Pd and Max externals for rtlsdr
Mac OS and Linux
Pd and Max externals for rtlsdr
Mac OS and Linux
Today was able to get the rtlsdr~ object running in Pd on Ubuntu 14.04 on a Macbook pro.
Audio quality seems rough. The only driver I could get to work was Alsa at 44.1KHz – may be able to get help with this from Pd community.
Ended up using 64bit libraries for librtlsdr and libusb-1.0 . In fact, needed to using the shared (.so) libraries, not the static ones (.a) due to a weird linker error. Its possible that it happened due to mixing shared and static and I might try again using both static for these 2 libs.
See notes from previous post about issues with USB capture, and non-root user in Linux – there are 2 flags on the cmake for rtlsdr that might help resolve both of these, but I wasn’t having any luck and needed to use the method described in previous post.
The source code for linux version is in the /usr/lib/pd-extended/extra/rtlsdr~ folder – and the test pd file is in ~/pd/rtlSDR-block.pd, along with some abstractions.
There is also a makefile to build a local version of rtl_fm (rtl_fm3.c) in ~/rtl-sdr-new/rtl-sdr/rtl-fm3/
This makefile mixes the static and shared libs with no problem… hmm…?
Need to package this stuff up and send it to pdsdr github with source for Max/Pd on mac and Pd on linux. + instructions… etc.,
Would like to try running on r-pi – but will need to adapt the test patch to receive Osc messages because there is no gui on r-pi
Also I am some skeptical about running at low sample rates for audio – we’ll see…
Just thinking, that even if I am not able to run rtlsdr~ on r-pi that we could adapt rtl_fm so it receives control input from Pd using Osc and work that way…
Proof of concept
The next step will be to clean up the external so it allows mode, frequency, gain setting – and doesn’t break.
Use Twitter and Puredata to make music from text characters
By AJ Faraday
Notes on compiling rtl_sdr in Mac OS – writing Max and Pd Externals.
Today I got the Pd external running – using essentially same source code as Max. There is occasional weirdness going on with audio clicks when starting/stopping the radio, but other than that it seems fine and it runs. wooHOO. More to follow…
Now have set up a skeleton for Pd, called rtlfmz~ (inside the Pd application bundle) which does absolutely nothing but compiles all of the project files and calls a function in rtl_fm. Next step will be to port the actual Max external code and do the conversion.
updates 3/38/2014 before working on Pd version
There is now a fairly solid max external (rtlfmz~) using a recent version for rtl_fm. Also there is a simple Makefile that compiles local version of rtl_fm3.c in:
There are very minor changes to rtl_fm.c (for includes) and also a local version of librtlsdr.a (librtlsdr32.a) that is 32 bit.
The current state of the Max external does both pre-demodulated and raw IQ output, but you can only run one copy of the object due to excess use of global variables and my uncertainty over how to run multiple devices, threading, etc., – but we’ll go with it an try porting to Pd now.
update 2/27 – converted to using new version of rtl_fm
I had been using an older version of rtl_fm –
renamed external to rtlfmz~ and now using new version as (rtl_fm3.c) in the project
In addition to recopying the librtlsdr.a – I also recopied all of the include files and added two new files
There is a different method of threading and reading which I haven’t looked at yet, but it is now doing what it did before inside Max, which is read FM for a few seconds and write audio data to a file
plan: Set up a circular buffer accessible to the output thread and to the max perform function. – then see if we can get it to run for a few seconds.
The main thing to think about is how to let the processing happen in another thread while returning control to max. Then there really should be a way to interrupt processing from max.
There needs to be a max instance variable that tells whether the radio is running or not. Then, when its time to stop – you just do all the cleanup stuff that is at the end of the rtl_fm main() function.
update 2/18/2014 – Max external
Now have rtl_fm function within the plussztz~ external
It detects, opens device, demodulates about 30 seconds of FM, and writes audio at 44.1kHz. to a file /tmp/radio.bin – which can be played by the play command
Changes to code included:
update 2/15/2014 – Max external
Have now successfully compiled a test external in Max 6.1.4 – name is plussztz~ and it includes the rtl_fm code. Made 2 changes so far:
Today I was able to write a simple makefile to compile the rtl_fm app using the libusb and librtlsdr dynamic libraries.
Pd requires i386 architecture for externals (i386) so I then compiled the app using static libraries and the i386 architecture.
libusb-1.0 already had a 32 bit version in /usr/local/lib/libusb32-1.0.a (note that this version also requires compiling these frameworks:
-framework foundation -framework iokit
For librtlsdr, I rebuilt, using cmake with the following flags:
cmake ../ -DCMAKE_OSX_ARCHITECTURES=i386 -DINSTALL_UDEV_RULES=ON
But did not install the result. See this link for details on building with cmake: http://sdr.osmocom.org/trac/wiki/rtl-sdr
This produced a 32 bit static version of librtlsdr.a that could be used for building the app.
See this Stack Overflow post for more on cmake and architectures: http://stackoverflow.com/questions/5334095/cmake-multiarchitecture-compilation
currently local version of this test is in: tkzic/rtl-sdr-tz/rtl_fm2/
The default makefile builds the 32 bit architecture.
Dr.B and BT in the studio with Muse.
This is based on the Max tutorials. I have only written one external (for Soft66LC2). But everything seems to be working well with minimal filtering. After watching the video, I think the next feature should be an AGC (automatic gain control) on the input stage.
For non-signal objects.
Very helpful reference.
By Johannes M. Zmolnig
Like the Max preset object.
I’ve used this page about a million times this week