# Making Mplay.jl work under Linux
**URL:** https://discourse.julialang.org/t/making-mplay-jl-work-under-linux/56192
**Category:** General Usage
**Created:** [February 28, 2021, 2:19pm UTC](https://discourse.julialang.org/t/making-mplay-jl-work-under-linux/56192 "2021-02-28T14:19:21Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@tp2750](https://discourse.julialang.org/u/tp2750)
#### Post date: [February 28, 2021, 2:19pm UTC](https://discourse.julialang.org/t/making-mplay-jl-work-under-linux/56192/1 "2021-02-28T14:19:21Z")
Here’s how I got [Mplay.jl](https://github.com/JuliaMusic/Mplay.jl) to work under Linux (Ubuntu 20.04).
Mplay.jl writes to a “raw midi device”, and Ubuntu does not have those on by default.
To create a “virtual midi device” I do
```julia
$ sudo modprobe snd-virmidi snd_index=1
```
On my system they show up like this:
```julia
$ ls /dev/snd/midi*
/dev/snd/midiC3D0 /dev/snd/midiC3D1 /dev/snd/midiC3D2 /dev/snd/midiC3D3
```
The number “3” in “midiC3D0” is important, and depends on the number of physical soundcards on the system.
We also need a software synthesizer to turn the midi code into a sound signal. I use `fluidsynth` together with the `FluidR3 GM` soundfonts. On Ubuntu I get them like this (we will need alsa-utils also):
```julia
$ sudo apt install fluidsynth fluid-soundfont-gm alsa-utils
```
Then I can run `fluidsynth` in “server mode” (it blocks the terminal):
```julia
$ fluidsynth --server --audio-driver=alsa -o audio.alsa.device=hw:0 /usr/share/sounds/sf2/FluidR3_GM.sf2
>
```
Here the device “hw:0” is the soundcard on the motherboard, so the sound will come out of the headphones I plugged in the jack on the front of the computer.
Now we need to connect `fluidsynth` to the the virtual midi device. This is done using `aconnect` from alsa-utils.
First we need an overview of our system:
```julia
$ aconnect -l
client 0: 'System' [type=kernel]
0 'Timer '
1 'Announce '
client 14: 'Midi Through' [type=kernel]
0 'Midi Through Port-0'
client 28: 'Virtual Raw MIDI 3-0' [type=kernel,card=3]
0 'VirMIDI 3-0 '
client 29: 'Virtual Raw MIDI 3-1' [type=kernel,card=3]
0 'VirMIDI 3-1 '
client 30: 'Virtual Raw MIDI 3-2' [type=kernel,card=3]
0 'VirMIDI 3-2 '
client 31: 'Virtual Raw MIDI 3-3' [type=kernel,card=3]
0 'VirMIDI 3-3 '
client 128: 'FLUID Synth (5104)' [type=user,pid=5104]
0 'Synth input port (5104:0)'
```
My virtual midi devices are clients 28 to 31 and `fluidsynth` is client 128 (these numbers might be different on other systems).
Then I can connect the output of client 28 to the input of client 128 like this:
```julia
$ aconnect 28:0 128:0
```
The result should look like this:
```julia
$ aconnect -l
client 0: 'System' [type=kernel]
0 'Timer '
1 'Announce '
client 14: 'Midi Through' [type=kernel]
0 'Midi Through Port-0'
client 28: 'Virtual Raw MIDI 3-0' [type=kernel,card=3]
0 'VirMIDI 3-0 '
Connecting To: 128:0
client 29: 'Virtual Raw MIDI 3-1' [type=kernel,card=3]
0 'VirMIDI 3-1 '
client 30: 'Virtual Raw MIDI 3-2' [type=kernel,card=3]
0 'VirMIDI 3-2 '
client 31: 'Virtual Raw MIDI 3-3' [type=kernel,card=3]
0 'VirMIDI 3-3 '
client 128: 'FLUID Synth (5104)' [type=user,pid=5104]
0 'Synth input port (5104:0)'
Connected From: 28:0
```
Now we are ready to start Mplay.jl using the helper script in the `src` directory:
```julia
Mplay.jl/src$ bash Mplay.sh --device="hw:3,0" song.midi
```
Here the number “3” in “hw:3,0” is the same “3” as in `/dev/snd/midiC3D0`
With a bit of luck, your song will now play.
If not, try reconnecting the midi device and `fluidsynth` by doing
```julia
$ aconnect -x
$ aconnect 28:0 128:0
```
The graphical tool `aconnectgui` gives a graphical version of `aconnect -l`
I hope this can help others.
