The Zynthian project

November 11, 2015 jeremymodule, raspberry, raspberry pi, raspberrypi, raspberrypi2, synth, synth module, zynaddsubfx, zynthian7 Comments

Recently I found out that I was not the only one trying to build a synth module out of a Raspberry Pi with ZynAddSubFX. The Zynthian project is trying to achieve the exact same goal and so far it looks very promising. I contacted the project owner to ask if he would be interested in collaborating. I got a reply promptly and we both agreed it would be a good idea to join forces. The Zynthian project has all the things that I still had to set up already in place but I think I can still help out. The Zynthian set-up might benefit from some optimizations like a real-time kernel and things like boot time can be improved. Also I could help out testing, maybe do some packaging. And if there’s a need for things like a repository, web server or other hosting related stuff I could provide those.

Protoype of the Zynthian project — Zynthian prototype

I’m very happy with these developments of our projects converging. Check out the Zynthian blog for more information on the current state of the project.

Switched to HTTPS

October 26, 2015October 26, 2015 jeremyhttps, sslLeave a comment

The title says it all. I bought a SSL certificate at Xolphin, installed it and then I had to hunt down all the things that didn’t work anymore. I even managed to render the HTTP version of autostatic.com unreachable for about a day. But now everything seems to be working so I activated a rewrite rule that redirects all HTTP traffic to HTTPS. There are some bits that might not work as expected (embedded videos not displaying, warnings about unsecure content) but most of my blog should be accessible now in a secure way. If you encounter any issues, please let me know.

The certificate I’m using is a Comodo Positive SSL certificate with Domain Validation. So I’m getting a padlock but not the green address bar, for a green bar you need at least an Extended Validation certificate and that gets a bit expensive. I generated an Apache SSL configuration with the Mozilla SSL Configuration Generator but left out the OCSP stuff. I did add the HSTS header (HTTP Strict Transport Security header) because it really helped with getting that desired A+ rating in the Qualys SSL Labs SSL Server Test.

Working on a stable setup

September 28, 2015October 24, 2015 jeremyalsa, audio, dac, folderol, godfrey, kernel, linux, midi, module, raspberry, raspberrypi, raspberrypi2, real-time, realtime, synth, synth module, systemd, usb, zynaddsubfxLeave a comment

Next step for the synth module project was to get the Raspberry Pi 2 to run in a stable manner. It seems like I’m getting close or that I’m already there. First I built a new RT kernel based on the 4.1.7 release of the RPi kernel. Therefore I had to checkout an older git commit because the RPi kernel is already at 4.1.8. The 4.1.7-rt8 patchset applied cleanly and the kernel booted right away:

pi@rpi-jessie:~$ uname -a
 Linux rpi-jessie 4.1.7-rt8-v7 #1 SMP PREEMPT RT Sun Sep 27 19:41:20 CEST 2015 armv7l GNU/Linux

After cleaning up my cmdline.txt it seems to run fine without any hiccups so far. My cmdline.txt now looks like this:

dwc_otg.lpm_enable=0 dwc_otg.speed=1 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 rootflags=data=writeback elevator=deadline rootwait

Setting USB speed to Full Speed (so USB1.1) by using dwc_otg.speed=1 is necessary otherwise the audio coming out of my USB DAC sounds distorted.

I’m starting ZynAddSubFX as follows:

zynaddsubfx -r 48000 -b 64 -I alsa -O alsa -P 7777 -L /usr/share/zynaddsubfx/banks/SynthPiano/0040-BinaryPiano2.xiz

With a buffer of 64 frames latency is very low and so far I haven’t run into instruments that cause a lot of xruns with this buffer size. Not even the multi-layered ones from Will Godfrey.

So I guess it’s time for the next step, creating a systemd startup unit so that ZynAddSubFX starts at boot. And it would be nice if USB MIDI devices would get connected automatically. And if you could see somehow which instrument is loaded, an LCD display would be great for this. Also I’d like to have the state of the synth saved, maybe by saving an .xmz file whenever there’s a state change or on regular intervals. And the synth module will need a housing or casing. Well, let’s get the software stuff down first.

