Python-rtmidi, pyext

Reply to Python-rtmidi, pyext on Mon, 24 Feb 2014 00:14:27 GMT

royal_orchestra — Mon, 24 Feb 2014 00:14:27 GMT

Hi,
I had some problems with midi on raspberry pi and made an external with pyext to get midi in and out on an alternative way for troubleshooting. I did this to learn some more python, also.
To my surprise some irregular audio i/o warnings and clicks i had before did not show up using this externals anymore.( closed any midi connections in the pd-midi dialogue.)
I got curious and measured hardware midi roundtrip latency using the timer-object. Compared with pd's alsa-midi and oss-midi it is much faster.
I read somewhere pd's midi is somehow synced to the audiobuffersize, perhaps this is the reason midi is faster via python(?)
The script relies on the python-rtmidi library
https://pypi.python.org/pypi/python-rtmidi
(rtmidi is a C++-library)
You need pyext installed in pd's startup-folder to use it within pd:
http://grrrr.org/research/software/py/
I attached the script (needs to be in the pd-path) and a pd patch to demonstrate and test it.
On my Raspberry Pi i measured usually 2.3ms lateny using rtmidi (min. 1.3, max 4ms) and ~5.3ms using pd's alsa-midi and the built-in objects (min 4, max 6.6), running headless with no gui, audiobuffersize 6.

Tested with Raspbian wheezy, pd-extended 0.43.4, python 2.7.3, pyext 0.2.2
I'm learning python, suggestions welcome
Jens

http://www.pdpatchrepo.info/hurleur/rtpyio.zip

Reply to Python-rtmidi, pyext on Mon, 24 Feb 2014 13:19:39 GMT

royal_orchestra — Mon, 24 Feb 2014 13:19:39 GMT

Here is the pyext build i made on my raspberry pi. If you don't want to compile pyext for raspberry by yourself, you could try it first.

http://www.pdpatchrepo.info/hurleur/py.pd_linux

Reply to Python-rtmidi, pyext on Tue, 17 Jun 2014 22:34:53 GMT

rduenas — Tue, 17 Jun 2014 22:34:53 GMT

Hi,

I tried your compiled object, pd finds the object and then throws:
"./py.pd_linux cannot open shared object file: No such file or directory"

Do you know what can be happening? Thanks

Ric

Reply to Python-rtmidi, pyext on Mon, 03 Nov 2014 13:58:23 GMT

royal_orchestra — Mon, 03 Nov 2014 13:58:23 GMT

Sorry, I don't know...
pd can't use the external above on other hardware than RPi.
If your on RPi, it should work, when you put it in the startup- folder. | import py | tends to crash pd.
General Documentation and example patches / scripts for pyext can be found here:
http://grrrr.org/research/software/py/
Perhaps a path is different on our RPis?
I think you should try to compile it on your RPi, then.