Linux-audio-dev September 2011

linux-audio-dev@lists.linuxaudio.org

28 participants
23 discussions

[LAD] Inter thread Communication: Design Approach

by Harry van Haaren

Hey All, I'm looking to improve a program's design with regards to how it communicates between the "jack" thread and its "main/gui" thread. Please note I'm *not* looking for implementation details like what ringbuffer to use, this has been discussed here before. Conditions: Gui needs to feed data trough to the jack thread (data = parameter moves etc) Jack thread needs to push data (buffers for waveforms & "playhead" info) The real question: What is a neat solution to passing various data trough a ringbuffer? My (hacky?) solution: Create a class, call it "Event". Runtime now looks like so: 1. Create a EventType enum, set the details 2. Write those "Events" into the ringbuffer 3. Switch based on EventType, and handle the event. While not terribly ugly, that Event class starts to get bigger & nastier, so I concidered sub-classing it... but I'm not sure this is going in the right direction. I'm very intrested how the "big" programs around have approached this problem... Cheers, -Harry

14 years, 5 months

[LAD] IR: Lv2 reverb (without the GUI..?)

by Harry van Haaren

Hey All, I'm faced with a problem that I can't see an easy way around regarding the use of the IR reverb plugin. I'm running the GUI in a seperate *process*, and doing all lv2 communication over OSC. For the most part this is easy, the problem rears its head when one want's to use a plugin whose UI requires "instance-access". Basically, the IR plugin GUI needs access to the Lv2_Handle. But I can't provide that due to the OSC communication. So I've concidered "spoofing" a plugin on the UI side, and keeping it up to date with what the "real" one is doing in the Engine. Bit ugly, and if the UI has instance access, will it still call the normal "port" events..? Because otherwise I'm lost with trying to get at the UI data. The other problem is that loading a "sample" into the IR convolution happens in a pretty strange way: there's 3 Control Input ports, and together they make up a 64bit file hash. I understand the reasons behind this decision, and I'm not trying to criticise the implementation, I'm just not sure how I can send a certain file to these ports to make it work... -Harry

14 years, 5 months

Re: [LAD] Inter thread Communication: Design Approach

by Florian Paul Schmidt

On 09/02/2011 12:54 PM, Pedro Alves wrote: > boost::function<void(void)> serves this purpose for me in jass. To >> create and pass a functor that assigns a new auditor generator to the >> one in the engine, and then tells it to play i do for example: >> >> write_blocking_command(assign(engine_.auditor_gen, p)); >> write_blocking_command(boost::bind(&engine::play_auditor, >> boost::ref(engine_))); assign() is just a utility template to make >> creating functors that do assignments easier.. boost::bind is used to >> make all passed functors 0-ary (e.g for binding member functions to >> their instance or binding arguments to the functor.. and >> write_blocking_command is just a utility function that disables the GUI >> until the acknowledgement from the engine has come back to the GUI,, The >> command ringbuffer is just a ringbuffer holding >> boost::fucntion<void(void)> objects.. >> >> typedef ringbuffer<boost::function<void(void)> > command_ringbuffer; >> >> Examples from here: >> https://github.com/fps/jass/blob/master/main_window.h >> https://github.com/fps/jass/blob/master/assign.h >> https://github.com/fps/jass/blob/master/engine.h Regards, Flo > There are alternatives (even predecessors) to boost.function that > are much faster and avoid the heap/new. See > <http://www.codeproject.com/KB/cpp/fastdelegate2.aspx> for example. > (I used Don's original "Fastest Possible C++ Delegates" on an embedded > project years ago -- worked great). > Oh, thanks for the interesting read :D Flo

14 years, 5 months

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Linux-audio-dev September 2011