Building a synth module using a Raspberry Pi

September 13, 2015October 24, 2015 jeremyfundamental, kernel, midi, module, osc, patchset, pcm2704, raspberry, raspberry pi, raspberrypi, raspberrypi2, real_time, realtime, synth, synth module, usb, zynaddsubfx, zynaddsubfx-ext-gui5 Comments

Ever since I did an acid set with my brother in law at the now closed bar De Vinger I’ve been playing with the idea of creating some kind of synth module out of a Raspberry Pi. The Raspberry Pi 2 should be powerful enough to run a complex synth like ZynAddSubFX. When version 2.5.1 of that synth got released the idea resurfaced again since that version allows to remote control a running headless instance of ZynAddSubFX via OSC that is running on for instance a Raspberry Pi. I looked at this functionality before a few months ago but the developer was just starting to implement this feature so it wasn’t very usable yet.

But with the release of ZynAddSubFX 2.5.1 the stabilitity of the zynaddsubfx-ext-gui utility has improved to such an extent that it’s a very usable tool. In the above screenshot you can see zynaddsubfx-ext-gui running on my notebook with Ubuntu 14.04 controlling a remote instance of ZynAddSubFX running on a Raspberry Pi.

So basically all the necessary building blocks for a synth module are there. Coupled with my battered Akai MPK Mini and a cheap PCM2704 USB DAC I started setting up a test setup.

For the OS on the Raspberry Pi 2 I chose Debian Jessie as I feel Raspbian isn’t getting you the most out of your Pi. It’s running a 4.1.6 kernel with the 4.1.5-rt5 RT patch set, which applied cleanly and seems to run so far:

pi@rpi-jessie:~$ uname -a
Linux rpi-jessie 4.1.6-rt0-v7 #1 SMP PREEMPT RT Sun Sep 13 21:01:19 CEST 2015 armv7l GNU/Linux

This isn’t a very clean solution of course so let’s hope a real 4.1.6 RT patch set will happen or maybe I could give the 4.1.6 PREEMPT kernel that rpi-update installed a try. I packaged a headless ZynAddSubFX for the RPi on my notebook using pbuilder with a Jessie armhf root and installed the package for Ubuntu 14.04 from the KXStudio repos. I slightly overclocked the RPi to 1000MHz and set the CPU scaling governor to performance. The filesystem is Ext4, mounted with noatime,nobarrier,data=writeback.

To get the USB audio interface and the USB MIDI keyboard into line I had to add the following line to my /etc/modprobe.d/alsa.conf file:

options snd-usb-audio index=0,1 vid=0x08bb,0x09e8 pid=0x2704,0x007c

This makes sure the DAC gets loaded as the first audio interface, so with index 0. Before adding this line the Akai would claim index 0 and since I’m using ZynAddSubFX with ALSA it couldn’t find an audio interface. But all is fine now:

pi@rpi-jessie:~$ cat /proc/asound/cards
 0 [DAC            ]: USB-Audio - USB Audio DAC
                      Burr-Brown from TI USB Audio DAC at usb-bcm2708_usb-1.3, full speed
 1 [mini           ]: USB-Audio - MPK mini
                      AKAI PROFESSIONAL,LP MPK mini at usb-bcm2708_usb-1.5, full speed

So no JACK as the audio back-end, the output is going directly to ALSA. I’ve decided to do it this way because I will only be running one single application that uses the audio interface so basically I don’t need JACK. And JACK tends to add a bit of overhead, you barely notice this on a PC system but on small systems like the Raspberry Pi JACK can consume a noticeable amount of resources. To make ZynAddSubFX use ALSA as the back-end I’m starting it with the -O alsa option:

zynaddsubfx -r 48000 -b 256 -I alsa -O alsa -P 7777

The -r option sets the sample rate, the -b option sets the buffer size, -I is for the MIDI input and the -P option sets the UDP port on which ZynAddSubFX starts listening for OSC messages. And now that’s the cool part. If you then start zynaddsubfx-ext-gui on another machine on the network and tell it to connect to this port it starts only the GUI and sends all changes to the GUI as OSC messages to the headless instance it is connected to:

zynaddsubfx-ext-gui osc.udp://10.42.0.83:7777

Next up is stabilizing this setup and testing with other kernels or kernel configs as the kernel I’ve cooked up now isn’t a viable long-term solution. And I’d like to add a physical MIDI in and maybe a display like described on the Samplerbox site. And the project needs a casing of course.

