Linux-audio-dev December 2009

linux-audio-dev@lists.linuxaudio.org

87 participants
71 discussions

Re: [LAD] [LAU] Gui for convolution engine (jconvolver)

by hermann

Thanks Daniel I haven't look at the LV2 speck's, I have no Idea if it is possible or not. hermann Am Freitag, den 18.12.2009, 16:42 -0200 schrieb Daniel Roviriego: > Great job!! > I'm using right now and its a awsome tool!! > Is there any chance of building it as a lv2 plugin ? Is there > difficult ? > > Thanks a lot for sharing!! > > Daniel D2 Roviriego > > 2009/12/18 hermann <brummer-(a)web.de> > snip > > > > So with a free impulse-response all should be well? > > > > > > But why use a VST plugin under linux to apply an IR when > there is already > > > jconvolver present? > > > > > > *me wonders* > > > > > > Arnold > > > > > > > Hi Arnold, > > > > Some reasons come to this mind: > > > > A functional GUI. > > > > Better sound. > > > > Choice. > > > > I prefer the color yellow with my reverb's UI. > > > > VST plugins mean the world to me. > > > > > > Just some possible answers to your question. They are not > necessarily > > valid, true, or believable, they're just possible replies. > > > > HTH, > > > > dp > > > > Hi > > I have break out the jconv settings gui from guitarix and make > it available as > stand alone app. > It act as a (stereo) Host for jconv/jconvolver, to > create/save/load/run > configuration files for the use with jconvolver. > Indeed this Gui didn't cover the full advance of > jconv/jconvolver, but may be > the one or other found it useful. > > Additional jcgui provide master gain, left/right gain, > balance, left/right delay and > tone bass/middle/high controllers. > It's designed to use in realtime environment (jack) to > processing data, not for apply > to a file. > > get it here : > http://sourceforge.net/projects/jcgui/ > > have fun hermann > > _______________________________________________ > Linux-audio-user mailing list > Linux-audio-user(a)lists.linuxaudio.org > http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user >

15 years, 10 months

OSC: Divide & Conquer, or build a Stronghold?

by Harry Van Haaren

Hey all, I've been keeping myself busy lately, mostly with Python and OSC, and I'm using multiple clients/controllers to send messages to a sampler with an OSC interface. >From this experience it seems to me a good idea, to have a kind of "central" place where all Audio programs "Announce" thier OSC port & program name & version, so the linux-audio-desktop can be a little more "coherent" for lack of a better word.. ;-) We could create a kind of "Master OSC Host" which would keep track of which clients are running, and which ports they are using. This would be easiest to do if EACH client, would "register" itself on an agreed port. So if a client wants to read some information, they could query the "Master OSC Host" with a standardised set of questions about the current state of QTractor/Ardour/<Any OSC capable program>. This would mean that any program that wants to find out which Jack B:B:T or Frame were on or if there's been XRuns, wouldnt have to be a JACK client, because its been abstracted to the "Master OSC Host". I think this method would allow better inter program operability, as any "useful" information that one program could share, other could read. This would be most effective, if we also requested that programs followed a specific naming convention for features that each program has. EG: Save : /<prog_name>/save_state Load: /<prog_name>/load_state etc I'd like to get the communities feelings towards an initiative like this, feedback/criticism/opinions welcomed! -Harry Haaren

15 years, 10 months

Re: [LAD] Anyone have experience with OSS (3 or 4)?

by Kjetil S. Matheussen

Lennart Poettering: > > On Fri, 11.12.09 14:24, Kjetil S. Matheussen (k.s.matheussen(a)notam02.no) wrote: > >> After about 10 years of frustration, I'm a bit tired of alsa. >> >> Does anyone know if OSS supports proper software mixing? >> Is the alsa emulation working somewhat okay? >> Are there any problems configuring the machine to use more than one card? > > One should note that OSS on Linux is a dead-end. The latest two Fedora > releases have disabled kernel support for the OSS APIs by default, and > Ubuntu is expected to do this now too. (or already did?) > > Also, note that the big distributors have folks working on ALSA. OTOH > nobody who has any stakes in Linux supports OSS anymore or even has > people working on it. > No. Not providing mixing for all devices is a design fault in alsa. I'm going to install OSS as soon as I get time.

15 years, 10 months

Request: Native Linux vst Host

by Josh Lawrence

Hi devs, I would like to make a humble request: I would like to have a simple, stand-alone application for hosting native Linux vsts (.so). It would have very simple gui requirements (gtk?), be simple to use, and multichannel like ghostess is, able to load a plugin per channel. it would support jack midi. I would be willing to donate to such a project...I know $100 USD isn't enough to feed anyone's kids, but I would be willing to give that amount (today, to a registered paypal acct) to see this simple app written by someone who has a track record of doing good projects (Nedko immediate jumps to mind, but I'm sure there are others). is there someone who would like to do this? (energyXT hosts native plugins, as does renoise and ardour, but I just want an app that can be called up live. jost exists, but I've never been able to get it to play for more than a few minutes without crashing...maybe something else exists that I'm not aware of?) -- Josh Lawrence http://www.hardbop200.com

15 years, 10 months

Re: [LAD] Anyone have experience with OSS (3 or 4)?

