Linux-audio-dev

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4 participants
7538 discussions

Re: [linux-audio-dev] How to access "real-time" capabilities

by Jonathan Woithe

Lee Revell wrote: > On Fri, 2005-06-10 at 11:12 -0700, Ian wrote: > > Can anyone tell me *very briefly* what is the current > > state of play regarding realtime-lsm in the 2.6.* > > kernels and whether this feature (or something like it > > ) is likely to be introduced into the kernel anytime > > soon. > > realtime-lsm should be considered deprecated. The solution accepted by > Linus is rlimit based. I think this will be in 2.6.12 (seems to be in > the release candidates). Check the archives for "rlimit". > > This will require patching PAM and bash. In the interim you could try set_rtlimit: http://www.physics.adelaide.edu.au/~jwoithe/set_rtlimits-1.1.0.tgz It allows you to access the enhanced rlimits (ie: RT scheduling and nice levels) under 2.6.12 kernel or later without needing to patch anything. In fact, even once PAM/etc are patched this might be preferred by some since it allows you to control the limits based on the program being run; so for example you can allow /usr/local/bin/ardour to run at realtime priority 50 while /usr/bin/yes (for example) can't. Regards jonathan

20 years, 8 months

Re: [linux-audio-dev] Re: Looking for fast integer resampling code

by Kjetil Svalastog Matheussen

Erik de Castro Lopo: > > > > I recently did a lot of benchmarking between libsamplerate and mus_src > > in clm/sndlib. My result was quite interesting, the fastest mus_src sinc > > resampler where a lot faster than the fastest libsamplerate resampler. > > I think most people would agree that speed is not the most important > aspect when measuring the quality of a sample rate converter. > I was primarily testing speed, but both libraries where using the sinc routine, so... > With libsamplerate, I can state that the three sinc based converters > have the following characteristics: > > SNR Bandwidth > SRC_SINC_FASTEST 102.42 dB 80.23 % > SRC_SINC_MEDIUM_QUALITY 98.99 dB 90.68 % > SRC_SINC_BEST_QUALITY 97.43 dB 96.96% > > where SNR is signal to noise ratio and Bandwidth its a percentage of > the theoretical best bandwidth (ie half of the minimum of the source > and desination sample rate). > > > A third program is the original sinc-resampler from Julius Smith: > > http://ccrma-www.stanford.edu/~jos/resample/ > > I don't know how this one performs compaired to the other two though. > > libsamplerate the same algorithm as this one. I think Julius O. Smith > developed this algorithm. > He did, and Bil Schottstaedt used this algorithm as well for mus_src. When I compaired mus_src with width=5, and libsamplerate with SRC_SINC_FASTEST, the first one is much faster, I don't know what kind of SNR/Bandwidth you get with your way of measuring when using mus_src with width=5, but the source is easy to read so I guess you can figure it out. --

20 years, 8 months

[linux-audio-dev] Re: Looking for fast integer resampling code

by Kjetil Svalastog Matheussen

Dave Chapman: > > The most common case will be downsampling 48KHz->44.1KHz, but there are > also users who need upsampling from various lower frequencies (e.g. for > use with audio books). > > So we're looking for pointers to any high quality (but fast!) resampling > code that could be used. I recently did a lot of benchmarking between libsamplerate and mus_src in clm/sndlib. My result was quite interesting, the fastest mus_src sinc resampler where a lot faster than the fastest libsamplerate resampler. I don't have the results available right now, but I remember that mus_src performance wasn't very far from beating the linear resampler in libsamplerate. I did a lot of test with various types of data and compiler-options, so I don't think it was a coinsidence. However, it might have been because of some optimalization gcc was doing or something to do with the cache. The mus_src code is far smaller and easier to read than the one for libsamplerate. I did not hear any difference in soundquality, but I guess there might be a difference. Sndlib: http://ccrma.stanford.edu/software/snd/snd/sndlib.html mus_src is available in the file clm.c . libsamplerate: http://www.mega-nerd.com/SRC/ A third program is the original sinc-resampler from Julius Smith: http://ccrma-www.stanford.edu/~jos/resample/ I don't know how this one performs compaired to the other two though. --

20 years, 8 months

[linux-audio-dev] Best-performing Linux-friendly MIDI interfaces?

by Jay Vaughan

hi all, i'm currently working on a rather large project which i'd like to fully support under Linux .. it requires, however, a functioning MIDI sub-system. for this reason, i'd like to ask members of LAD to report on their experiences with using professional MIDI interfaces, such as (for example) the Motu MTP AV, Digidesign MIDEX-8, etc? what is the 'easiest' MIDI interface to get working under the average Linux kernel? what sort of experiences do folks have with getting MIDI working (on a programming level) using API's such as (but not limited to) ALSA, and MidiShare? for me so far, MidiShare seems to offer the most direct and usable approach .. while ALSA is wraught with complexity and dependencies which often seem out of control. i'd like to know what your experience, as developers, has been with getting a working MIDI subsystem under Linux ... -- ; Jay Vaughan

20 years, 8 months

[linux-audio-dev] [ANN] QjackCtl 0.2.16 released!

