Scratching my head over the image compile script failing.
ref: https://github.com/alexmacrae/SamplerBox/blob/master/isoimage/samplerbox_iso_maker.sh

It seems calling both systemctl stop [email protected] and/or systemctl enable /etc/systemd/system/samplerbox.service at the end of the script is causing this fail message:

Failed to get D-Bus connection: Unknown error -1
ref: https://github.com/alexmacrae/SamplerBox/blob/master/isoimage/samplerbox_iso_maker.sh#L308

Prior to this I it was failing at the very end trying to umount devices:

umount: /home/pi/SamplerBox/img_maker/sdcard: target is busy
        (In some cases useful info about processes that
         use the device is found by lsof(8) or fuser(1).)
device-mapper: remove ioctl on loop0p3 failed: Device or resource busy
device-mapper: remove ioctl on loop0p2 failed: Device or resource busy
device-mapper: remove ioctl on loop0p1 failed: Device or resource busy

ref: https://github.com/alexmacrae/SamplerBox/blob/master/isoimage/samplerbox_iso_maker.sh#L321

There's also the reoccurring fail message Failed to read /proc/cmdline. Ignoring: No such file or directory - however I'm sure I've noticed this appear previously on what would become a successful compile.

Are all, or some of these things related?

Much needed for instruments like piano
josephernest#10

Just tested this solution for getting MIDI to work, fixed it for me in Pi2 and 3:
josephernest#24 (comment)
Serial midi on recent images · Issue 24 · josephernest/SamplerBox
Cuki posted Jan 18, 22:02: I confirm what was also observed by r.meurer (posted Nov 17, 16:53:) and jpg (posted Jan 8, 23:04:) on the samplerbox forum I could make serial MIDI work with samplerbox_...
github.com
and I also had to systemctl stop [email protected]

When restarting the main samplerbox.py script, garbage characters appear and will not clear even after GPIO.cleanup() is called during a KeyboardInterrupt exception, and RPLCD.CharLCD is initialized during the restart.

The bug does not occur every time. It seems to be more likely to occur when the system is busy, eg loading samples, however it can still occur any time SamplerBox is restarted.

It will not occur if:

• the Raspberry Pi is powered off and on
• 5V power to the LCD is disconnected and reconnected (ie physically resetting the module)

I suspect this may have something to do with the application being multithreaded but I haven't been able to determine this as a factor.

http://www.samplerbox.org/forum/304
I measured ~80ms as well

Objective

Since Raspberry Pi 3s have WiFi built in (and other versions can use a dongle), we can make use of this for a number of things, eg downloading sample-sets directly to the box!

Issues

Connecting to a wireless network is currently cumbersome. The user needs to first connect to a monitor or set up SSH via ethernet, and modify /etc/wpa_supplicant/wpa_supplicant.conf. The package wpa_config helps to simplify this process, but it still requires a monitor or SSH.

Using just 4 GPIO buttons to enter a password is the biggest challenge. Perhaps a new hardware requirement is to have more button(s) or perhaps a rotary encoder.

Tasks

1. Create a menu item that can get a list of available wireless hotspots (easy)
2. Allow the user to input a password
   1. Character dictionary
   2. Enter a password with only 4 buttons (left, right, enter, cancel) <- this is the biggest problem to solve
   3. Obscure password characters with * characters a short time after
   4. LCD cursor mode to blink ( lcd._set_cursor_mode(CursorMode.blink) ) to indicate position
   5. If a mistake is made, what happens? Must the user go back?
3. Remount read-write to save new network (wpa_config makes this easy)

A very odd issue with no sound on RPi 1 B+.

Samplerbox opens the port without issues and seems to play something (there is a data stream sent to DAC) but there is no waveform on the output, as if the sound stream has zero volume or something like it.

Aplay works, and so does 'official' SamplerBox code. Doesn't seem to be a kernel/driver/hardware issue.

Pi3 works flawlessly, and Pi2 likely will too so I'd consider this one a minor issue.

A start was made in audiocontrols.py. Test and implement.

Implemented here: josephernest@5a6d187 however there may be other factors to investigate.

MIDI has a built-in data compressing technique which doesn't seem to be supported at the moment.

Here's a patch for legacy MIDI protocol parser
paul-at@dd35f65