I’ve used these 2 midi tutorials:
- [The Linux MIDI-HOWTO : HOWTO Use MIDI Sequencers With Softsynths.](https://tldp.org/HOWTO/MIDI-HOWTO-10.html)
- [Ted's Linux MIDI Guide](http://tedfelix.com/linux/linux-midi.html)
There a lots of free midi file son the internet, eg here: [https://freemidi.org/](https://freemidi.org/)
---
### Author:  [@jheinen](https://discourse.julialang.org/u/jheinen)
#### Post date: [February 28, 2021, 5:06pm UTC](https://discourse.julialang.org/t/making-mplay-jl-work-under-linux/56192/2 "2021-02-28T17:06:17Z")
Thanks for the info. I tried the same with `timidity` and the system did no longer complain about open/write errors - but I couldn’t hear anything.
---
### Author:  [@tp2750](https://discourse.julialang.org/u/tp2750)
#### Post date: [February 28, 2021, 5:31pm UTC](https://discourse.julialang.org/t/making-mplay-jl-work-under-linux/56192/3 "2021-02-28T17:31:04Z")
I tried also with `timidity` is server mode (`timidity -iA`).
At first I got got no sound, but after playing a midifile directly `timidity song.midi` then it worked when retrying the server.
---
### Author:  [@jheinen](https://discourse.julialang.org/u/jheinen)
#### Post date: [March 1, 2021, 6:53pm UTC](https://discourse.julialang.org/t/making-mplay-jl-work-under-linux/56192/4 "2021-03-01T18:53:59Z")
The current master branch seems to work fine on Linux. The problem on my Linux box was that simple: the Timidity++ output was muted. I also fixed the console interface - the terminal settings were not reset correctly when leaving Mplay.
May be someone could test the GUI - IMO it should work. But my Ubuntu VM seems to have problems with the OpenGL software rasterization (although similar demos work).
---
### Author:  [@tp2750](https://discourse.julialang.org/u/tp2750)
#### Post date: [March 2, 2021, 5:05pm UTC](https://discourse.julialang.org/t/making-mplay-jl-work-under-linux/56192/5 "2021-03-02T17:05:02Z")
Thanks @jheinen for updating and also for updating the README.
I tested the --gui option.
On current master I get this error:
```julia
ERROR: LoadError: could not load library "/System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries/libGL.dylib"
/System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries/libGL.dylib.so: cannot open shared object file: No such file or directory
```
This is easily solved by this patch:
```julia
diff --git a/src/OpenGL.jl b/src/OpenGL.jl
index 0d9e63d..964d458 100644
--- a/src/OpenGL.jl
+++ b/src/OpenGL.jl
@@ -1,6 +1,7 @@
module OpenGL
-const libGL = Sys.KERNEL == :NT ? "C:/Windows/System32/opengl32.dll" : "/System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries/libGL.dylib"
+const libGL = Sys.KERNEL == :NT ? "C:/Windows/System32/opengl32.dll" :
+ Sys.KERNEL == :Linux ? "/usr/lib/x86_64-linux-gnu/libGL.so" : "/System/Library/Frameworks/OpenGL.framework/Versions/Current/Libraries/libGL.dylib"
const GL_LINES = 0x0001
export GL_LINES
```
However, with this patch, I get this error
```julia
bash src/Mplay.sh --device="hw:3,0" --gui song.midi
ALSA lib rawmidi.c:281:(snd_rawmidi_open_noupdate) Unknown RawMidi
midi: cannot open MIDI output
```
Which is strange, as this command plays the song (with the text interface):
```julia
bash src/Mplay.sh --device="hw:3,0" song.midi
```
Not sure how that come.
---
### Author:  [@tp2750](https://discourse.julialang.org/u/tp2750)
#### Post date: [March 2, 2021, 5:13pm UTC](https://discourse.julialang.org/t/making-mplay-jl-work-under-linux/56192/6 "2021-03-02T17:13:41Z")
This patch fixed the midi device error:
```julia
diff --git a/src/Mplay.jl b/src/Mplay.jl
index cc2d042..c2e18bd 100644
--- a/src/Mplay.jl
+++ b/src/Mplay.jl
@@ -318,7 +318,7 @@ export mplay
function main()
if length(ARGS) > 0
path = ARGS[1]
- device = length(ARGS) > 1 ? ARGS[2] : ""
+ device = length(ARGS) > 1 ? ARGS[2] : haskey(ENV, "MIDI_DEVICE")
mplay(path, device)
end
end
```
But now it fails like this:
```julia
ERROR: LoadError: MethodError: no method matching unsafe_convert(::Type{Ptr{UInt8}}, ::Bool)
Closest candidates are:
unsafe_convert(::Type{Ptr{UInt8}}, ::Symbol) at pointer.jl:57
unsafe_convert(::Type{Ptr{UInt8}}, ::String) at pointer.jl:59
unsafe_convert(::Type{T}, ::T) where T<:Ptr at essentials.jl:391
```
I guess I need to look closer at the differences between tui.jl and Mplay.jl