Linux-audio-dev December 2003

linux-audio-dev@lists.linuxaudio.org

67 participants
59 discussions

[linux-audio-dev] /dev/dsp0 --> /dev/dsp0L and /dev/dsp0R

by Fernando Ramirez

Hi. I need to know if there exists or if someone have coded a device driver that may split one stereo source input (/dev/dsp0) to two pseudo devices (something like /dev/dsp0L for left channel and /dev/dsp0R for right channel). I need this to split a 2 channel real time signal to two different applications than only accept a /dev/dsp? for input. I can do it if I install 2 soundcards on my machine and feed each separated mono source to each card but I feel that I am waisting one card. Any help pointing to a page with instructions in how to program a device (/dev/?) may help. Regards, Fernando _________________________________________________________________ MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*. http://join.msn.com/?page=features/virus

20 years, 4 months

[linux-audio-dev] [ANN] swh plugins release

by Steve Harris

http://plugin.org.uk/releases/0.4.3/ New plugins: Butterworth filter plugin (Alexander Ehlert) Impulse generator plugin (Andy Wingo) Delay plugin (Andy Wingo) Signal decay plugin (Andy Wingo) DJEQ plugin (me) Reverse Delay plugin (Jesse Chappell) Expander plugin (me, more-or-less untested) Vinyl sound plugin (me) Improvements: Improvements to the IIR filter code (Alexander Ehlert) Gain and delay correction factors for hilbert transformer (Fons Adriaensen) Make biquads internally float/douable at compile time (me) Changes to pitch scale (can't remember why, me) Added latency reporting ports to (most) plugins that need them (me) Updated README and auto* stuff (me) Changes to allow building under Win32 (Audacity Project) Fixed UID clash (me) - Steve

20 years, 4 months

[linux-audio-dev] portadio v19-devel and jack

by CK

hi, has anybody had any success using portaudio v19 to connect to jack (0.80.0 or 0.90.1) ? regards, x -- chris(a)lo-res.org Postmodernism is german romanticism with better http://pilot.fm/ special effects. (Jeff Keuss / via ctheory.com)

20 years, 4 months

Re: [linux-audio-dev] another kernel patch?

by Kjetil Svalastog Matheussen

>That's right. But, Paul and I have been working closely with this and >don't have much faith in the correctness of the 2.4 scheduler. Like >all non-trivial software components it has bugs, and getting them >fixed is difficult, if not impossible I dont quite understand the 2.4 scheduler, but I'm, eh, guessing that there is about 10% chance the following patch might fix the problem: kjetism@notam02 ~/linux/linux-2.4.23-rc1/kernel $ diff -u sched.c sched_g.c --- sched.c 2003-11-16 14:18:08.000000000 +0100 +++ sched_g.c 2003-12-03 09:31:32.000000000 +0100 @@ -180,6 +180,7 @@ if (p->mm == this_mm || !p->mm) weight += 1; weight += 20 - p->nice; + if(weight>999) weight=999; goto out; } If someone bothers, please explain why it wont, if it doesnt work, and if anyone knows. This is quite interesting. :) --

20 years, 4 months

[linux-audio-dev] Call for Works: ICMC

by tae hong park

Please excuse cross postings, and freely forward this message to anyone who might be interested. Thank you. Best, Tae Hong Park, ICMC 2004 Publicity Chair ---------------------------------------- Call for Works: ICMC 2004 The University of Miami is pleased to announce the general call for submissions to ICMC 2004, to be held 1-6 November in Miami, Florida USA. These documents, along with PDF submission forms and paper templates are posted on the ICMC 2004 web site at www.icmc2004.org. Best regards, Colby Leider, Chair