CarPC v1.0

July 13, 2015October 24, 2015 jeremy8192cu, access, audio, car, carpc, cubieboard, cubieboard2, debian, hostapd, jessie, linux, mpd, mpdroid, pc, pcm2704, point, realtek, remote, rtl8192cu, sunxi, wifi2 Comments

As our collection of MP3 CD’s was wearing out I thought why not put a small embedded board with a big drive in our car? I dug up a Cubieboard2 that was gathering dust and started hacking. The goal:

Small system based on Debian Jessie
MPD to serve the audio files
Remote control via WiFi
Big drive
Acceptable boot time
Basic protection against file system corruption

Putting a bog standard Debian Jessie on the Cubieboard2 was quite straightforward with the help of the linux-sunxi.org wiki. The board booted with the standard kernel but unfortunately no sound. Luckily I had just received some ultra-cheap PCM2704 USB audio interfaces and these worked and sounded great too. WiFi worked out of the box but the rtl8192cu driver of the 3.16 kernel for the Realtek RTL8192CU chipset has the tendency to quickly go into suspension and as this driver doesn’t have any power management options I ended up with a hacky for loop in /etc/rc.local that pings all IP’s in the DHCP range. I quickly dropped this iffy set-up as it just didn’t work out that well and ended up using a DKMS based solution that made it possible to control power management of the WiFi dongle. Next hurdle was hostapd that stopped working with this alternative driver. But with the help of the hostapd-rtl871xdrv GitHub repo I managed to cook up a fully working hostapd Debian package.

Next up was the hard drive. I first tried a USB drive but the Cubieboard2 just couldn’t provide enough juice to power the drive properly together with the WiFi dongle. I also tried with my Raspberry Pi’s but those had the same issues. So I had to resort to a SATA drive. Of course I bought a 3.5″ drive first because those are cheaper. But you can’t power a 3.5″ drive with the SATA cable that comes with the Cubieboard2 and as I had a bit of a deadline I returned it for a 2.5″ drive and that works like a charm. I installed MPD, copied my music collection to the hard drive, fired up MPD and was greeted with a segmentation fault. Apparently the Jessie MPD package has issues with the sticker database file so I installed MPD from the backports repo and that version runs without any complaints so far.

For some basic protection against corruption by sudden power loss I created separate partitions for /home and /var on the SD card that are mounted rw with a couple of options to reduce corruption (sync,commit=1,data=journal) and / is mounted ro, just like the big hard drive with the audio files. /tmp is being mounted as tmpfs in RAM. Boot time is about 15 seconds and I’m OK with that. To remotely shut down the CarPC via WiFi I use a JuiceSSH homescreen shortcut of a connection that runs a simple shutdown -h now snippet.

After I had mounted everything in our car the thing wouldn’t boot though. Swapped the 1A USB car adapter for a 2.1A version and then the CarPC came up properly. Installed MPDroid on my Nexus 5 to control MPD via WiFi and so far, so good!

Cubieboard2 based CarPC

Addendum

Sometimes the CarPC became unreachable via WiFi. The culprit was that the DHCP service (udhcpd) didn’t always come up because it was sometimes started before hostapd. I fixed this by copying /var/run/systemd/generator.late/udhcpd.service to /etc/systemd/system/udhcpd-custom.service and adding hostapd.service to the After line and adding a Requires=hostapd.service line. I also added a [Install] stanza with the line WantedBy=multi-user.target. I then disabled udhcpd.service and enabled udhcpd-custom.service.

