Linux-audio-dev July 2011

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Faust MIDI?

by Carlo Capocasa

Hi, is it possible to send and receive MIDI with a FAUST program? Carlo

13 years

RDF libraries, was Re: [ANN] IR: LV2 Convolution Reverb

by Chris Cannam

On 23 February 2011 22:11, David Robillard <d(a)drobilla.net> wrote: > SLV2 is now based on two new libraries: Serd (RDF syntax) and Sord (RDF > store). Both are roughly 2 thousand lines of C, solid and thoroughly > tested (about 95% code coverage, like SLV2 itself). Serd has zero > dependencies, Sord depends only on Glib (for the time being, possibly > not in the future). Can you point me at the API or code? I couldn't see it in a quick browse on your SVN server. I have a library (Dataquay, http://code.breakfastquay.com/projects/dataquay -- preparing a 1.0 release of it at the moment, so if anyone wants to try it, go for the repository rather than the old releases) which provides a Qt4 wrapper for librdf and an object-RDF mapper. It's intended for applications whose developers like the idea of RDF as an abstract data model and Turtle as a syntax, but are not particularly interested in being scalable datastores or engaging in the linked data world. For my purposes, Dataquay using librdf is fine -- I can configure it so that bloat is not an issue (and hey! I'm using Qt already) and some optional extras are welcome. But I can see the appeal of a more limited, lightweight, or at least less configuration-dependent back-end. I've considered doing LV2 as a simple example case for Dataquay, but the thought of engaging in more flamewars about LV2 and GUIs is really what has put me off so far. In other words, I like the cut of your jib here. Chris

13 years, 8 months

a *simple* ring buffer, comments pls?

by James Morris

just wondered if any more-experienced-than-i devs might comment on this. written in c for c (obviously). i realize it's not portable outside of GNU GCC (regarding the GCC atomic builtin funcs __sync_***). meant for a single reader thread and a single writer thread. comments regarding thread safety very much welcome. thanks in advance. james. #include "rng_buf.h" /* only prototypes the public functions and typedefs the struct */ #include <stdlib.h> #include <string.h> #include "debug.h" struct _RingBuffer { size_t count; void** buf; void** bufend; void** volatile w; void** volatile r; }; RngBuf* rng_buf_new(size_t count) { size_t sz = 1; RngBuf* mb = malloc(sizeof(RngBuf)); if (!mb) { return 0; } for (sz = 1; sz < count; sz <<= 1) ; mb->buf = calloc(sz, sizeof(void*)); if (!mb->buf) { free(mb); return 0; } mb->count = sz; mb->bufend = mb->buf + mb->count - 1; mb->w = mb->buf; mb->r = mb->buf; return mb; } void rng_buf_free(RngBuf* mb) { free(mb->buf); free(mb); } size_t rng_buf_write(RngBuf* mb, const void* data) { if (__sync_bool_compare_and_swap(mb->w, 0, data)) { if (!(__sync_bool_compare_and_swap(&mb->w, mb->bufend, mb->buf))) __sync_add_and_fetch(&mb->w, sizeof(void*)); return (size_t)1; } return (size_t)0; } void* rng_buf_read(RngBuf* mb) { void* data; if ((data = __sync_fetch_and_and(mb->r, 0))) { if (!__sync_bool_compare_and_swap(&mb->r, mb->bufend, mb->buf)) __sync_add_and_fetch(&mb->r, sizeof(void*)); return data; } return NULL; } void rng_buf_reset(RngBuf* mb) { /* needs work */ mb->r = mb->w = mb->buf; }