20 years, 4 months

[linux-audio-dev] new linux audio hardware company

by Patrick Shirkey

> http://www.museresearch.com >check the "technology->architecture" page (Flash). they are running >linux. they also run VST plugins. how? what's going on ... Just wondering if anyone asked them why they claim to be "license free"? -- Patrick Shirkey - Boost Hardware Ltd. Http://www.boosthardware.com Http://www.djcj.org - The Linux Audio Users guide ======================================== Apparently upon the beginning of the barrage, the donkey broke discipline and panicked, toppling the cart. At that point, the rockets disconnected from the timer, leaving them strewn around the street. Tethered to the now toppled cart, the donkey was unable to escape before the arrival of U.S. troops. United Press International Rockets on donkeys hit major Baghdad sites By P. MITCHELL PROTHERO Published 11/21/2003 11:13 AM

20 years, 4 months

[linux-audio-dev] another kernel patch?

by Paul Davis

while we're discussing various kernel security patches to facilitate easier access to SCHED_FIFO/mlockall, i have another idea for a patch that some people *might* like. a new system call. call it "switch_to()". takes a PID (actually, it needs some kind of TID), and does something very similar to sched_yield() except instead of giving up the processor to whatever the scheduler thinks is right, it yields to the specific process/thread. security: the target thread has to be using the same RT scheduling policy (FIFO or RR) as the initiating thread. this means that it can only be used to cause denial-of-service attacks that were already trivial (because SCHED_FIFO was already available to the initiating thread). this could be used to completely short-circuit the FIFO mechanism used by JACK in favor of completely deterministic, FS-lock-free system. when you add in stuff like this (from ingo, discussing NPTL): our kernel thread context switch latency is below 1 usec on a typical P4 box, so our NPT library should compare pretty favorably even in such benchmarks. We get from the pthread_create() call to the first user instruction of the specified thread-function code in less than 2 usecs, and we get from pthread_exit() to the thread that does the pthread_join() in less than 2 usecs as well - all of these operations are done via a single system-call and a single context switch. you end up with a truly superb architecture for the kind of thing we're doing with JACK already. however, note this comment from ingo as well, which i consider short-sighted, and is part of the reason for my thinking about switch_to(): M:N's big mistake is that it concentrates on what matters the least: useruser context switches. Nothing really wants to do that. And if it does, it's contended on some userspace locking object, at which point it doesnt really matter whether the cost of switching is 1 usec or 0.5 usecs, the main application cost is the lost paralellism and increased cache trashing due to the serialization - independently of what kind of threading abstraction is used. any thoughts? adding a syscall is a pretty trivial patch to create. --p

20 years, 4 months

[linux-audio-dev] mini Review: Re: [Jackit-devel] latest CVS commit

by Roger Larsson

On Monday 01 December 2003 20.48, Paul Davis wrote: > i'd appreciate test reports ASAP, so that out trusty release > technician (the very wonderful taybin rutkin) can get a new release > out in the near future. > alsa_driver.c driver->period_usecs = (jack_time_t) floor ((((float) driver->frames_per_cycle) / driver->frame_rate) * 1000000.0f); jackd/engine.c poll_timeout = (engine->control->real_time == 0 ? engine->client_timeout_msecs : engine->driver->period_usecs/1000); - - - if (poll (pfd, 1, poll_timeout) < 0) { Isn't this dangerous? * What happens if period_usecs < 1000? Well poll_timeout gets 0 since period_usecs is an uint64_t A poll with time out of zero will return immediately. OK? /RogerL -- Roger Larsson Skellefteå Sweden

20 years, 4 months

[linux-audio-dev] [OT] linux audio on PPCi

by vincent.touquet＠pandora.be

I am contemplating buying a laptop of some sort, to develop on. I was wondering how many of you are using an x86 laptop and how many are using a ppc laptop :) It looks to me as if Apples laptops are rock solid and don't suffer from buggy ACPI to start with. Or is this extra quality just a myth ? I know some applications are not ported yet to ppc and suffer from x86-isms, but that should be fixable I guess :) anyway, thanks for your input, v

20 years, 4 months

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Linux-audio-dev December 2003