Linux-audio-dev

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5 participants
7515 discussions

[linux-audio-dev] [CODE RFC] redefining sched_setscheduler using LD_PRELOAD

by Roger Larsson

Hi, (Jack O'Quin got me thinking about rt_monitor again - thanks!) This is an alternative to capabilities / SCHED_SOFTRR... I use my old rt_monitor * protects the system on RT overload * performs the actual setting of scheduler type * it does not even have to be visible for lusers! My old testprogram RT has been converted to a library fit for preloading. It works like this. As root start # rt_monitor As normal user start latencytest $ ./rts path/to/latencytest none 2 128 10 rts has two options -i do not raise the priority. -v be more verbose. * It does also limit the effective min/max range. Do also try (don't try this as root unless rt_monitor is running) $ ./rts path/to/latencytest none 2 1024 99 * In this case rt_monitor captures the process and renices it. (SCHED_OTHER + nice) BUGS: * better build and installation system * could ignore RT processes already running when rt_monitor starts * rt_monitor functionallity has not been reverified... * it can't lock memory :-( No PIDs in calls. * code that checks uid before using the redefined functions won't work (I have an modified latencytest) * client get stuck if there is no monitor running. /RogerL -- Roger Larsson Skellefteå Sweden

21 years, 11 months

Re: [linux-audio-dev] Fwd: [[NO] PATCH] cfq + io priorities

by Kjetil Svalastog Matheussen

Paul Davis: > >I guess this will be of interest to some of you... > >An even newer version has shown up on linux-kernel. > > its not clear how useful this really is. we know that the disk i/o > system can't keep up with realtime needs by definition - there has to > be a significant buffer between the disk and the RT audio thread. i'd > be suprised if it really helps any actual apps, because they've > already got this buffer in place, and the buffer hides the lack of > dedicated resource allocation on the part of the kernel. > Perhaps it would help programs that does everything inside one process, like snd. --

21 years, 11 months

[linux-audio-dev] Re: Programming resource question

by vanDongen/Gilcher

Excellent plan. Maybe I could contribute, since I was thinking along the same lines as well. My performance system is a pd pattern sequencer triggering csound, also geared to my personal setup, and I have been thinking on moving it to C as well. Parts are already coded in C as a pd external. Gerard On Thursday 13 November 2003 11:39, ian duncan wrote: > Well I'm actually making more of toolkit for do it yourself modular live > sequencing systems. So the idea is that one might use parts of it on PC, > port parts to Pic chips, or run parts coded in something like Csound or PD. > At the moment the whole thing is a gigantic Csound ensemble heavily > tailored around my own personal gear set up, so I haven't had to worry > about any low level stuff yet. But I would like to start modularizing it > and making it available to other people and platforms. It works well in > Csound, but file i/o is kluderific so I'd like to get that kind of stuff > going in C as well. > > Thanks, > Iain > > -- electronic & acoustic musics-- http://www.xs4all.nl/~gml

21 years, 11 months

[linux-audio-dev] Ann. Mammut V0.16

by Kjetil Svalastog Matheussen

Mammut will FFT your sound in one single gigantic analysis (no windows). These spectral data, where the development in time is incorporated in mysterious ways, may then be transformed by different algorithms prior to resynthesis. An interesting aspect of Mammut is its completely non-intuitive sound transformation approach. 0.15 -> 0.16 -Tiny source cleanup. -Upgraded the included sndlib i386-binary to latest version. This one includes jack-support. http://www.notam02.no/arkiv/src/ --

21 years, 11 months

[linux-audio-dev] Fwd: [[NO] PATCH] cfq + io priorities

by Roger Larsson

Hi, I guess this will be of interest to some of you... An even newer version has shown up on linux-kernel. /RogerL From: Jens Axboe -------------------------------- Hi, I've implemented IO nice levels in the CFQ io scheduler. It works as follows. A process has an assigned io nice level, anywhere from 0 to 20. Both of these end values are "special" - 0 means the process is only allowed to do io if the disk is idle, and 20 means the process io is considered realtime. Realtime IO always gets first access to the disk. Values from 1 to 19 assign 5-95% of disk bandwidth to that process. Any io class is allowed to use all of disk bandwidth in absence of higher priority io. Idle and realtime IO settings work as expected, but not much tuning has gone into making sure that the individual levels in-between work 100% as expected. It should be good enough for some testing at least, even if it has some holes. About the patch: stuff like this really needs some resource management abstraction like CKRM. Right now we just look at the tgid of the process. I've added two syscalls for setting and getting io priority. Don't consider this final or anything, it's just easy for testing. Patch has been tested on x86 and ppc, syscalls are also added for x86_64. I'm attaching the simple ionice tool. It's used as follows: # ionice -n20 bash starts a bash shell with realtime io. Beware that io level is inherited on fork, so any program you start from this shell will also run with realtime io. # ionice -n0 dbench 32 run some dbench thrasher, but only when disk is idle. Pretty straight forward :-) For really good results, you probably also want to set cpu nice level. Needless to say, a realtime io process can only submit io when it gets scheduled. Default IO priority for a new process is 10. Patch is against bk-current. -- Roger Larsson Skellefteå Sweden

