Add userbit support for LTC/SMPTE

[robertmcrostie]

Amazing bit of open source software.

Would it be possible to add UserBits to the LTC/STMPE in/out? I know not many people use or know if userbits but occasionally I have use them for controlling equipemnent while still using the same timecode range. Thanks.

[fiverecords]

Thanks, glad you're finding it useful!

Yes, this is doable. The LTC frame already carries 32 bits of user bits (eight 4-bit groups), and STC's encoder and decoder already lay the frame out correctly, so adding read/write for those bits is a fairly contained change.

To make sure I build it the way you need it: on the output side, are you looking to set a fixed value (e.g. an 8-digit hex field you enter once), or do you need the user bits to change over time? And on the input side, do you just want to see the incoming user bits displayed/logged, or feed them somewhere? Also, is there a particular format your equipment expects in those bits (raw hex, date, reel number...), or is it a value you define yourself on both ends?

Once I know that, I can put together a build for you to try.

[robertmcrostie]

Thanks, it is nice to have userbits working.

This is how I have or seen it used in the past:

1. We would set the userbits to be the date of when the laser show was created. The timecode track would be stripped with the same date in userbots so when the audio and timecode would play on a sony mini disk that had 4 tracks, the show would only run when the correct timecode and userbit were being sent. This was a bit of a safety so if there was a timecode test or similar with other timecode it would not trigger the show.  
2. I have used this to trigger different laser shows for an information centre using the same timecode but with different userbits that would play different laser shows that were loaded into the laser controller. It allowed us to use the same timecode with just change the userbits to trigger the different shows. This avoids lots of things like timecode free rolling and triggering another show etc etc. 

Functions that would be good to have:

1. Display of the userbits from the incoming timecode converted to a decimal number. Normally we would use say YYYYMMDD (I think that is correct from memory as it was a while ago).
2. Pass through option so what is received is transmitted out. This would only be relevant to LTC/SMTPE as not sure how the other types of timecode handle userbits. 
3. In generation mode allow the user to set the userbits.
4. Yes the userbits would be just a value that the user defines.
5. When you are using the system clock to generate timecode have the option of sending userbits as the current system date or setting it to another number. 
6. The other methods of timecode input and output I would think it is nice to have userbits set either from the original or changed to a value we have in the software.

I have not used userbits for a while but it does make the LTC/STMPE complete. Hopefully that all makes sense but if you have another way to do this I am happy either way.