Linux-audio-dev

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7516 discussions

by Lars Luthman

This software package contains libraries and programs that should make it easier to write LV2 plugins and GUIs. Download it: http://ll-plugins.nongnu.org/hacking.html Read documentation: http://ll-plugins.nongnu.org/dox/lv2-c++-tools/ Or read a nice tutorial: http://ll-plugins.nongnu.org/lv2pftci/ To build and install, run ./configure make su -c 'make install' You can pass some options to configure, e.g. --prefix=/usr to install everything in /usr (the default is /usr/local). This is a development tool, but I'm sending it to the LAU list as well in case there are any not-yet-hackers who would like to start writing effects or synths. It's easy, I promise. Here's the code you would need to write for a simple gain effect: #include <lv2plugin.hpp> #include "gain.peg" class Gain : public LV2::Plugin<Gain> { public: Gain(double rate) : LV2::Plugin<Gain>(p_n_ports) { } void run(uint32_t nframes) { for (uint32_t i = 0; i < nframes; ++i) p(p_out)[i] = p(p_gain) * p(p_in); } }; static int _ = Gain::register_class("http://my.plugin/"); And here's the code you would need for a GUI for a synth plugin with a button that sends a test tone: #include <lv2gui.hpp> #include "mysynth.peg" class MySynthGUI : public LV2::GUI<MySynthGUI, LV2::WriteMIDI<true> > { public: MySynthGUI(const std::string& URI) : m_button("Click me!") { m_button.signal_pressed().connect(mem_fun(*this, &MySynthGUI::send_note_on)); m_button.signal_released().connect(mem_fun(*this, &MySynthGUI::send_note_off)); pack_start(m_button); } protected: void send_note_on() { uint8_t event[] = { 0x90, 0x40, 0x40 }; write_midi(p_midi, 3, event); } void send_note_off() { uint8_t event[] = { 0x80, 0x40, 0x40 }; write_midi(p_midi, 3, event); } Gtk::Button m_button; }; static int _ = MySynthGUI::register_class("http://my.gui/"); See? Trivial. Read more in the tutorial linked above. --ll

17 years, 6 months

Some LV2 news

by Lars Luthman

...for those who do not follow the LV2 mailing list. 1. EVENTS There is an extension for sending arbitrary events to and from plugin ports here: http://lv2plug.in/ns/ext/event#EventPort This extension specifies how to send MIDI events using those ports: http://lv2plug.in/ns/ext/midi#MidiEvent MIDI event support is implemented in Elven, Ingen, lv2_jack_host (and more?) and a couple of experimental plugins (a virtual keyboard, a basic drum machine, some MIDI utilities, some synths). There is no published OSC event type spec yet, but there are experimental hosts that are sending OSC to and from plugins and GUIs using the event ports. 2. UIS Here is an extension that defines a framework for embedded LV2 (G)UIs: http://lv2plug.in/ns/extensions/ui So far there is only a Gtk+ 2.0 GUI type specified, but others would be easy to add if someone writes up a spec for them. This is supported by Elven, Ingen (and more?) and a couple of plugins (e.g. above mentioned virtual keyboard and synths). There are also a bunch of other extensions for port grouping, saving and restoring the internal state of a plugin, and other stuff. See http://lv2plug.in for more information.

17 years, 6 months

cortado (gstreamer) [ot-ish]

by Julien Claassen

Hi Everyone! Sorry, it's not exactly audio itself: But has anyone of you experience with the cortado-java-applet? It's the multimedia-player applet, that's written by the gstreamer guys. The questions I have: 1. Can anyone recommend a certain version of it? - The version I have requires a VERY NEW java. 2. Does anyone know if there are constraints on the size of it? - I planed to put it in the upper left corner of a site. It's supposed to be roughly 20% by 20% of the browser-window. Is that too small? Sorry for asking this, but as a lot of you know, I'm blind and I can't really control, what I'm doing here. Kindest regards and any help is appreciated! Julien -------- Music was my first love and it will be my last (John Miles) ======== FIND MY WEB-PROJECT AT: ======== http://ltsb.sourceforge.net the Linux TextBased Studio guide ======= AND MY PERSONAL PAGES AT: ======= http://www.juliencoder.de

