Linux-audio-dev

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3 participants
7541 discussions

[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

22 years, 3 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

22 years, 3 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

22 years, 3 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.

22 years, 3 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

22 years, 3 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

22 years, 3 months

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

by iainduncan＠telus.net

Sorry if this is the wrong place, please tell me where to ask if it is. I'm wondering whether it will be possible, ( or if anyone is doing something similar ) to use Jack to pass control signals between audio apps. I think it would be extremely useful to be able to send the equivalent of PD wires or Csound krate variables back and forth between different apps as if the were Control Voltages, allowing the functionality of outboard CV modulars with tools from more than one family. I am also interested in the possibility of extending the same to outboard hardware, ie having control signals generated and transformed between apps and then sent out as actual CV signals to outboard modular components. I've been working on a real time step sequencer in Csound that allows sophisticated real time sequencing of control signals in the fashion of step sequencers and would like to know how I can perhaps integrate my work with others. I am really just a Csound programmer, and not a C developer ( yet ) so please excuse me if this is noise on the list. ; ) Also, does or will Jack allow signals to be lower bit depth or sample rate when full audio resolutions is not necessary, or will it always be full audio? I'm just thinking that maybe it would be good to be able to pass control signals with less bandwith, but of course that would introduce other complications. Is there any limit to the number of ins and outs Jackable? I guess to make modular synthesis between various apps one would start using a *LOT* of them. Thanks, Iain Duncan

22 years, 3 months

[linux-audio-dev] linux-kernel comments on POSIX capabilities support (fwd)

by Kai Vehmanen

Crossposting from jackit-devel to here... ---------- Forwarded message ---------- From: Kai Vehmanen <kai.vehmanen(a)wakkanet.fi> Subject: [Jackit-devel] linux-kernel comments on POSIX capabilities support Not too encouraging.. :( http://kt.zork.net/kernel-traffic/kt20031101_239.html#3 Quoting Albert Cahalan: ""The authors of our code seem to have given up and moved on. Nobody cleaned up the mess. Is it any wonder the POSIX draft didn't ever make it beyond the draft state?"" -- http://www.eca.cx Audio software for Linux!

22 years, 4 months

[linux-audio-dev] Re: Dev Music

by Pedro Moreal

>You might want to take a look at some of the graphical sound systems, >then. For example Pd (www.pure-data.org) is very easy to set up and >yet very powerful. You could use some of the Pd extensions to create >images of sound or the other way around. GEM is very easy to get >started with, if you have an OpenGL enabled card. For reading from a >TV card (or webcam) PDP is nice. I will look your suggestions. Very thanks! >This is directly programming the soundcard hardware. Do you really >want to do that? In my opinion this could be too difficult for your >pupils, if they don't have a certain background with that. But I may >be wrong. Anyway, using something like Pd will still be a good >>experience, because you get to see the whole picture of sound >generation better. The Pd author Miller S. Puckette also uses Pd to >teach sound synthesis and such. See his upcoming book at >http://www.crca.ucsd.edu/~msp/techniques.htm Hummm... directly soundcard hardware??!!! :( I will test your suggestions, but... I just wanna one program can show one image when pupil play one C note ,or G, etc and maybe control intensity of color with gain of sound. Something that it can select colors, pictures and texts using pure notes played with guitar or harmonic or other instrument. Is not to produce images but to *select* images or colors (images too) or text. Is it programming direclty in soundcard hardware? Not exist some librariy done can make this job (send to my program one pure value represent the note played)? I don't want Midi sound, it is very horrible to hear :) I know, I want much. But to our project is very interesting give for pupil the possibily to choose the relation note/color/picture or note/word. Is it very hard? For me all in this audio-world is hard because I don't have much notion about hardware programming (I'm just one database specialist), but if it's possible just using done values sent of the one library, all is ok. >I'd be glad to hear about your experiences. :) You will hear my screams!! >I think, you will need some mathematics, but nothing too complicated. >A bit of trigonometry is very useful in computer sound but you can get >far with knowing just muliplication and summing. At least in Pd, that >is. >ciao So... very very very thanks for your atention. []'s Alexander

22 years, 4 months

[linux-audio-dev] Dev Music

by Alexander Franca Fernandes

Hi! Please, be patience with my horrible english. I want make one program that can get notes/sounds and put out in screen images. I don't have any idea how I can do this. What language, what libraries, and I don't have any Idea how work /dev/dsp. What the first step? This project is for pupils of school where I work. We want do one project where pupils can do more with computer. Actualy in majority of schools the work in computer just resume using this machine for make "office" jobs. The comunication, expression, human knowledge, is "puted" out. So... we want try destroy some concepts using computer with people between 12 and 16 yeas old. This program we want build is just one part of our project. So... if I can do this program, need I learn a lot of mathematic and fisic? Or I can do this just with knowlegde about programer. Thanks for any help! Alexander

22 years, 4 months

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Linux-audio-dev