Linux-audio-dev December 2005

linux-audio-dev@lists.linuxaudio.org

61 participants
53 discussions

Re: [linux-audio-dev] 3D fft analysis program

by Downer

> I'm hoping that you're thinking of a realtime display, in which the > peaks roll off to create a true waterfall effect. Baudline (http://www.baudline.com) is a fantastic viewer that does fft cascade. I've used it for a couple of years, and it is great for figuring out how different sounds "work", and it has an oscilloscope-type display as well. Cheers, Jason Downer

18 years, 6 months

[linux-audio-dev] Drum synth

by Dmitry Baikov

Hello. I finally started making my pet music project and realized I need a drum synth to make some cool sounds. psindustrializer is good but also need some tr-909-style sounds. I remeber from my old windoze days I used a nice piece of software called Stomper. Does anybody know any software for linux with comparable capabilities? Or we need to write one? Stomper does not work under wine :( Thanks.

18 years, 6 months

[linux-audio-dev] Re: Drum synth

by Juhana Sadeharju

Hello. I had a couple of articles on drum synths. Check ftp://ftp.funet.fi/pub/sci/audio/devel/lad/drumsynth/ I built the circuit in a00*.jpg at the time when this article was fresh. The article b00*jpg mentions an earlier article. I will check that out at library. Hmm.. I coded a drum synth for Commodore VIC-20 at the time. VIC provided an audio chip with three oscillators, noise, and a common volume if I remember correctly. What I did was to modulate osc pitch and volume parameters with a fast and accurate (compared to Basic) assembly code. The drum sounds were assigned to the keys. This was about 1984, inspired by Yamaha's digital RX drum synths, not by analog drums. Juhana -- http://music.columbia.edu/mailman/listinfo/linux-graphics-dev for developers of open source graphics software

18 years, 6 months

[linux-audio-dev] python and jack, performance report

by Leonard "paniq" Ritter

-- oops, the first one was sent as a reply, here's the whole thing as a new thread. frustrated by the poor implementation of the jack bindings for python (pyjack), i wrote my own in native python using ctypes. the first test client mixed a 440hz sine wave using native python lists, and the cpu usage was about ~11%. i reimplemented the sine generator with numerics, and got it down to ~2%. i believe that considering the overhead of the python implementation, that result isn't too bad, and maybe allows for more than just prototyping. i attached the jack wrapper with the test client contained for those who are interested. its not entirely wrapped and lacks some functionality. -- -- leonard "paniq" ritter -- http://www.mjoo.org -- http://www.paniq.org

18 years, 7 months

[linux-audio-dev] Re: lad design patterns

by Juhana Sadeharju

>From: "Levi D. Burton" <ldb(a)puresimplicity.net> > >does the idea of documenting various lad design patterns make >sense to anyone? Such "LAD Gems" doc would be much needed here too. (For audio dsp gems, take a look at "musicdsp.org".) I would appreciate if somebody would take a look at Ardour and document best gems found there. E.g., the GUI and audio thread separation and start up sequences. Likewise for Linuxsampler and one of its GUI frontends. Juhana -- http://music.columbia.edu/mailman/listinfo/linux-graphics-dev for developers of open source graphics software

18 years, 9 months

[linux-audio-dev] [ANN] jack_capture v0.0.1

by Kjetil S. Matheussen

http://www.notam02.no/arkiv/src/ ABOUT ----- jack_capture is a small simple program to capture whatever sound is going out to your speakers into a file. This is the program I always wanted to have for jack, but no one made. So here it is. USAGE ----- jack_capture [-f filename] [ -b bitdepth ] [-c channels] [ -B bufsize ] Filename is by default auotogenerated to something like "jack_capture_<date+exact_time>.wav" Bitdepth is by default FLOAT. Channels is by default 2. Bufsize is by default 262144. ACKNOWLEDGMENT -------------- Mostly based on the jackrec program in the jack distribution made by Paul Davies and Jack O'Quin. Automatic filename generation code taken from the timemachine program by Steve Harries. --

18 years, 9 months

[linux-audio-dev] Olypus voice recorder - codec?