17 years, 6 months

Updates

by Fons Adriaensen

Hello all, Some updates on <http://www.kokkinizita.net/linuxaudio/downloads>: jmeters-0.2.0 - VU-meter scale replaced by a new one which does not have the -20dB threshold. Now it will also move for low-level sounds, and fall back much more naturally. - PPM now has the same size as VU. Old one still available as ppm2. - Added options to set jack client name and update rate. - Bugfix for Makefile, PNGs now get installed in $(PREFIX)/share instead of /usr/share. aeolus-0.8.1 - Aeolus-0.8.0 added Midi over Jack support but was announced on the Aeolus list only IIRC. With 0.8.1 it's official. - Major cleanup and bugfixes. - Replaces 0.6.6. as the supported release. ambdec-0.2.0 - Bugfixes, new collection of config files. MCP-plugins-0.4.0 - Major cleanup (after 5 years or so). - Added triple chorus. Same as chorus2 but has three outputs. Pan L,C,R for a nice stereo effect. clthreads-2.4.0 - Cleanup. clxclient-3.6.1 - Cleanup. - Probably fixes a bug that occurs only when running in KDE (windows not repainting when exposed). Many thanks to all who contributed by providing feedback, bug reports and patches. The two libs and ambdec now also have an OSX Makefile and the necessary #ifdefs to make them compile. This is very experimental. I will provide *no* support for this except to OSX developers who can provide the required technical feedback. Ciao, -- FA Laboratorio di Acustica ed Elettroacustica Parma, Italia Lascia la spina, cogli la rosa.

17 years, 6 months

LADSPA plugin behavior and naming, and more general questions

by Justin Smith

As a learning exercise, I made a LADSPA plugin that adds its inputs. I figured it would be reasonable to call such a thing '+'. Some plugin hosts don't like that (I was less surprised by the ones that could not handle the name '<'). This is the LADSPA_Descriptor.Label property. ladspa.h says "Labels must not contain white-space characters.". Is it unreasonable to expect to be able to have symbols as plugin labels, or parts of plugin labels? So this is more of a "what do you think" then a right/wrong answer kind of thing. Also, though ladspa.h does not say I cannot write my plugin library in such a way as to create resources shared by all the instances of my plugins within one host (say, a shared OSC connection?), would that be acceptable? Would that break hosts? What about per plugin GUI? If I just made a Makefile variable for a GUI to launch for a ladspa plugin, if I did not want the overhead of the full DSSI interface (or if I wanted to use the plugin in a non DSSI compatible host), would that be beyond the pale for a LADSPA plugin? Also, now that GMPI seems all but officially dead, does anyone think DSSI will be supplanted (or "disposed of", as its name would imply)? What is the general developer feeling regarding LADSPA/DSSI/LV2? I leave VST out of this list, because I don't think Linux distros can even legally distribute vst.h.

17 years, 6 months

Calibrating sound cards

by James Courtier-Dutton

Hi, Is there a recognized method for calibrating a sound card? e.g. For Playback, one sends a sample .wav PCM file to the sound card, then measure the analog output from the line-out. If the sound card itself provides 0dB of Gain, what should be the measured figure? Can this be done with a simple AC volt meter? There seems to be some debate, with regards to ALSA, as to whether the line-out is at the correct level if one sets all the ALSA mixer controls to 0dB. James

