Linux-audio-dev April 2005

linux-audio-dev@lists.linuxaudio.org

107 participants
90 discussions

[linux-audio-dev] Other real-time options

by Jean-Marc Valin

Hi, After the debate regarding inclusion of realtime-lsm in the main tree, it seems like other approaches to unprivileged real-time have shown up. Both Con Kolivas and Ingo Molnar have come up with different (cleaner to the kernel developers) solutions. Both are described at: http://lwn.net/Articles/120024/ It seems like these solution have not been very popular yet, although I think they still have better chances of eventually being merged. I haven't tried Ingo's patch yet, but I can say that Con's SCHED_ISO_{FIFO,RR} (http://ck.kolivas.org/patches/SCHED_ISO/2.6.11.6-iso3.1.diff) works pretty good. Also, one nice feature that both approaches have is that you can set a limit on the amount of CPU a user RT task can use, preventing a user to lock up the machine. The way I see it, there are three important parts to a good solution: 1) Make sure no user can lockup the system with a "while(1);", so IMO realtime-lsm isn't the best solution (though I'm not strongly against) 2) Have per-user control, so that you can automatically restrict real-time tasks to only the person physically logged in. This would be important for a desktop configuration and would mean a distribution could enable this be default. 3) Making sure user tasks are lower priority that privileged tasks. Right now, Con's patch does 1 and 3, while Ingo's does 1 and 2 (though Con says Ingo's patch could also do 3). Would people here be happy with any of those and try to convince kernel developers that there's really a need for real-time (some still aren't convinced) and that one of these solution is acceptable? Jean-Marc -- Jean-Marc Valin <Jean-Marc.Valin(a)USherbrooke.ca> Université de Sherbrooke

20 years, 1 month

[linux-audio-dev] jack_process and pitch-shifting

by Olivier Guilyardi

Hi, In Jackbeat, I want to include support for realtime pitch shifting. One of the option is to use a quality resampler as libsamplerate's SRC_SINC_BEST_QUALITY converter. In the future, I may add support for libsoundtouch1 (http://sky.prohosting.com/oparviai/soundtouch/index.html). Can I do that in the jack process callback ? Or should I span a new thread and do the heavy job in there, ringbuffer'ing the result to the RT thread ? -- og http://xung.org/jackbeat

20 years, 1 month

[linux-audio-dev] Linux Audio Conference 2005 Live Audio/Video streams

by Joern Nettingsmeier

hi everyone! for those interested in linux audio development, the linux audio conference 2005 (http://lac.zkm.de) at the center for arts and media in karlsruhe/germany will be streamed live in both vorbis and theora formats. the conference takes place from april 21 - 24, with lectures and workshops from 11:00 to 18:00 UTC+2 every day and concerts in the evenings. i would like to invite you to join us, either in person (attendance to the conference is free) or remotely over the internet. for remote participants of the conference, there is a chat room #lac2005 on irc.freenode.net. a chat operator will be present in the auditorium in karlsruhe and will relay your questions to the lecturer and the local audience. papers and slides will be made available for download in advance if possible. information about the streams and how to watch them is at http://lac2005.zkm.de. huge kudos to the icecast, ogg, vorbis and theora developers and communites for their code and expertise! kind regards, jörn nettingsmeier on behalf of the linux audio community feel free to forward this message to interested parties.

20 years, 1 month

[linux-audio-dev] gettimeofday() realtime safe?

by Dave Robillard

Hi all, I need to know if gettimeofday (or one of the other standard time functions) is okay to use in a realtime jack thread. I can't find any information on the net about whether it's deterministic or not (or even how expensive it is). Problem is I have an event-based system that pushes events (from OSC/Midi) into a dequeue, which the audio thread runs through to execute. If you flood with events, too many need to be processed per block, the audio thread takes too long and you get dropouts. I'd like to be able to only process (non timestamped) events for x% of the time available to prevent this from happening; so I need to be able to determine how much time has been eaten by event processing so far. Is calling gettimeofday this many times in the realtime thread a wise idea? Cheers, -DR-

20 years, 1 month

[linux-audio-dev] Re: [ANN} Aeolus mailing lists and Wiki

by Juhana Sadeharju

>From: Fons Adriaensen <fons.adriaensen(a)skynet.be> > > aeolus-user(a)muse-sequencer.org > aeolus-dev(a)muse-sequencer.org I would like to have mailman lists with webpage subscription and with the digest option. But meanwhile please maintain downloadable list archives so that I may check what is going on there time to time. Oh yes, wiki is evil for offline downloading. I would like to curse the people who designed the wiki's page linking. Juhana -- http://music.columbia.edu/mailman/listinfo/linux-graphics-dev for developers of open source graphics software

20 years, 1 month

[linux-audio-dev] Soundcard available at LAC?

by Marije Baalman

Hi, as it seems I cannot get the RME sound card to work on my laptop, due to some strange PCMCIA problems, I'd like to ask once more... Does anyone, who is going to the Linux Audio Conference, have a multichannel soundcard (USB), that I might borrow to use on Thursday for my concert performance and rehearsals? I can offer a beer (or another drink) in return on the Linux Sound Night and my eternal gratitude, of course. Otherwise, you'll all have to do with a stereo version :) I'll be in Karlsruhe tomorrow evening (though not at the dinner, due to other obligations, maybe I'll join up later on in the evening, though), and have my rehearsal Thursday morning in the Kubus. So send me an email, or try and find me on Thursday morning :) see you soon! sincerely, Marije

20 years, 1 month

[linux-audio-dev] HDSP 9652 minimum buffer size

by Wolfgang Woehl

Paul, Thomas, What are the constraints for the HDSP 9652's apparent minimum buffer size of 64 frames? Is it the FPGA? Is it the firmware? Wolfgang

