Linux-audio-dev July 2005

linux-audio-dev@lists.linuxaudio.org

72 participants
64 discussions

[linux-audio-dev] FM, Phase Modulation and The Wiki

by Jens M Andreasen

Hi! I am trying to correct some factual errors in wikipedia regarding FM synthesis (aka phase modulation.) The page in qustion is here: http://en.wikipedia.org/wiki/Frequency_modulation_synthesis My current corrections are in italics. Further corrections appreciated I am currently looking at the Casio section near the end (regarding phase distortion.) Wasn't this technique developed way back in the 60's by french academics? mvh // Jens M Andreasen (and yes, somebody ought to rewrite the whole page from scratch :)) --

19 years, 8 months

[linux-audio-dev] [WIP] hdsposc

by Mario Lang

Hi. Since I finally ordered my Multiface, I also started to write a small program which I am going to need since hdspconf and hdspmixer are both GUI only. The idea: hdsposc will offer the RME mixer and the metering functionality via OSC. Why do I write this mail? I'd like to know if someone else could also make use of this tool. If so, I'd like to hear your input what you'd want to exactly do with it. If no one responds, I'll save coding time by ONLY implementing the Multiface (since thats what I can test) and probably not polish it much, since what I need is probably very basic. Oh, and BTW, during coding of hdsposc a question arose: Is it recommended practice to immediately close a hwdep device again after performing a single operation, or would it be OK to leave the hwdep handle open during runtime and only close it again on program shutdown? -- CYa, Mario

19 years, 8 months

[linux-audio-dev] my first LADSPA plugins

by Artemio

Hello all! I am happy to tell you that I've finished my very first plugins. I would like to thank all those who helped me over here to get started and to Tim who kindly provided free plugin IDs. There are four plugins, each with mono and stereo variant: - Clipping Booster - boosts/clips the signal after a non-linear amp - Noisifier - applies AM to the signal with a variable noise source - Non-linear Amplifier - amp with 6 transmission curve types (round/parabolic/sine/etc.) - Variable Noise - generates white/stepped/shot noise Download plugins/docs: http://artemiolabs.com/software/wasp/ Online docs: http://artemiolabs.com/software/wasp/docs/WASP.html Comments and suggestions are very welcome. But please don't be cruel because this is my first serious C coding and very first DSP experience! I've tested the plugins thoroughly in many hosts, I hope they work for you too and will be useful. Artemiy.

19 years, 8 months

[linux-audio-dev] linking multiple .o plugins into a single .so library

by Artemio

Hello all! I have a question regarding linking multiple plugins into a single library. if I do: $ ld -shared -o plugins.so plugins/*.o - then ld complains that g_psStereoDescriptor and g_psMonoDescriptor as well as _init and _fini functions are duplicate and does nothing. If I try: $ ld -shared -z muldefs -o plugins.so plugins/*.o - this does some wizardry on changing the duplicate functions names (_init and _fini) and in the host only the last plugin in the .o files list is seen. As I understand I cannot change the names of _init and _fini because these are standard for libraries (or not?) and names of g_psStereoDescriptor and g_psMonoDescriptor are standard for a LADSPA plgin (or not?)... But what should I do? Or is is better to keep the plugins in separate .so files? Thanks very much! Artemiy.

19 years, 9 months

[linux-audio-dev] So what are these "spufs" anyway?

by Jens M Andreasen

Article about Linux and the upcoming "Cell" processor at Linux Devices: http://www.linuxdevices.com/news/NS6219524044.html Link at the end of article to IBM: http://www-128.ibm.com/developerworks/power/library/pa-cell/?ca=dgr-lnxw09S… --

19 years, 9 months

[linux-audio-dev] best soundcard revisited

by Aaron

Hi all, I am busy writing a grant proposal and I am now pricing audio/computer equipment. I plan to have all the computers dual booting lin/win and want the best quality sound card I can get that will run on both lin and win with the least trouble and the most bang for the buck. I don't need multitrack recording necessicarily. This issue has popped up on the list before but I would like to get a fresh veiw on this from the list. Thanks Aaron

19 years, 9 months

[linux-audio-dev] LADSPA plugin IDs needed

by Artemio

Hello all! I am writing to ask if Richard Furse is in vacation and if there is an alternative method of getting unique IDs for my plugins. I sent a mail to ladspa(a)muse.demon.co.uk about 3-4 days ago, but haven't got any reply yet. I already created four plugins, each with mono and stereo variants, so I need 8 IDs to publish the plugins. And I already know that there will be 3-4 more plugins so I'd need a range of 14-16 ID's actually... So what should I do? Thanks a lot guys! Yours, Artemiy.

