of this patch named ‘MakeMTC’ : I can’t understand why the unlist object increment the accum object by 2.
Here’s the part of the patch I’m talking about :

– Pasted Max Patch, click to expand. –

Many thanks,
Eric L.


March 26, 2011 | 3:05 pm

All technical details of MTC are explained in this original documentation.

http://www.ibiblio.org/emusic-l/info-docs-FAQs/MIDI-doc/MIDI-MTC.txt

Quote:
"Since it takes eight quarter frames for a complete time code message,
the complete SMPTE time is updated every two frames."


March 26, 2011 | 6:36 pm

Quite complex for me…
OK, many thanks, I’ll try to manage with this.
Eric L.


June 3, 2011 | 4:08 pm

Hi there,
I believe the number to edit is not 96 (which should identify the Least Significant nibble of Hours value) but 118 (the Most Significant nibble, wherein Time Code format is encoded) .
haven’t tried it yet but it should work like this:
118 for 30 fps
116 for 30 fps drop frame
114 for 25 fps
112 for 24 fps
…and many thanks to both Peter Elsea for the PRECIOUS tutorials and broc for the very useful link! :)

cheers
tom


June 3, 2011 | 6:28 pm

Hi tom,

notice the original question about "96" was referring to the FULL FRAME message.
Your edits are correct and also needed, but apply to QUARTER FRAME messages.


June 7, 2011 | 9:14 pm

hi,

can someone post a link to the Peter Elsea documentation???

i am Max noob! thankyou!


June 7, 2011 | 11:03 pm

ftp://arts.ucsc.edu/pub/ems/maxtutors/


June 8, 2011 | 2:06 pm

thanks broc!

will read. do you know is midiclock smoothing/averaging covered?


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