Linux-audio-dev

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7516 discussions

by John Lazzaro

Hi everyone, The months fly off the calendar, and the time for the next IETF meeting arrives (in San Francisco later this month). Pick up the latest version of the MWPP I-D's at: http://www.cs.berkeley.edu/~lazzaro/sa/pubs/txt/current-mwpp.txt http://www.cs.berkeley.edu/~lazzaro/sa/pubs/txt/current-guide.txt Back at the end of the last meeting, I had predicted these documents would be "candidate Last Call" (the end of the writing process and the beginning of the vetting process ...), but alas, it was not meant to be. But I really think we're only a month away or so ... the things left to do are doable and not overwhelming. ------------------------------------------------------------------------- John Lazzaro -- Research Specialist -- CS Division -- EECS -- UC Berkeley lazzaro [at] cs [dot] berkeley [dot] edu www.cs.berkeley.edu/~lazzaro -------------------------------------------------------------------------

22 years, 8 months

[linux-audio-dev] Re: [linux-audio-user] Re: New LADSPA Hints (Was: [ANNOUNCE] tapiir-0.7.1)

by Mike Rawes

Think this needs to go to LAD too... --- Steve Harris <S.W.Harris(a)ecs.soton.ac.uk> wrote: > I think there was one more too, but I can't think what it was... I remember one about sidechains or something. I don't know what a sidechain is, though, I just recall seeing it somewhere :) > I agree AUDIO_RATE_CONTROL should be renamed. > > There was a suggestion on ardour-dev that a hint to say whether control outs > were supposed to be informative or a source of control data might help, > but I'm not sure about it. Not sure what 'informative' means here... what information do we get if we ignore the control data on the output? > Does someone want to reword these in a more meaningful way? If not I'l do > it, then you'l be sorry ;). I'll have a go :) (The LADSPA_IS_* things will need to be added too) /* Hint MOMENTARY indicates that that a control should behave like a momentary switch, such as a reset or sync control. LADSPA_HINT_MOMENTARY may only be used in combination with LADSPA_HINT_TOGGLED. */ #define LADSPA_HINT_MOMENTARY 0x40 /* Hint RANDOMISABLE indicates that it's meaningful to randomise the port if the user hits a button. This is useful for the steps of control sequencers, reverbs, and just about anything that's complex. A control with this hint should not result in anything too suprising happening to the user (eg. sudden +100dB gain would be unpleasant). */ #define LADSPA_HINT_RANDOMISABLE 0x80 /* Plugin Ports: Plugins have `ports' that are inputs or outputs for audio or data. Ports can communicate arrays of LADSPA_Data (for audio or continuous control inputs/outputs) or single LADSPA_Data values (for control input/outputs). This information is encapsulated in the LADSPA_PortDescriptor type which is assembled by ORing individual properties together. Note that a port must be an input or an output port but not both and that a port must be one of either control, audio or continuous. */ [...] /* Property LADSPA_PORT_CONTINUOUS_CONTROL indicates that the port is a control port with data supplied at audio rate. */ #define LADSPA_PORT_CONTINUOUS_CONTROL 0x10 - Mike > > - Steve > > > On Wed, 15 Jan 2003 18:13:35 +0000 > > Steve Harris <S.W.Harris(a)ecs.soton.ac.uk> wrote: > > > > > There have been a few suggestions recently, I'l try to summarise them > > > for comment. > > > > > > MOMENTARY. A hint to suggest that a control should behave like a > > > momentary switch, eg. on for as long as the user holds down the > > > key/mouse button/whatever. Useful for reset or sync controls for > > > example. Would be useful in the DJ flanger. Only applies to TOGGLED > > > controls. > > > > > > AUDIO_RATE_CONTROL. Hints than an audio control should/could be > > > controlled by a high time res. slider or control data, but shouldn't > > > be connected to the next audio signal by default. I can't think of any > > > simple examples off hand, but combined with MOMENTARY it could be used > > > for sample accurate tempo tapping. > > > > > > RANDOMISABLE. Hints that its useful/meaningful to randomise the port > > > if the user hits a button. This is useful for the steps of control > > > sequencers, reverbs, and just about anything that's complex. Allows > > > you to specify which controls can be randomised without anything too > > > supprising happening to the user (eg. sudden +100dB gain would be > > > unpleasent). __________________________________________________ Do You Yahoo!? Everything you'll ever need on one web page from News and Sport to Email and Music Charts http://uk.my.yahoo.com