Addendum 2

Hostapd didn’t always start flawlessly either so I copied /var/run/systemd/generator.late/hostapd.service to /etc/systemd/system/hostapd-custom.service and added sys-subsystem-net-devices-wlan0.device to the After and Wants lines. Also added an [Install] stanza, disabled hostapd.service and enabled hostapd-custom.service.

Packaging Python Stuff

January 13, 2015 jeremyfalktx, launchpad, package, packaging, pbuilder, python, tunaLeave a comment

While packaging Tuna I ran into an issue for which I couldn’t easily find a workaround on the ubiquitous search engine. Tuna depends on some unavailable Python applications so those had to be packaged too. After having successfully tested the packages locally with pbuilder I uploaded them to Launchpad and noticed that they failed to build. Apparently the Python installer setup.py wants to install in /usr/lib/python2.7/site-packages and while that worked fine locally with pbuilder, Launchpad had an issue with that:

Found files in /usr/lib/python2.7/site-packages (must be in dist-packages for python2.7). debian/python-schedutils/usr/lib/python2.7/site-packages debian/python-schedutils/usr/lib/python2.7/site-packages/schedutils.so debian/python-schedutils/usr/lib/python2.7/site-packages/schedutils-0.4-py2.7.egg-info dh_builddeb.pkgbinarymangler: dpkg-deb --build debian/python-schedutils .. returned exit code 1 make: *** [binary-arch] Error 1 dpkg-buildpackage: error: /usr/bin/fakeroot debian/rules binary-arch gave error exit status 2

Apparently the files had to be installed in /usr/lib/python2.7/dist-packages but how to instruct the installer to do so without having to resort to ugly hacks? As I couldn’t find any useful answers on the web I asked falkTX on #kxstudio. He said the setup.py installer has a flag to install to dist-packages instead of site-packages, --install-layout deb. So I added that to the debian/rules file and gave it another spin:

#!/usr/bin/make -f # -*- makefile -*- # Sample debian/rules that uses debhelper. # This file was originally written by Joey Hess and Craig Small. # As a special exception, when this file is copied by dh-make into a # dh-make output file, you may use that output file without restriction. # This special exception was added by Craig Small in version 0.37 of dh-make.

# Uncomment this to turn on verbose mode. #export DH_VERBOSE=1 %: dh $@ override_dh_auto_build: python setup.py build

override_dh_auto_install: python setup.py install --skip-build --prefix /usr --root $(CURDIR) --install-layout deb

Now both pbuilder and Launchpad built the package without any issues.

LV2 gaining momentum

February 2, 2014 jeremyardour, audio, beatslash_lv2, bitrot, blop, carla, dave, deteriorate_lv2, drobilla, dssi, falktx, gareus, host, ladspa, linux, lv2, midifilter_lv2, objectivewave, plugin, qmidiarp, rgareus, robillard, robin, x422 Comments

The number of new LV2 plugins being released is steadily growing. The last couple of months at least the following LV2 plugins have been released:

Bitrot (a set of LV2 and LADSPA plugins for glitch effects)
beatslash-lv2 (a set of plugins for live beat repeating and beat slicing)
deteriorate-lv2 (a set of plugins to deteriorate the sound quality of live inputs)
midimsg-lv2 (a set of plugins to transform midi output into usable values to control other plugins)
QmidiArp (LV2 plugins of the three QMidiArp modules)
x42-plugins (collection of LV2 plugins: tuner, oscillator, x-fader, audio-level meters, midi filters etc.)
BLOP-LV2 (port of the LADSPA BLOP plugins)

Haven’t tried them all of them yet but the ones I did try (the QmidiArp modules as plugins and some of the x42 plugins) proved to be very promising. Besides new plugins being released work continues on a great number of plugins, the LV2 framework itself and on tools facilitating in the creation or building of LV2 plugins. Especially falkTX is in the vanguard with his current work on getting his Carla plugin host to work as a LV2 plugin. This would open up a lot of possibilities like using it in hosts that don’t support all plugin frameworks (think Ardour and DSSI support). In the meanwhile the guitarix team continues to add great LV2 plugins to their ever growing collection and Dave Robillard, the main author of LV2, doesn’t sit still either with releasing updated versions of the building blocks that form the LV2 framework.