13 years, 9 months

Yoshimi Midi Learn: 1st testing release

by louis cherel

Hello everyone, Every one knows Yoshimi, the fork of ZynAddSubFx. One thing was lacking to yoshimi to be perfect: to be nearly fully controlled by midi controls ( no OSC, sorry ). ZynAddSubFx had possibilities to control a few parameters with complicated NRPN, Yoshimi recently had ( in the test versions ) some features too. But now I'm proud to announce you the work of licnep ( not me, I'm just a bug reporter ) who made the "midiLearn" function for yoshimi. It's not stable for now because it's recent, and not full, but here are the present features: * Control System effects, Part Insert Effects * Master/Part Volume, Pan, System Effect Sends * Most of ADsynth parameters * Add/Remove controller * detect the channel and the number * reset the knob ( its position ) I think it's a feature that's very useful and could help many yoshimi/zyn users. To use it, that's simple: connect your controller to yoshimi, right-click on a blue knob ( yellow are ones which are not supported for now ) and click "midi Learn" move your controller, it detects automatically the controller. To see and modify controllers, go to the Yoshimi> MIDI controllers menu. To erase midi control of a knob, simply right click on it and click on "remove midi control" Here is the gitHub repository: https://github.com/licnep/yoshimi To download and install it, follow the explications link ( gitHub ): https://github.com/licnep/yoshimi/wiki/How-to A light page to understand how to control others not implemented controllers: https://github.com/licnep/yoshimi/wiki/Source-code Pages to follow the news of the project: Facebook: https://www.facebook.com/pages/Yoshimi-midi-learn/224823617534934 Twitter: http://twitter.com/#!/YoshimiMIDI So if you're interrested, all bug requests are deeply recommended. Cheers, Louis CHEREL.

13 years, 9 months

[ANN] International Conference on Spatial Audio, Nov 10-13 2011, in Detmold, Germany

by Jörn Nettingsmeier

hi *! sorry for the slightly off-topic post, but since spatial audio has been a frequent topic lately, i think some people here might be interested. linux or FLOSS won't be exactly in the limelight, but yours truly will make sure there are at least 2-3 boxes with your favourite OS and audio tools humming along in various places. oh, and you might come early and watch a few high-end mixing consoles boot - the startup screen will bring tears to your eyes (as will the price tag, unfortunately :) unfortunately, there will have to be an admission fee, which we haven't decided on yet. but we're trying to keep it reasonable. don't shout at me when it turns out to be a bit more costly than LAC, though... jörn *.* ICSA 2011 - International Conference on Spatial Audio November 10 - 13, Hochschule für Musik, Detmold Organizers: Verband Deutscher Tonmeister (VDT), in cooperation with Deutsche Gesellschaft für Akustik e.V. (DEGA), and European Acoustics Association (EAA). Contact/Chair: Prof. Dr.-Ing. Malte Kob Erich-Thienhaus-Institut Neustadt 22, 52756 Detmold Mail: icsa2011attonmeister.de Phone: +49-(0)5231-975-644 Fax: +49-(0)5231-975-689 Summary: The International Conference on Spatial Audio 2011 takes place from November 10 to 13 at Detmold University of Music. This expert‘s summit will examine current systems for multichannel audio reproduction and complementing recording techniques, and discuss their respective strengths and weaknesses. Wavefield synthesis systems, a higher-order Ambisonics array, as well as 5.1/7.1 installations in diverse acoustic environments will be available for comparative listening tests during the conference. Structured plenary talks, paper and poster sessions will revisit fundamentals and present latest research. A series of workshops will be dedicated to practical implementations of spatial sound capture and playback methods, and their esthetic and psychoacoustical implications for music perception. Concerts that include music specially arranged for the conference will let you experience various spatial sound systems in "live" conditions. Call for papers and music: Your contributions are welcome, either as presentations, posters, or workshops. Submissions will undergo a review process, and accepted contributions will be published in the conference proceedings. The conference language is English. We are planning structured sessions on the following topics: * Multichannel stereo * Wave field synthesis * Higher-order Ambisonics / spherical acoustics * 3D systems * Binaural techniques An additional session will be dedicated to related miscellaneous contributions, such as hybrid systems and perception/evaluation of spatial music reproduction.

