FAQ

b-tektracker FAQ
<boo_boo@inbox.ru>

General:

Q: Why did you forked from the tektracker?
A: Tektracker is'nt developing now, but i badly need some features.

Q: Is b-tektracker song file format compatible with tektracker?
A: No: bttrk can load tektracker song, but saves to its own format.


Problems:

Q: Program refuses to run, with error message about "RealTimeClock: Cannot 
open /dev/rtc" or "RealTimeClock: cannot set ownership of /dev/rtc"
displayed.
A: bttrk uses /dev/rtc realtime clock device to get acceptable sync. make 
sure you have appropriate permissions and /dev/rtc is'nt used by another
application.
Simplest solution to get /dev/rtc access is to run bttrk as root, 
but the best way is to use 'realtime-lsm' 
(http://sourceforge.net/projects/realtime-lsm/) or 'rlimits' linux kernel 
module to setup realtime priveleges for a non-root user.

Q: Is it possible to use bttrk with <some> softsynth?
A: Yes. You need to setup message forwarding from raw MIDI device to 
softsynth MIDI input.
In case of ALSA sound system this is fairly easy: load snd_virmidi driver,
setup bttrk to use its device file (see 'mididev' option in .bttrkrc),
then use aconnect (or kaconnect, or such) to attach virmidi output port 
to softsynth input port.

Q: When I try to play the keyboard like a piano in song mode, a note
plays twice when I hold a key down.  What's wrong?
A: The short answer is that you need to change your keyboard repeat delay
to a smaller value.  We suggest 250ms because that's the smallest
value you can set it to at the Linux console.
At the Linux console:
  kbdrate -d 250   # you will most likely have to run this command as root
In X:
  xset r rate 250

Here's the long answer:
The library that bttrk uses to handle keyboard input can report
that a key was pressed, but cannot report when it was released.
So bttrk checks for a keypress every tenth of a second.  If it gets
a keypress and isn't already playing a note, it starts playing.
If it gets a keypress and was already playing that same note, it continues
playing that same note. 
If it gets a keypress and was already playing a different note,
it stops the old note and starts playing the new note.
If it doesn't get a keypress, it checks to see if 250ms have passed
since the last keypress.  If 250ms have passed, it stops the note.
If less than 250ms have passed, it lets the note continue to play.
This can happen when you're holding a key down, but not enough time
has passed for the repeat delay to expire.

The drawback to this approach is that if you try to tap the same note very
quickly repeatedly, bttrk will treat it as if you held the key down.
It would be nice if we could set the repeat delay to one tenth of a second,
and while we can do that in X, we can't do it for the Linux console.