by Rui Nuno Capela

QjackCtl 0.2.16 is finally out! After laying around for a long time in the backyard (aka CVS:), the Qt front-end to the one-of-a-kind JACK audio server daemon is finally made public. Rejoyce! As one can read from the changelog: - ALSA sequencer client/port name changes are now properly detected on the MIDI connections widget (as noted by Chris Cannam. Thanks). - Long overdue transport buttons (rewind, backward and forward) finally landed onto the main control window, at last :). - Duplication (copy) of patchbay socket items was added. - Do not ever try to start the JACK server if there's one already found running, on which case the client-only mode of operation is then activated (as kindly suggested by Orm Finnendahl, thanks). - After several Mac OS X user requests, ALSA/MIDI sequencer support is now an option, otherwise detected at configure time and conditionally compiled in if, and only if, ALSA is found available (which has been a primordial assumption on Linux systems:). Ah, and that just makes for the blind inclusion of another backend driver option: coreaudio. - Actual OSS device selection menu now featured on setup dialog; these adds to the device selection button menus for the OSS driver settings. - Delayed geometry setup of windows upon startup was added as an optional workaround to subtle problems due to window decoration information not being available at window creation time on some window managers (as patch proposed by Dirk Jagdmann. Thanks). - Fixed some minor but rather old bug that was quitting the application abruptly, when one switches off the system tray icon while the main application widget is hidden. - Cancel is now an option when creating a new patchbay definition. - Context menus are finally littered with icons. - Minor configure and Makefile install fixes, as Debian and Mac OS X specialties. Also, install does the right thing with target file modes (thanks to Matt Flax and Ebrahim Mayat, for pointing these out). You can get away with it from the usual place: http://qjackctl.sourceforge.net/ http://sourceforge.net/projects/qjackctl Enjoy! -- rncbc aka Rui Nuno Capela rncbc(a)rncbc.org

20 years, 8 months

[linux-audio-dev] [ANN] QjackCtl 0.2.16 released!

by Rui Nuno Capela

20 years, 8 months

[linux-audio-dev] [OT] disaster redux

by Dave Phillips

Greetings: It has not been a good week. As I mentioned yesterday I swapped my hardware into an identical box as my original machine. Yesterday everything seemed to have returned to normal operation. I watched some movies, worked on some music, and so forth. Today I powered up the box, logged on to the net, downloaded the latest Csound CVS and started compiling. After a few minutes everything froze again, the machine was locked tight as a drum. I had to pull the plug to restart, but when grub came up my keyboard was frozen. I pulled the plug again and got my keyboard back after restarting. Now I'm running memtest again. I realized yesterday that I'd run it on only one RAM stick so I thought I'd better check again. However, at this point I'm starting to suspect a bad drive. But *two* bad drives in the system ?? As I mentioned in an earlier message, the machine failure occurred regardless of which drive I was using (RH9 on /dev/hdb, FC3 on /dev/hda). So I'm bummed again. Looks like it's time to bite the bullet and buy a whole new system. :( Best, dp

20 years, 8 months

[linux-audio-dev] Sending USB msgs to sound card through snd_usb_audio driver - how ?

by Jan Holst Jensen

Hi all. I am trying to control the settings of my EgoSys U2A sound card by sending it the same commands that I can see being sent to it when I am using the Windows U2A control panel. I naively thought that I could use libusb, but I cannot open interfaces on the sound card, because snd_usb_audio is using the device. Unloading snd_usb_audio releases the audio interface so I can claim it with libusb calls but that is hardly practical for changing settings occasionally. Are there any standard ioctl() calls in the snd_usb_audio driver that allows me to send messages to a USB interface, or any other way of doing this the civilized way - that is: through the driver ? Any pointers greatly appreciated. Cheers -- Jan Holst Jensen, Denmark __________________________________ Discover Yahoo! Find restaurants, movies, travel and more fun for the weekend. Check it out! http://discover.yahoo.com/weekend.html

20 years, 8 months

[linux-audio-dev] [ANN] Ambisonics plugins

by fons adriaensen

Hello, AMB-plugins-0.0.1 is a set of first order Ambisonics plugins I use with Ardour. Included in this first release are: - mono to B-format panner - stereo to B-format panner - B-format horizontal rotator - B-format to square decoder - B-format to hexagon decoder The dedoders feature proximity effect compensation and LF shelf filtering of the velocity components. More info is in the README. As usual to be found at: <http://users.skynet.be/solaris/linuxaudio> Enjoy ! -- FA

20 years, 8 months

[linux-audio-dev] [ANN] SkinDial QDial compatible class for eyecandy knobs

by Benno Senoner

The SkinDial class is written in Qt [1] provides flexible pixmap based dial/knob widget compatible with QDial [2]. The idea was to make it using Qt's QDial API so that apps (mainly audio apps) using this class can make use of eyecandy knobs without changing the code. (except for the constructor). screenshot: http://www.linuxsampler.org/misc2/skindial/skindialtest.png download: http://www.linuxsampler.org/misc2/skindial/skindial-0.0.2.tgz The full HTML documentation about the SkinDial widget is located in the docs directory. To show the possibilities of SkinDial widget we supplied an example program that displays various knobs. The example program is self explanatory. to compile and run the example program: qmake make.pro make ./skindialtest I'd like to thank Thorsten Wilms and Peter Shorthose for the 3D knob artwork rendered with Blender [3] If you make new knob pixmaps that you would like to contribute to SkinDial please let us know. Thanks Christian Schoenebeck for checking the doxygen API docs and various stuff. and the people on #lad and #qt channels for useful hints and inputs. The blender files and a README how to render the knob pixmaps are included in the knob_3d directory. larsl from #lad made a similar (with less options) widget for gtkmm. What do you think of making a web page that collects all those ready to use skinnable widgets so that users avoid reinventing the wheel (the knob :) ) all over again ? cheers, Benno http://www.linuxsampler.org [1] http://www.trolltech.com [2] http://doc.trolltech.com/3.3/qdial.html [3] http://www.blender3d.com

20 years, 8 months

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Linux-audio-dev