# Routing the output of ctcsound to /dev/null **URL:** \ **Category:** General\ **Created:** [February 11, 2021, 9:03am UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152 "2021-02-11T09:03:57Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![ulrikah](https://forum.csound.com/user_avatar/forum.csound.com/ulrikah/32/65_2.png) [@ulrikah](https://forum.csound.com/u/ulrikah)\ **Post date:** [February 11, 2021, 9:03am UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/1 "2021-02-11T09:03:57Z")
Hi, I’m using the ctcsound API to control the rendering process with performKsmps(). I’m analysing every _k_ and using the analysis to train a Pytorch model. I would like to send the output of the ctcsound rendering to /dev/null. I basically want to achieve what _–logfile=null_ does, but as it says in the [docs](http://www.csounds.com/manual/html/CommandFlags.html), this option only works when calling Csound from the command line. Is there a way to achieve this through the ctcsound API? I’ve tried to set sys.stdout and sys.stderr to /dev/null within a context, as suggested [here](https://stackoverflow.com/questions/6735917/redirecting-stdout-to-nothing-in-python). That works for pure Python code, but not for the parts that make calls to Csound. Routing all the Python logs to /dev/null is not an option since I want to be able to log other parts of my program. Any ideas? ---
**Author:** ![rory](https://forum.csound.com/user_avatar/forum.csound.com/rory/32/7_2.png) [@rory](https://forum.csound.com/u/rory)\ **Post date:** [February 11, 2021, 9:54am UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/2 "2021-02-11T09:54:40Z")
Hi @ulrikah I’m not overly familiar with the Phyton bindings, but can’t you use [csoundSetOption()](https://csound.com/docs/api/group___a_t_t_r_i_b_u_t_e_s.html#ga332ed5da3d399f0ae039906c380764e1) to specify what command line flags you wish to put in place? ---
**Author:** ![ulrikah](https://forum.csound.com/user_avatar/forum.csound.com/ulrikah/32/65_2.png) [@ulrikah](https://forum.csound.com/u/ulrikah)\ **Post date:** [February 11, 2021, 10:09am UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/3 "2021-02-11T10:09:24Z")
Unfortunately, that doesn’t seem to work. I’ve tried with some variations of the same option, and all seem to give me a CSOUND\_SUCCESS. However, even illegal options seem to give the same success code. The result is that Csound renders, but with all the standard logging. Here is the code for ref: ``` import sys import ctcsound csd_text = ''' -odac instr 1 out(linen(oscili(p4,p5),0.1,p3,0.1)) endin i1 0 5 1000 440 ''' cs = ctcsound.Csound() options = [ "--logfile=null", "-O null", "-Onull", "illegal_option" ] for option in options: if cs.setOption(option) != 0: raise Exception("Illegal option", option) result = cs.compileCsdText(csd_text) result = cs.start() while True: result = cs.performKsmps() if result != 0: break result = cs.cleanup() cs.reset() del cs sys.exit(result) ``` ---
**Author:** ![rory](https://forum.csound.com/user_avatar/forum.csound.com/rory/32/7_2.png) [@rory](https://forum.csound.com/u/rory)\ **Post date:** [February 11, 2021, 11:09am UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/4 "2021-02-11T11:09:11Z")
Can you create your own [message callback](https://csound.com/docs/api/group___m_e_s_s_a_g_e_s.html#ga45c8cd03e278274966232a12a0297313) and then simply ignore everything that gets piped to it from Csound? I prefer to use the [message buffer](https://csound.com/docs/api/group___m_e_s_s_a_g_e_s.html#ga01f4b4e4baabcd74c36500a4d27f776b), where you can pull and pop messages from it at your leisure. Again, I’ve no idea how these are implemented in ctcsound… ---
**Author:** ![ulrikah](https://forum.csound.com/user_avatar/forum.csound.com/ulrikah/32/65_2.png) [@ulrikah](https://forum.csound.com/u/ulrikah)\ **Post date:** [February 11, 2021, 11:45am UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/5 "2021-02-11T11:45:35Z")
That seems to have removed most of the output. Thanks! However, there is still some meta information that gets printed when I use messages: ``` 0dBFS level = 32768.0 --Csound version 6.15 (double samples) Nov 20 2020 [commit: 18c2c7897425f462b9a7743cee157cb410c88198] libsndfile-1.0.28 0dBFS level = 32768.0 --Csound version 6.15 (double samples) Nov 20 2020 [commit: 18c2c7897425f462b9a7743cee157cb410c88198] libsndfile-1.0.28 end of score. overall amps: 0.0 overall samples out of range: 0 0 errors in performance Elapsed time at end of performance: real: 0.000s, CPU: 0.000s ``` ---