22 years, 8 months

[linux-audio-dev] using kernel 2.5

by Paul Davis

bob mentioned issues with the serial port. i'd like to amplify that. if you are using a serial modem (COM1, COM2) etc, and you don't specify "EXPERIMENTAL" source support, you won't even have a chance to build the serial driver. once you do build it, it won't work for PPP (in my experience).

22 years, 8 months

[linux-audio-dev] Help wanted with audio app design

by Arthur Peters

I have been working on an audio processing/synthesis application that should have the power of Reason and Buzz plus the ability to be used effectivly in live proformance. Some of you may have read my earlier emails on this subject. I call it Voltage. The main features that I want but are not availiable in other software are: - Linux and Open-Source - the ability to route and process sequence data (MIDI like data). This would allow very powerful chordization and arpegiation. - the ability to create sequence loops in a flexible way (like Reason Matrix except without the limitations). I'd also like to be able to record/modify them live without stoping the playback. - the ability to control things in complex ways using scripting of some sort (maybe as a machine that is scripted to create certain sequence events) What I am looking for is someone to help me (an inexperienced software designer) design this program. That person don't nesseserily need to help code the program. I've desided I need help after multiple failed attempts. I think my current ideas are closer to a working design than past ones, but I don't want to code it then find out doesn't work (like I did last time round). If you are willing to help or have any tips or books I should read, etc. please email me. Thanks much. -Arthur -- Arthur Peters <amp(a)singingwizard.org>

22 years, 8 months

Re: [linux-audio-dev] Fwd: CSL Motivation (fwd)

by Stefan Westerfeld

Hi! On Tue, Feb 25, 2003 at 07:48:11PM +0200, Kai Vehmanen wrote: > Date: Tue, 25 Feb 2003 12:20:22 -0500 > From: Paul Davis <paul(a)linuxaudiosystems.com> > Reply-To: linux-audio-dev(a)music.columbia.edu > To: linux-audio-dev(a)music.columbia.edu > Subject: Re: [linux-audio-dev] Fwd: CSL Motivation > > >There are discussions on kde-multimedia about > >the future of Linux/Unix multimedia (especially sound). > >This is one of the most interesting messages. > > CSL is proposed primarily as a wrapper layer around existing APIs. as > such, it seems to me to have no particular merits over PortAudio, > which has the distinct advantages of (1) existing CSL also "exists". > (2) working on many platforms already and You're right about that one: CSL is not as complete as PortAudio w.r.t to portability. > (3) using well-developed abstractions. I do not believe that something is ever a "well-developed abstraction" by itself. Something is always a "well-developed abstraction" from something, designed to achieve a certain purpose. From the PortAudio homepage: | PortAudio is intended to promote the exchange of audio synthesis software | between developers on different platforms, and was recently selected as the | audio component of a larger PortMusic project that includes MIDI and sound | file support. This clearly states the purpose: if you want to write audio synthesis software, then you should use PortAudio. Then, I assume, the abstraction is well- developed. However, it does not state: "... is intended to play sound samples with sound servers easily. Or: ... is intended to port existing applications easily. Or: ... is intended to let the application choose its programming model freely." No. PortAudio makes a lot of choices for the software developer, and thus provides an easy abstraction. This will mean, however, that actually porting software to PortAudio will probably be hard (compared to CSL), whereas writing new software for PortAudio might be convenient, _if_ the software falls in the scope of what the abstraction was made for. > CSL was > written as if PortAudio doesn't exist. I don't know if this a NIH > attitude, or something else, but I see little reason not use consider > PortAudio as *the* CSL, and by corollary, little reason to develop Yet > Another Wrapper API. Well, I gave you some. The paper gives some more. Basically, CSL is intended for porting _most_ free software, whereas PortAudio is intended for portable synthesis software. I think PortAudio would benefit in _supporting_ CSL, rather than aRts for instance, because CSL is more generic ; once new sound servers (like MAS) come up, you need not patch PortAudio all the time, but just one place: a CSL driver. The same is valid for other meta-frameworks like SDL. > the only reason i was happy writing JACK was > precisely because its not another wrapper API - it specifically > removes 90% of the API present in ALSA, OSS and other similar HAL-type > APIs. I am glad you did write JACK, although back then I thought it was just another try to redo aRts (and we had some heated discussions back then), because some people seem to like it. If some people will like CSL, why not? If you added CSL support to JACK right now, you would never need to bother with any of the "sound server guys" like me again, because you could always say: "support CSL in your sound server thing, and then JACK will support your sound server". On the other hand, if you added JACK support to CSL, you could also mix the output of all of these "sound servers" into JACK, without endangering your latency properties. Cu... Stefan -- -* Stefan Westerfeld, stefan(a)space.twc.de (PGP!), Hamburg/Germany KDE Developer, project infos at http://space.twc.de/~stefan/kde *-