Bitwig Studio to be released

February 2, 2014 jeremyableton, audio, bitwig, cross_platform, daw, dssi, java, juce, ladspa, linux, lv2, plugin, studio, toolkit, tracktion, vstLeave a comment

The 26th of March Bitwig Studio will be released. From the Bitwig Studio site:

Bitwig Studio is a multi-platform music-creation system for production, remixing and performance with a focus on flexible editing tools and a super-fast workflow.

It’s being developed by folks who have worked on Ableton Live and it will also be available for Linux. It’s a cross-platform DAW which means that for the GUI a platform agnostic framework has been used. In the case of Bitwig Studio the chosen framework is most probably Java which raised some eyebrows within the Linux Audio community. The price of the upcoming product met some scepticism too as it ends up higher than initially announced. Add to this that there’s barely any support for plugins (except native Linux VST) and you’ll understand that this upcoming release has fueled a discussion or two.

I haven’t seen anything yet of Bitwig Studio so I can’t judge the quality, workflow or usability of the product. I’ve registered for a beta testing account two years ago and didn’t hear anything from the Bitwig folks until recently so to be honest I completely lost interest in the product in the meanwhile.

Really, the people from Tracktion do it a lot better in that regard I think, it’s cheaper, they communicate more and it’s based on a cross-platform toolkit that has more credibility (Juce). But you never know, maybe I’ll get blown away when I get my hands on Bitwig Studio. You’ll be the first to hear.

A week without a Mac

January 12, 2014 jeremy12.04, 13, 2i4, 3, 9333, dell, developer, edition, focusrite, k290, logitech, lts, lubuntu, pangolin, precise, scarlett, sputnik, ubuntu, usb, xps4 Comments

Got my new workstation last week. Ultimately I decided to opt for a Dell notebook system with Linux pre-installed. So that left me only one single option: the XPS 13 Developer Edition, aka Sputnik 3. After having worked with it for a week I can only say I’m very, very happy with it. Unboxing it was a joy in itself, unwrapping the amazingly sleek machine and booting it for the first time. The XPS 13 comes with Ubuntu 12.04 LTS pre-installed which is just fine for me, especially given the fact that everything seems to work flawlessly so far. I haven’t rebooted it for days for example, suspending it works brilliantly and when I open the lid the device wakes up instantly, even after having it closed for days. And even though it has an i7 CPU it can run for hours on a full battery. The touch screen is a nice bonus but I haven’t really made use of it yet, it could be quite cool for live perfomances though. I’ve tested the touch screen with seq24 and it’s quite awesome to be able to trigger sequences by pressing the sequences on your screen.

Dell XPS 13 Developer Edition

I did try a fresh install but it would take me a bit too much time to get everything working properly so in the end I opted for sticking with the default install and install the Lubuntu desktop on top of it. And the default install doesn’t get in the way so I’m all set. I’m now looking for a nice keyboard and mouse to pair with the notebook, I’d greatly appreciate any suggestions. I had already ordered a Logitech K290 but I’m sending it back because it has the function keys swapped with the media keys and I just can’t work with that. Switching tty’s with Fn+Ctrl+F[:digit:] is just impossible to do with that keyboard. I could’ve tried swapping the keys but I’ve already filled in the RMA form and repacked the keyboard so it’s going back.

Next up is configuring it for making music. I’m thinking about purchasing a new USB audio interface, preferably USB2.0, that matches well with this machine. Suggestions are very welcome. I’ve looked at the Focusrite Scarlett 2i4 but a recent thread on LAU raised some doubts. We’ll see, it’s something for later, for now I’m extremely happy with my new work horse.