**Author:** ![rory](https://forum.csound.com/user_avatar/forum.csound.com/rory/32/7_2.png) [@rory](https://forum.csound.com/u/rory)\ **Post date:** [February 11, 2021, 11:55am UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/6 "2021-02-11T11:55:39Z")
Hmm, I’m not sure how to get rid of that. I think we might need to ping @stevenyi! ---
**Author:** ![stevenyi](https://forum.csound.com/user_avatar/forum.csound.com/stevenyi/32/4_2.png) [@stevenyi](https://forum.csound.com/u/stevenyi)\ **Post date:** [February 14, 2021, 7:19pm UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/7 "2021-02-14T19:19:10Z")
I’m not too familiar with this part of the codebase, but I seem to remember similar issues discussed on the mailing list some time back. If there’s some example code that uses setMessageCallback() I can do a debug session to investigate. ---
**Author:** ![ulrikah](https://forum.csound.com/user_avatar/forum.csound.com/ulrikah/32/65_2.png) [@ulrikah](https://forum.csound.com/u/ulrikah)\ **Post date:** [February 15, 2021, 2:16pm UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/8 "2021-02-15T14:16:28Z")
Actually, it seems like setMessageCallback() [is deprecated in the latest version of ctcsound.py](https://github.com/csound/csound/blob/develop/interfaces/ctcsound.py#L1546). Right now, instead of creating a callback, I’m simply deleting the content of the buffer when I’m done rendering. ---
**Author:** ![joachim](https://forum.csound.com/letter_avatar_proxy/v4/letter/j/a87d85/32.png) [@joachim](https://forum.csound.com/u/joachim)\ **Post date:** [February 15, 2021, 2:51pm UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/9 "2021-02-15T14:51:34Z")
just to let you know that i asked françois pinot (the author of ctcsound) about this because he is not on this forum. his reply was: I’m afraid it’s not a ctcsound problem. You can try this in a python console: > > > import ctcsound > > > cs = ctcsound.Csound() > > > 0dBFS level = 32768.0 > > > –Csound version 6.15 (double samples) Oct 29 2020 > > > [commit: 89d14ffa12fcac632181b309dc5e4f3cf7b73085] > > > libsndfile-1.0.28 > > > del cs > > > end of score. overall amps: 0.0 > > > overall samples out of range: 0 > > > 0 errors in performance > > > Elapsed time at end of performance: real: 3.063s, CPU: 0.001s We see that python systematically echoes what’s coming back from ctcsound. For me, it’s a python problem… best - joachim ---
**Author:** ![stevenyi](https://forum.csound.com/user_avatar/forum.csound.com/stevenyi/32/4_2.png) [@stevenyi](https://forum.csound.com/u/stevenyi)\ **Post date:** [February 15, 2021, 4:30pm UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/10 "2021-02-15T16:30:00Z")
Yes there’s a bit of a chicken and egg issue here with Csound printing right at instantiation. I had to look again and in the C API there is this function: ```csound PUBLIC void csoundSetDefaultMessageCallback( void (*csoundMessageCallback)(CSOUND *csound, int attr, const char *format, va_list args)) { if (csoundMessageCallback) { msgcallback_ = csoundMessageCallback; } else { msgcallback_ = csoundDefaultMessageCallback; } } ``` That sets the default message callback. This is also used by the logging system. It is part of the C API but is not available in ctcsound.py. I wonder if this could be added to ctcsound to accomodate messages that happen during csound creation and deletion. ---
**Author:** ![fggp](https://forum.csound.com/user_avatar/forum.csound.com/fggp/32/67_2.png) [@fggp](https://forum.csound.com/u/fggp)\ **Post date:** [February 23, 2021, 11:06am UTC](https://forum.csound.com/t/routing-the-output-of-ctcsound-to-dev-null/152/11 "2021-02-23T11:06:23Z")
ctypes does not provide a clear way of dealing with varargs functions and I have actually no much time to study the problem. But I did add setDefaultMessageCallback to ctcsound.py; it’s not fully implemented but it will allow you to define a noMessage callback like this: ``` import ctcsound import sys def noMessage(csound, attr, flags, *args): pass csd_text = ''' -odac instr 1 out(linen(oscili(p4,p5),0.1,p3,0.1)) endin i1 0 5 1000 440 ''' ctcsound.setDefaultMessageCallback(noMessage) cs = ctcsound.Csound() result = cs.compileCsdText(csd_text) result = cs.start() while True: result = cs.performKsmps() if result != 0: break result = cs.cleanup() cs.reset() del cs sys.exit(result) ``` I hope this will help you and I’ll come back to this when I have more time… You can download the new ctcsound.py file directly from github ([https://github.com/csound/csound/blob/develop/interfaces/ctcsound.py](https://github.com/csound/csound/blob/develop/interfaces/ctcsound.py) Regards François