22 years, 8 months

[linux-audio-dev] LAD meeting - Linux Sound Night

by Frank Barknecht

Hallo, with the LAD meeting getting closer, I'm getting a bit curious about, what the plans are for the open "Linux Sound Night" on 15.3.? Will we hear some of you guys perform and Paul records it? ciao -- Frank Barknecht _ ______footils.org__

22 years, 8 months

[linux-audio-dev] 2.5 kernel recommendation ?

by Dave Phillips

Greetings: I need to investigate the 2.5.x kernel series. Is there a recommended version for audio work ? Low-latency patches ? Any special comments about the 2.5 series ? TIA! == Dave Phillips

22 years, 8 months

[linux-audio-dev] Why? call back API and other thoughts...

by Roger Larsson

On Thursday 27 February 2003 20:25, Tim Jansen wrote: > Did the other platforms use a callback-driven approach because it is a > superior API, or because it is the only way to have sound on > cooperative-multitasking OSes like MacOS <X and early Windows versions? > > Callback-driven APIs are much harder to use, especially with many existing > codecs and frameworks that have been written with a push API in mind. > I try to list some pro / con for call back and push APIs: push API: Pro: * simple to play a single file, basically a copy from source file to destination. Con: * hard to write plugins that way. Take a look at arts plugins. They all have a 'calculateBlock' = call back! Why? In a pure push model each processing step reads data from one file/pipe/device, processes it, pushes it to a file/pipe/device You get: * lots of threads/processes that are not optimally synchronized. Any thread is runnable when there are input available until the output is full. But that is not the important case, concider the case when the last processing steps output is almost empty (if it gets empty you will hear a click). How to prioritize it higher than all other threads? Should it always be higher? Suppose it is a mixer that has several inputs... Could be done by a super server that sets priorities depending on position in the line? This is not easy... * If plugins, with callback model, are used to build the application. Does it not make sense to build the whole application (audio part) the same way? There are some neat tricks that can be used, since the wrapper library can know where the destination is. * if the destination is in the same process, your output will end up somewere in your process memory. * On the other hand, suppose the destination is another application, it can allocate shared memory and let the output of your pluggin end up there. * If the output is destined to go to an audio board It could then give you a memory mapped hardware buffer instead of ordinary memory to avoid the final copy. (you will get different buffers on each process...) * if your output type does not match the input type of the destination, the library could automatically insert a converter/resampler either on your side or on the destination side (pick the one that gives less communication). * Can the destination change during the run? 1. Your application starts alone, output format matches one supported by hardware. => hardware buffers 2. Another application starts (suppose the device can have several destinations open at once - like SB Live!) => no change for your pluggin (but assume the format of this pluggin is not supported by hardware => in process buffer + automatic inserted convertion pluggin + hardware buffer) 3. Even more applications start... No more possible to output direct to hardware for all... suppose the library checks for matching data types - and the first application match perfectly! => the new application will get shared memory, your application will be changed to ordinary memory, these buffers will be mixed by an automatically inserted pluggin that outputs to the hardware buffer... 4. The new application ends. => hardware buffers again => your application/pluggin does not need to care. [No framework that I know of implements this today - especially not the automatic parts] With the push model your application needs to know about possible destinations, or treat everything as a file or shared memory. But how to handle the dynamic changes in the push model? Pipes, shared memory? It could also use a library that directs the produced buffer in the right direction (CSL?) - but it will be hard to eliminate extra copying. Note: Arts and the KDE multimedia framework does a lot of things right today. It even goes one step furter since it moves the pluggins, including input and output into one process - artsd. But currently it does not work perfectly together with applications using other frameworks. /RogerL -- Roger Larsson Skellefteå Sweden