by Kjetil S. Matheussen

Lennart Poettering: >> by itself plus providing low-latency performance (with mixing) when >> that is required. Leaving out mixing to third-parties, plus exposing >> a very complicated low-level API and a complicated >> plugin/configuration system (which probably has taken a more time to >> develop than implementing a proper mixing engine), has created lots >> of chaos. > > You cannot blame the ALSA folks that they didn't supply you a full > audio stack from top to bottom from day one with the limited amount of > manpower available. Just accept that their are different layers in the > stack and that different projects need to tackle them. And in the end > it doesn't matter which part of the stack has what name and is written > by whom. > Please read what I wrote one more time. I pointed out a very low-level API, no mixing, and a complicated configuration system. This causes software (programmed against ALSA) very often to be buggy, or simply not run because alsa doesn't do mixing. I'm certainly not blaming the ALSA foks for not doing enough work, (quite the opposite), but instead I'm pointing out some design desicions which I think have been quite disastrous. (As far as I know, mixing for all devices has never been on any TODO list in ALSA because they think it's wrong)

15 years, 10 months

Re: [LAD] Atomic Operations

by lieven moors

Here are the details... http://effocore.googlecode.com/files/EffoDesign_LockFree.pdf

15 years, 10 months

Re: [LAD] Anyone have experience with OSS (3 or 4)?

by Kjetil S. Matheussen

Lennart Poettering: > > On Thu, 17.12.09 13:52, Kjetil S. Matheussen (k.s.matheussen(a)notam02.no) wrote: > >> Mixing works just fine, even when using ASIO. Maybe you have to start >> the asio program first though, I don't know. But still, there's no >> reason why you shouldn't have a global option, lets say 256 frames >> 48000Hz, that everything mixes down to, and then software which needs >> hardcore low-level performance must obey to that setting. > > Uh, that's a great way to burn your battery. > > If you care about more than pro audio, then you want to dynamically > adjust the sleep times based on the requirements of the clients > connected. That means you cannot use fixed sized hardware fragments > anymore, but need to schedule audio more dynamically using system > timers. > > This in fact is where most of the complexity in systems such as > PulseAudio stems from. > Okay, I didn't know that. But this is still no reason why ALSA shouldn't take care of mixing/scheduling/etc. by itself plus providing low-latency performance (with mixing) when that is required. Leaving out mixing to third-parties, plus exposing a very complicated low-level API and a complicated plugin/configuration system (which probably has taken a more time to develop than implementing a proper mixing engine), has created lots of chaos.

15 years, 10 months

Anyone have experience with OSS (3 or 4)?

by Kjetil S. Matheussen

After about 10 years of frustration, I'm a bit tired of alsa. Does anyone know if OSS supports proper software mixing? Is the alsa emulation working somewhat okay? Are there any problems configuring the machine to use more than one card?

15 years, 10 months

Re: [LAD] Atomic Operations

by lieven moors

< However you can also use them to < implement circular FIFOs for example, which is a trick used all the < time in audio as well as in kernel programming. For anyone interested... The Effo libraries seem to have a fair choise of lock-free queue and ringbuffer implementations in the addon project: http://code.google.com/p/effoaddon/ But I have to admit that i find these concepts quite confusing...

15 years, 10 months

Atomic Operations

by Gabriel M. Beddingfield

Recently on this list, Paul referred to an "atomic integer swap" and an "atomic pointer swap." This was a new concept to me (and possibly others), and this e-mail shares what I've learned. If you access a variable from multiple threads -- even a built-in variable like 'int', it is important to control access to the variable with a mutex, semaphore, or an atomic operation. Alexander Sandler, on his blog, wrote a couple of good articles on the subject: "Do you need a mutex to protect an int?" http://www.alexonlinux.com/do-you-need-mutex-to-protect-int "Multithreaded simple data type access and atomic variables" http://www.alexonlinux.com/multithreaded-simple-data-type-access-and-atomic… The first article contains code that calculates a wrong answer on multiprocessor machines. I've attached a similar example that will even fail on a single-processor machine. There is a wealth of reading material on using Mutexes and Semaphores. However, information on atomic operations appears to be sparse and hard-to-follow. So, here's what I've found: + At the moment, there is no built-in support in C/C++ for atomic operations. You will need to use a library, compiler extension, or write your own in assembly code. + The GCC compiler has the built-in __sync_*() functions[1] that provide atomic operations. Note that the attached example is using this. + glib provides the g_atomic_*() functions[2]. + Qt 4 has the q_atomic_*() functions.[3] While they are accessible, they are /not/ a part of their stable, public API. + The next version of ISO C++ (code name c++0x) is expected to have support for atomic operations (E.g. the std::atomic<T> template) and memory barriers. It may even require that all built-in types be atomic. + In the x86 instruction set, these are usually implemented using the 'LOCK' instruction prefix.[5] When using atomic operations, perhaps the best advice I found is near the end of Sandler's second article: "When using atomic variables, some extra precautions have to be taken.... There is nothing that prevents you from incrementing value of the atomic variable with __sync_fetch_and_add() as I just demonstrated and later in the code doing same thing with regular ++ operator. "To address this problem, I strongly suggest wrapping around atomic functions and variables with either ADT in C or C++ class."[4] Peace, Gabriel [1] http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html [2] http://www.gtk.org/api/2.6/glib/glib-Atomic-Operations.html [3] http://doc.trolltech.com/4.3/atomic-operations.html See also the Qt header file QtCore/qatomic_i386.h, and its brothers. [4] http://www.alexonlinux.com/multithreaded-simple-data-type-access-and-atomic… [5] http://siyobik.info/index.php?module=x86&id=159

15 years, 10 months

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Linux-audio-dev December 2009