13 years, 10 months

excellent overview article on realtime audio programming

by Paul Davis

Ross Bencina is the author of AudioMulch and has been extremely involved in PortAudio, ReacTable, and other projects. His new article on realtime audio programming is a MUST read for anyone new to the area, and worth reading as a reminder even for experienced developers. http://www.rossbencina.com/code/real-time-audio-programming-101-time-waits-… I'm off to count how many violations Ardour contains ... --p

13 years, 10 months

Testdriven development with JACK?

by Adrian Knoth

Hi! This question could have also been asked on jack-devel, but since LAD probably has a broader audience: I recently started hacking on a jack-driven matrix mixer (goals so far: GUI, maybe network controls (OSC?), maybe LV2 host), and I wonder if there are "frameworks" for test-driven development, so I can come up with unit and acceptance tests while implementing new functionality. Has anyone ever done test-first with jack? One could start jackd in dummy mode with a random name, start some clients, wire inputs to outputs and compare the generated signal to the expected result, maybe with some fuzzy logic to allow for arbitrary delays. OTOH, if there are existing mocking libraries for jackd, things might be a bit more straight forward (provide an input buffer to be returned by jack_port_get_buffer, call the process function and check the result that's written to the output buffer). Any pointers will be highly appreciated. Cheers

13 years, 10 months

Python Gstreamer Live Video examples

by Nathanael Anderson

I'm just getting started with some python gstreamer coding, and Having trouble finding what I'd consider some basic examples: These I've already got working: 1. build a pipeline showing the attached video device like: gst-launch v4l2src device=/dev/video0 ! 'video/x-raw-yuv,format=(fourcc)YUY2,width=640,height=480,framerate=20/1' ! xvimagesink 2. Record and show video at the same time: gst-launch v4l2src device=/dev/video0 ! 'video/x-raw-yuv,width=640,height=480,framerate=20/1' ! tee name=t_vid ! queue ! xvimagesink sync=false t_vid. ! queue ! videorate ! 'video/x-raw-yuv,framerate=20/1' ! theoraenc ! queue ! oggmux ! filesink location=test.ogg I want to get working: 3. toggle recording, so I can show a video monitor, and without destroying and recreating the pipeline start or stop video recording at will. 4. Sync multiple pipelines, my end goal is to be able to record x video streams in sync, while playing back y videos with all play and record sources in sync (think video mixing). I'm looking for examples of 3 and 4, and improvement ideas to 1 and 2. Thanks, Nathanael

13 years, 10 months

Question about LV2 UI extension

by Paul Coccoli

I was looking at the (unfinished) example sampler plugin here: https://gitorious.org/gabrbedd/lv2-sampler-example I ran through the mental exercise of trying to figure out how to finish it, and I have a question about the UI extension. How does a UI tell its plugin to load a sample file? The example has a TODO in its run function that indicates it will react to an LV2_Event that contains a pathname for a file. I don't understand how a UI will create this event. On lv2plug.in, I see there's an experimental string-port extension that defines a transfer mechanism for strings. Is this the recommended method? Do any hosts support this extension? There's also an atom extension, but I don't think I grok it yet. Can I create a port of type atom:MessagePort? How does a UI make use of that?

13 years, 10 months

Fwd: Fwd: lv2 extension bugs

by Lieven Moors

On Mon, Jul 25, 2011 at 4:02 PM, David Robillard <d(a)drobilla.net> wrote: > On Mon, 2011-07-25 at 13:05 +0200, Lieven Moors wrote: > > OK, what happened was that I landed on the http://lv2plug.in/ns/ext > > page, was expecting a download extensions link, didn't find it, and > > downloaded > > the files manually from the links on those pages. > > The event extension page > > http://lv2plug.in/ns/ext/event > > does have a link to the latest release (1.2). > > -dr > > That is really odd. Did it change in the last couple of days? I'm sure I got the header from there, and I'm sure it had http in the address on line 28. Otherwise this is not a bug, it's a ghost... lievenmoors

13 years, 10 months

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Linux-audio-dev July 2011