22 years, 8 months

[linux-audio-dev] LAD Meeting at ZKM Karlsruhe 14-16 March 2003

by Dr. Matthias Nagorni

Hello, As announced earlier on this list, Frank Neumann and I are organizing a Conference of Linux Audio Developers at ZKM Karlsruhe. More information is available from http://www.linuxdj.com/audio/lad/eventszkm2003.php3 The list of speakers and talks is now complete and the webpage of the event has been moved to ZKM: http://on1.zkm.de/zkm/stories/storyReader$3027 Information on accommodation has been added as well. In addition to the speakers, the following LADers have registered so far: Rene Bastian Joern Nettingsmeier Jean-Daniel Pauget Kai Vehmanen Several other LADers have shown interest but not yet registered. If you want to register for the conference, please provide the following information: 1) Hardware you will be bringing (if any) 2) How long will you stay ? 3) Email address to which we can send last minute information Remarks: 1) It is not necessary to bring any hardware, but if you do so, it would be important for us to know because we need to plan the rooms, network cabling, power supply etc. 2) In addition to the talks, there is room for LAD internal discussion especially on Saturday morning and Sunday. We assume that on Sunday this will last until about 18.00. Some LADers will be around already on Friday morning (some even on Thursday afternoon), however we might still be busy with preparations for the talks. A live audio stream of the talks will be available for those who can not attend the event. Matthias -- Dr. Matthias Nagorni SuSE GmbH Deutschherrnstr. 15-19 phone: +49 911 74053375 D - 90429 Nuernberg fax : +49 911 74053483

22 years, 8 months

[linux-audio-dev] OT ReZound 0.7.0beta Release

by David Durham

ReZound aims to be a stable, open source, and graphical audio file editor primarily for but not limited to the Linux operating system. http://sourceforge.net/project/showfiles.php?group_id=5056 -- Notes: This release adds several new features and fixes a few bugs. Changes: - Added preliminary JACK support (the speed of and load on your computer will deterine how well this works) - Added a "Repeat Count" or "Repeat Time" when pasting from any clipboard - Added a "Balance" action which can change the balance or pan audio between two channels - Added some symmetry changing buttons and smoothing feature to the graph parameter widget - Added a "Recent Actions" under the "Edit" menu - When an audio I/O system is selected at configure time, ReZound will now fall back to OSS if the other is unavailable - Buffer size and buffer count settings can now be made without rebuilding - Made other minor cosmetic change, backend changes and bug fixes

22 years, 8 months

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Linux-audio-dev