17 years, 6 months

audio meters nostalgia

by Fons Adriaensen

The first (beta) release of Jmeters is available at <http://www.kokkinizita.net/linuxaudio/downloads> Jmeters is a Jack multichannel audio level meter app. It looks very similar to meterbridge since it uses the same pixmaps. This first release offers VU, PPM and stereo versions of the same. The stereo versions have two indicator needles on the same scale. I've never seen a twin VU, but stereo (or M/S) PPMs *do* exist. Later releases will add bargraph meters, digital peak indicators for the analog ones, and a stereo correlation meter. The main difference to meterbridge is that Jmeters has the correct ballistics for both the VU and the PPM. The VU meter measures the average of the absolute value of the signal, 'average' meaning a second order filter that reaches 99% in 300ms and overshoots between 1.0 and 1.5%. It is calibrated to indicate 0dB for a sine wave at -10dB w.r.t. digital full scale (which is +/-1 peak in this case). The particular VU scale used is not entirely linear and starts at -20dB (it's one designed for a passive VU meter with a diode bridge), so the meter will not move at all for inputs below that level. Later versions may use a VU scale designed for an active meter which doesn't have this threshold. The PPM is a pseudo-peak meter. It will indicate 80% of the steady-state value for a 10ms burst, and fall by 24db in 2.8s. Each scale division (1..7) represents 4dB. It is calibrated to indicate '7' (+12 dB on the EBU scale) for 0dB FS. For speech and music with distinct short peaks the PPM will usually indicate higher. For music with continuous long notes, and for heavily compressed signals the VU indicates higher. Both meters require some 'getting used to' in order to read them correctly. You can modify the calibration by using the -g(ain) option, but it should normally not be necessary. Enjoy ! -- FA Laboratorio di Acustica ed Elettroacustica Parma, Italia Lascia la spina, cogli la rosa.

17 years, 6 months

FreeBoB 1.0.11 released (package fix)

by Pieter Palmers

The 1.0.10 package released a few weeks ago seems to have some packaging issues (missing files etc...). Therefore a new package has been uploaded that should fix these issues. Available at sourceforge: https://sourceforge.net/project/showfiles.php?group_id=117802 Greets, Pieter

17 years, 6 months

Re: [LAD] [ANN] jack_capture V0.9.10 and Snd-ls V0.9.8.16

by Jonathan Woithe

> jack_capture > : > *Added the --meterbridge / -mb option, which automatically > starts Steve Harris' meterbridge (http://plugin.org.uk/meterbridge/) > and constantly connects them to the same ports as jack_capture > is connected to. Nice - this will save me the hassle of starting meterbridge manually when setting up for recording and having to make sure that meterbridge's channels actually match jack_capture's channels. Thanks for the update! jonathan

17 years, 7 months

Re: [LAD] [LAU] new! linuxmusicians.com

by Ivica Ico Bukvic

> I'm just playing devil's advocate here, but the Linux audio community > hasn't exactly been lacking in this area: > > http://www.linuxaudio.org/ > > Is a portal to all kinds of things related to Linux audio (including > this mailing list). > > Not to mention the http://linux-sound.org/ site also. Let me take this one step further and state that the entire linux-sound.org database has been ported over into apps.linuxaudio.org with full user access to maintaining/altering the content which makes linux-sound maintenance unnecessary (esp. since Dave has effectively decided not to keep it up to date as often as he would like to). I think it would be nice if we all put efforts towards a common goal, especially since linuxaudio.org is all about the community. If there is an aspect of the lao domain you don't like, you are more than welcome to contribute... That being said, as always, we continue to be in dire need of assistance/support in making linuxaudio.org better. This is why I perceive the fragmentation of community resources to be moving us farther away from the place where we ought to be and where the consolidated online presence would be truly useful and meaningful to a community as small as ours. Best wishes, Ivica Ico Bukvic, D.M.A. Director, Linuxaudio.org Virginia Tech Dept. of Music - 0240 Blacksburg, VA 24061 (540) 231-6139 (540) 231-5034 (fax) ico(a)linuxaudio.org www.linuxadio.org

17 years, 7 months

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Linux-audio-dev