by Dan Stromberg

Hi folks. This message does get into driver specifics to an extent, but I'm mostly coming to list for advice on how to find what "mystery codec" is being used. I've been putting some of the tiny bit of actual freetime I get during this winter holiday :), into trying to get a libusb-based driver going for my little Olympus VN480PC. It's a digital voice recorder that comes with a USB cable for transferring voice recordings to a computer, and the accompanying software is windows only. I'd very much like to be able to do this transfer using linux instead of needing windows though. I think I -might- have the protocol mostly figured using a USB sniffer on the windows side, but that may prove to be the easy part of this project. :-S What I'm faced with now, is I have 10K of data which I'm assuming just about has to be the voice data in some format or other - but it isn't clear what format it's in. Toward trying to figure out the format, I've: 1) Computed the difference in the lengths of the apparently-voice data transferred via USB, and the "data" section of the resulting .wav file. They do not differ by a constant - so it's not just a matter of tacking on a header. 2) Computed the quotient of the lengths of the apparently-voice data transferred via USB, and the "data" section of the resulting .wav file. They do not differ by a constant factor - so it's not just a matter of converting, for example, shorts to reals again and again, for example, in which case the lengths, I would think, should differ by a constant factor of 2. 3) Symlinked a file containing the data transferred via USB, to all of the file extensions known to sox, and attempted to use sox to convert those files to .wav. None of the conversions succeeded. 4) Wrote a small python program to treat the data transferred via USB as data to be stuffed into the "data" section of a .wav file, and created a series of .wav files with all format types from 0 to 999. sndfile-info did not give errors for 9 of these, but none of them look or sound right in gnusound. 5) Googled about olympus and voice/audio codecs, to see if there is a proprietary one they favor. It appears they were involved in the design of the "DSS" format. 6) Downloaded "DSS Player Lite" from Olympus' web site, and copied the data transferred via USB to "hi.dss". However, DSS Player Lite did not recognize the file format. Does anyone have any thoughts about what else I might try to see what format this data is in, and/or convert it to a known format? I've got detailed documentation of most of what I've done so far on this project at http://dcs.nac.uci.edu/~strombrg/VN480PC/ The page includes some .wav's, a binary file I'm assuming is voice data in a mystery codec, full USB sniffer logs, and so on. Does anyone have any suggestions - especially toward how to convert that "likely voice data" in the USB Sniff to some sort of known and supported-on-linux codec? Thanks!

18 years, 10 months

[linux-audio-dev] OT: Wikipedia, FM and John Chowning

by Jens M Andreasen

Hi! Seems like the father of FM-synthesis has joined wikipedia. Some of you guys might care to take a brief look at the FM-synthesis page, just once in a while, so it wont get vandalised again? -- mvh // Jens M Andreasen

18 years, 10 months

Re: [linux-audio-dev] Audio/Midi system - RT prios..

by Chris Cannam

Florian Schmidt writes: > I further assume that the alsa seq event system > is used This is true of Rosegarden, > and midi events are not queued > for future delivery but always delivered immediately. but this isn't -- Rosegarden always queues events from a non-RT thread and lets the ALSA sequencer kernel layer deliver them. (Thru events are delivered directly, with potential additional latency because of the lower priority used for the MIDI thread.) In principle this should mean that only the priority of the receiving synth's MIDI thread is significant for the timing of sequenced events. We also have a mechanism to compensate for gradual drift between the MIDI timing source (kernel timers or RTC) and soundcard clock, when synchronising to audio, by adjusting the sequencer skew factor. (This happens to be similar to the mechanism for slaving to MTC, which is handy.) In my experience this is all a long way from foolproof. The most common problems for users seem to be: - ALSA sequencer uses kernel timers by default and of course they only run at 100 or 250Hz in many kernels. - ALSA sequencer can sync to RTC, but the associated module (snd-rtctimer) appears to hang some kernels solid when loaded or used. I don't have much information about that, but I can probably find out some more. - ALSA sequencer can sync to a soundcard clock, but this induces jitter when used with JACK and has caused confusion for users who find themselves inadvertently sync'd to an unused soundcard (the classic "first note plays, then nothing" symptom). The biggest advantage of course is not having to run an RT MIDI timing thread. My impression is that this aspect of MusE (which does that, I think) causes as many configuration problems for its users as using ALSA sequencer queue timers does for Rosegarden's. Any more thoughts on this? Chris

18 years, 10 months

Re: [linux-audio-dev] Audio/Midi system - RT prios..

by Pedro Lopez-Cabanillas

On Friday 30 December 2005 17:37, Werner Schweer wrote: > The ALSA seq api is from ancient time were no realtime threads were > available in linux. Only a kernel driver could provide usable > midi timing. But with the introduction of RT threads the > ALSA seq api is obsolete IMHO. I don't agree with this statement. IMHO, a design based on raw MIDI ports used like simple Unix file descriptors, and every user application implementing its own event schedule mechanism is the ancient and traditional way, and it should be considered obsolete now in Linux since we have the advanced queueing capabilities provided by the ALSA sequencer. You guys are talking here about MIDI timing, considering only the event scheduling point of view, as if Rosegarden or MusE were simple MIDI players. Of course, playing beats on time is a required feature. But my bigger concern about MIDI timing issues is when you are *recording* events. Here is where ALSA queues, providing accurate timestamps for incoming events, are so good. It could be the absolute winner if problems like the audio synchronization and slave MTC synchronization were solved likewise. Regards, Pedro

18 years, 10 months

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Linux-audio-dev December 2005