19 years, 9 months

[linux-audio-dev] Re: desktop audio resumed

by Kjetil Svalastog Matheussen <k.s.matheussen＠notam02.no>

Lee Revell: >> It was in response to problems such as these that I began work on a >> half-kernel, half-userspace system for emulating OSS devices. It's been >> a while since I've done anything with it but if there's any interest in >> such a system I could put my code (such as it is) up for download. > > No!!! That's exactly the wrong approach, it will only encourage > applications to use the OSS API. Do you really still want to be using > the same ancient binary-only flashplayer/realplayer plugin for 5 more > years? > > Why don't you ask the Skype developers when they plan to support ALSA? > Or figure out why it crashes with aoss? > I strongly disagree with you about this. Ross approach sounds like whats needed. The OSS API is easier to understand and leads to less bugs and less programming time. For programs like SKYPE, mediaplayers and other types of non-realtime-sound applications, I really think programmers should go for OSS instead of accessing ALSA directly. And, as mentioned before, ALSA is linux only (except for alsa 0.5 which was partly used in older versions QNX I think).

19 years, 9 months

Re: [linux-audio-dev] Compiling ALSA. Was: Sending USB msgs to sound card...

by Jan Holst Jensen

> > sourceforge. Can't get it to compile - it misses a > > ./configure script when running "./build config". > > Run the cvscompile script, or see the INSTALL file. > > The patch should work with the 1.0.9b release, too. Know it's been a while, but I have finally had some time on my hands to look at it again. I used a CVS snapshot from 2005-06-20 and the patch applies cleanly. alsa-driver/ builds and installs without trouble. However, alsa-lib won't build - with and without the patch. Using a CVS snapshot as of today, alsa-lib still refuses to build - and the patch also fails :-/. The patch is not in CVS (yet?) ? At least I haven't found any references to IFACE_USB_CTRL in alsa-kernel/include/asound.h. The alsa-lib build error is gcc -shared .libs/conf.o [...]-Wl,libasound.so.2 -o .libs/libasound.so.2.0.0 /usr/bin/ld: .libs/libasound.so.2.0.0: undefined versioned symbol name snd_pcm_hw_params_get_buffer_size_max(a)ALSA_0.9 /usr/bin/ld: failed to set dynamic section sizes: Bad value collect2: ld returned 1 exit status When I try to do the steps in cvscompile manually I get the following: jhje@flyvehest:~/alsa-cvs/alsa-lib$ automake --foreign --copy --add-missing src/Makefile.am:21: invalid unused variable name: `AM_LDFLAGS' Must be something obvious since the error is the same between the two snapshots (?). Cheers -- Jan ____________________________________________________ Yahoo! Sports Rekindle the Rivalries. Sign up for Fantasy Football http://football.fantasysports.yahoo.com

19 years, 9 months

Re: [linux-audio-dev] desktop audio resumed

by Jan Holst Jensen

--- Lee Revell wrote: > So all the advice needed is "make sure you use the > latest ALSA". Just got dmix configured, inspired by this thread. It is really simple using the steps in http://alsa.opensrc.org/index.php?page=DmixPlugin. Even Flash-stuff in Firefox behaves nicely now (just start Firefox with "aoss firefox")! Have I understood it right that ALSA 1.0.9 and later sets up dmix per default, also for aoss, so that you can play aoss stuff and multiple alsa streams simultaneously ? That sounds exactly like what we need to get stuff to "just work". Cheers -- Jan __________________________________ Do you Yahoo!? Yahoo! Mail - Helps protect you from nasty viruses. http://promotions.yahoo.com/new_mail

19 years, 9 months

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Linux-audio-dev July 2005