Resolved JACK issues on notebook

December 29, 2013 jeremyaudio, bluetooth, bto, bus, clevo, connection, driver, generic, hub, hyperthreading, interface, jack, jack1, jack2, jackd, jackd1, jackd2, kernel, kit, linux, matching, notebook, onboard, rate, sound, tree, unbind, unbinding, usb, webcam, wifi, xruns1 Comment

Finally got around troubleshooting the issues I was facing with JACK on my notebook, a BTO that is actually a Clevo W170ER. Somehow I couldn’t go lower than -p128 with USB audio interfaces. When I thought I had tried every option, even disabling hyperthreading, I noticed two unidentified entries in my lsusb output:

Bus 001 Device 003: ID 8087:07da Intel Corp. 
Bus 002 Device 003: ID 5986:0401 Acer, Inc

The first entry is a Bluetooth adapter and the second entry is a webcam. Both devices are unnecessary when making music so I thought, why not unbind them. First I had to figure out their respective bus ID’s:

$ tree /sys/bus/usb/drivers/usb
/sys/bus/usb/drivers/usb
??? 1-1 -> ../../../../devices/pci0000:00/0000:00:1a.0/usb1/1-1
??? 1-1.3 -> ../../../../devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.3
??? 2-1 -> ../../../../devices/pci0000:00/0000:00:1d.0/usb2/2-1
??? 2-1.6 -> ../../../../devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.6
??? bind
??? uevent
??? unbind
??? usb1 -> ../../../../devices/pci0000:00/0000:00:1a.0/usb1
??? usb2 -> ../../../../devices/pci0000:00/0000:00:1d.0/usb2
??? usb3 -> ../../../../devices/pci0000:00/0000:00:14.0/usb3
??? usb4 -> ../../../../devices/pci0000:00/0000:00:14.0/usb4

Since the Bluetooth adapter sits on bus 1 and the webcam on bus two their respective ID’s should be 1-1 and 2-1. So I echoed the ID’s to the unbind file in the same directory:

$ echo -n "1-1" | sudo tee /sys/bus/usb/drivers/usb/unbind
$ echo -n "2-1" | sudo tee /sys/bus/usb/drivers/usb/unbind

Good riddance:

$ lsusb
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub

Then I started JACK again with -p64 using an USB audio interface connected to bus 3 (so no rate matching hub in between) and no more xruns, not even with a generic kernel and using WiFi and all. Next hurdle is the onboard sound. Below -p128 I get bursts of massive xruns and so far I didn’t manage to pinpoint the culprit.

Edit #1: I’ve found out that the Bluetooth adapter is the main bottleneck. Also, by echoing the aformentioned ID’s (1-1 and 2-1) you disable the whole USB bus apparently. To disable just the USB device echo the last ID in the respective path names, so for the Bluetooth adapter that’s 1-1.3 and for the webcam 2-1.6. This way you can still use the USB bus on which these devices are residing. In my case disabling the whole bus is not an option, this would mean I’d have to connect all my USB interfaces to bus 3 (bus 4 doesn’t have any external inputs) which could result in these devices getting in each other’s way with regard to bandwidth. After echoing the ID’s the output of the tree command looks like this:

$ tree /sys/bus/usb/drivers/usb
/sys/bus/usb/drivers/usb
??? 1-1 -> ../../../../devices/pci0000:00/0000:00:1a.0/usb1/1-1
??? 2-1 -> ../../../../devices/pci0000:00/0000:00:1d.0/usb2/2-1
??? bind
??? uevent
??? unbind
??? usb1 -> ../../../../devices/pci0000:00/0000:00:1a.0/usb1
??? usb2 -> ../../../../devices/pci0000:00/0000:00:1d.0/usb2
??? usb3 -> ../../../../devices/pci0000:00/0000:00:14.0/usb3
??? usb4 -> ../../../../devices/pci0000:00/0000:00:14.0/usb4

The lsusb command still shows the devices though.

Edit #2: unbinding drivers like described above won’t persist across reboots. If you’d like to make the unbinding persistent you could add the unbind command to /etc/rc.local or create a script that runs at login. There are other options of course like blacklisting the Bluetooth drivers.