21 years, 11 months

[linux-audio-dev] jack-freezes

by Florian Schmidt

Hi, this is a plea for help. I want to find out which factor makes jackd freeze on a client open, client close and client open again. So i would ask all of you using jackd and ardour or jack-rack to test for that behaviour and report the results along with system information back to this list. Maybe there is some constant factor.. I can observe this behaviour with both jack-rack and ardour. The procedure to make jack freeze is pretty much the same in both cases: jack-rack: start jackd start jack-rack close jack-rack start jack-rack again ardour: start jackd start ardour open a session in ardour close the session open it again My System info: dist: debian unstable [updated pretty recently] kernel: vanilla 2.4.22 kernel patched with LL, capabilities and Preempt alsa: 0.9.8 jackd: 0.89.12 i use: jackstart -R -d alsa -p 256 -n 2 ardour: Ardour/GTK 0.413.0 running with libardour 0.698.2 jack-rack: 1.4.3 Soundcard: terratec dmx xfire 1024 [snd-cs46xx] Regards, Florian Schmidt -- music: http://www.soundclick.com/bands/9/florianschmidt.htm

21 years, 11 months

[linux-audio-dev] ALSA OSS emulation in 2.6 kernel

by Benjamin Flaming

I'm not entirely sure whether this is the right place to be posting this or not. I've been having some strange issues with the OSS emulation in the 2.6 kernel. With each new kernel release, programs which use OSS have taken progressively longer to start up. Audacity now take about 20 seconds. There is also a 5-10 second delay from the time I hit "play" in Audacity to the time when the playback actually starts. Hydrogen takes a similarly long time to start up if I use OSS output. Finally, if I try to use the OSS MIDI driver for ZynAddSubFX, the entire system locks up - no Ctrl-Alt-Backspace, no Ctrl-Alt-Del, no Magic SysRq. I'm running the 2.6.0-test9 kernel on top of a Slackware 9.0 installation with an M-Audio Audiophile 2496 card. I have everything built into the kernel. The machine is an Athlon XP 1800+ with 256m memory. The output of dmesg after running an OSS application consists of repeated entries which all begin as follows: Debug: sleeping function called from invalid context at include/asm/semaphore.h: 119 in_atomic():1, irqs_disabled():0 Call Trace: [<c011ad4b>] __might_sleep+0xab/0xe0 [<c03727eb>] ap_cs8427_sendbytes+0x3b/0xd0 [<c0367952>] snd_i2c_sendbytes+0x22/0x30 [<c03667b6>] snd_cs8427_reg_write+0x36/0x80 [<c0366e26>] snd_cs8427_reset+0x56/0x240 [<c036763a>] snd_cs8427_iec958_pcm+0xea/0x170 [<c0370b23>] snd_ice1712_playback_pro_hw_params+0x73/0x80 [<c0343507>] snd_pcm_hw_params+0x267/0x2a0 [<c03435d8>] snd_pcm_hw_params_user+0x98/0x100 (followed by various functions, most of which begin with "snd_") I've posted the complete output of dmesg at: http://www.comevisit.com/NorthernSunrise/oss26/dmesg My kernel .config is at: http://www.comevisit.com/NorthernSunrise/oss26/config If there's anything I can do to help track this down, or if there is a better list for me to post this on, please let me know. |) |)enji

21 years, 11 months

[linux-audio-dev] last CFP: LCA2004 audio miniconf

by Conrad Parker

Hi, This is the last reminder for anyone interested in presenting at the audio mini-conference at Linux.Conf.Au, Monday January 12 2004. Submissions are due at the end of this week (Fri 31 Oct), details at: http://www.metadecks.org/events/lca2004/ It's turning out to be an excellent day of LAD hacking and jamming, with a full day of presentations lined up and an evening's playing at a local bar in the planning. The full schedule will be released next week. A mailing list has been set up for general discussions and info about the mini-conference, info for subscribing is at: http://lists.linux.org.au/listinfo/lca-audioconf To register for this mini-conference you MUST register for the main Linux.Conf.Au conference. Unfortunately audio-miniconf-only registrations are not available, sorry. Nevertheless you will not be disappointed: the main conference has four parallel tracks of tutorials and paper presentations running from Wednesday to Saturday, covering everything from programming VR applications to writing user-level device drivers; check it out and drool: http://lca2004.linux.org.au/programme.cgi Lastly ... if Tim Mayberry or Nick Mainsbridge could please drop me an email, or if anyone could give me current contact details for either of them, that would be much appreciated :) cheers, Conrad.

21 years, 11 months

[linux-audio-dev] Using Jack for "Control Volt" continued

by iainduncan＠telus.net

Sorry, forgot to ask a couple of things. Will Jack or other similar APIs allow passing of DC signal? If so, do we have to worry about speakers blowing up or do soundcards protect against DC? If not, can anyone tell me what the most CPU efficient way of modulating/demodulating a control signal might be? It occured to me that one could just use a very high frequency signal and have amplitude represent the DC control signal, requiring the receiver to use some sort of RMS amplitude tracking. This could also allow more than one control signal to be passed in one audio stream if we had several composite sines that were filtered apart again on the receiving end if the CPU demand of the filtering was less important than saving audio channels. Any thoughts, feedback, or redirection appreciated. Iain

21 years, 11 months

[linux-audio-dev] M-audio transit/ozone/MobilePre experiences?

by Mannr＠uwaterloo.ca

Does the M-audio MobilePre work with Linux? Earlier there was a 'beta' released (by Clemens Ladisch): http://sourceforge.net/project/showfiles.php?group_id=87777&release_id=1833… So does it work with the MobilePre? I'm planning to buy one soon if it does. Thanks, Richard

21 years, 11 months

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Linux-audio-dev