20 years, 1 month

[linux-audio-dev] debugging realtime issues with instrumented kernel

by Robert Jonsson

Hi, I recall someone (Lee?) mentioning something along the lines of using a recent kernel with Ingos patches to get feedback on realtime problems of your own code. It sounded very interesting! Now, I can't for the life of me find the message, if someone knows anything about this I would very much appreciate some more information, are there any links? Thanks in advance, Robert -- http://spamatica.se/musicsite/

20 years, 1 month

[linux-audio-dev] Re: linux-audio-dev Digest, Vol 19, Issue 33

by Ian Howard

Andres, and all, A very interesting idea, though here in West Africa, the main limitation in Linux adoption is not a lack of modem support, it is more to do with a lack of knowledge about Linux and open source, and too many aid and commercial organizations only touting or buying proprietary product. Here there are very few computers at home and even fewer people who can afford the incredibly expensive phone costs, that is the main reason that few modems are used here. Those who can, can afford hardware modems that supports Linux, as the monthly phone bill will well exceed. I was at an internet cafe recently, who had to shut-down because in one month their phone bill was over $350, twice their revenue. So, I think that though this is a solid idea, and that it might have application in some developing countries, here in West Africa modems and phone lines are the last choice due to their expense. Ian On Mon, 2005-04-18 at 12:09 -0400, linux-audio-dev-request(a)music.columbia.edu wrote: > Send linux-audio-dev mailing list submissions to > linux-audio-dev(a)music.columbia.edu > > To subscribe or unsubscribe via the World Wide Web, visit > http://music.columbia.edu/mailman/listinfo/linux-audio-dev > or, via email, send a message with subject or body 'help' to > linux-audio-dev-request(a)music.columbia.edu > > You can reach the person managing the list at > linux-audio-dev-owner(a)music.columbia.edu > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of linux-audio-dev digest..." > > > Today's Topics: > > 1. Re: crazy idea... (Andres Cabrera) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 18 Apr 2005 11:14:30 -0500 > From: Andres Cabrera <andres(a)geminiflux.com> > Subject: Re: [linux-audio-dev] crazy idea... > To: "The Linux Audio Developers' Mailing List" > <linux-audio-dev(a)music.columbia.edu> > Message-ID: <1113840867.3663.5.camel(a)localhost.localdomain> > Content-Type: text/plain; charset=UTF-8 > > Hi, > > It would be fantastic if that crazy idea could be done! In my opinion a > big limitation for greater adoption of linux on third world countries > like Colombia where a broadband connection is still a luxury, is the > limited modem support. > I recently tried to find linux compatible modems and it was impossible > (or too expensive -around US$50) in the local market, so I had to ask my > brother (who lives in the US) to get me one from ebay which can cost > around US$15 incl. shipping. > > Cheers, > Andrs > > > On Sat, 2005-04-16 at 02:04, Peter Zubaj wrote: > > slmodem is for SmartLink modems (it has this in licence) and it contans > > binary part - it can not run on PPC or other processors. > > I've seen somewhere project to write software modem, but it was not > > finished and abandoned. > > > > Peter Zubaj > > > > torbenh(a)gmx.de wrote: > > > > >On Thu, Apr 14, 2005 at 03:27:02PM -0700, Stephen Hassard wrote: > > > > > > > > >>Hey Lee, > > >> > > >>I was thinking about this a little bit and it's probably easier than it > > >>sounds. > > >> > > >>I thought that Alsa already supported MC97 based AMR modems? It looks > > >>like it does with the SND_INTEL8X0M module .. > > >> > > >>Also, you wouldn't have to worry about injecting stuff into the > > >>networking layer since modems are just character devices in linux. > > >> > > >>The only real part would be the DSP stuff. Their might be some other > > >>projects to do this kind of stuff already .. > > >> > > >> > > > > > >the slmodemd is already a user space app. > > >and it has an alsa mode already. though it did not work when i tested > > >it. > > > > > > > > > > > >>later, > > >>Steve > > >> > > >>Lee Revell wrote: > > >> > > >> > > >>>I had the idea the other day that you could theoretically implement a > > >>>Winmodem driver as a JACK client. All you would need is an ALSA driver > > >>>that exposes the hardware part of the modem as a sound card, a mechanism > > >>>to inject the resulting bits back into the kernel networking layer, and > > >>>the DSP knowledge to implement a software modem... > > >>> > > >>>This is almost completely pointless, but might be an interesting CS > > >>>project. > > >>> > > >>>Lee > > >>> > > >>> > > >>> > > > > > > > > > > > > > > > > > > > > ------------------------------ > > _______________________________________________ > linux-audio-dev mailing list > linux-audio-dev(a)music.columbia.edu > http://music.columbia.edu/mailman/listinfo/linux-audio-dev > > > End of linux-audio-dev Digest, Vol 19, Issue 33 > *********************************************** -- Ian Howard IESC/Geekcorps Mali "les volontaires de l'informatique" coordinateur de programme -------------------------------------------------- geekcorps (http://maligeekcorps.org) ihoward(a)geekcorps.org bureau/office: +223 221 49 43 mobile: +223 640 30 40 Porte 1085, Rue 240, Bamako, Mali

20 years, 1 month

[linux-audio-dev] crazy idea...

by Lee Revell

I had the idea the other day that you could theoretically implement a Winmodem driver as a JACK client. All you would need is an ALSA driver that exposes the hardware part of the modem as a sound card, a mechanism to inject the resulting bits back into the kernel networking layer, and the DSP knowledge to implement a software modem... This is almost completely pointless, but might be an interesting CS project. Lee

20 years, 1 month

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Linux-audio-dev April 2005