Linux-audio-dev January 2006

linux-audio-dev@lists.linuxaudio.org

83 participants
66 discussions

[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, 8 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, 8 months

[linux-audio-dev] [ANN] sverb 0.9

by Cedric Roux

Hello Linux Audio People, sverb is a CFDN order 15 reverb. It is available at: http://sed.free.fr/sverb 0.9 is the first public release. Any help/hacking/whatever is very welcome. Take care, Cédric.

18 years, 8 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, 8 months

[linux-audio-dev] [admin] music.columbia.edu server downtime

by Joern Nettingsmeier

hi everyone! a happy new year to all folks on the gregorian calendar, and a generic happy next 365 days to everyone else! the music department at columbia university are taking the list server down for an upgrade on the coming weekend, so expect interruptions for linux-audio-dev, linux-audio-user and linux-audio-announce. you will probably want to keep a copy of all the mails you send over the weekend, so that you can re-send them in case they end up in the bit bucket. let me take this opportunity to thank douglas irving repetto for many years of painless hosting and friendly help, and the entire music dept. for their generous donation of iron and bandwidth. kudos, guys! rumor has it that the new list server will be an os x machine. hopefully this will make the lists even more user-friendly and aesthetically pleasing than before ;) all the best, jörn -------- Original Message -------- Subject: music.columbia.edu server downtime Date: Mon, 2 Jan 2006 16:21:13 -0500 From: douglas irving repetto <douglas(a)music.columbia.edu> To: douglas(a)music.columbia.edu Hello, We will be upgrading the music.columbia.edu server this weekend. Hopefully all of the work will be done on Saturday, but it may extend into Sunday. music.columbia.edu will not be available during the downtime. That means no websites will be served, no email will be sent/delivered, no mailing lists will function, etc. I'll send an update later this week with info about some changes that you'll see on the new server. Happy new year, douglas -- ............................................... http://artbots.org .....douglas.....irving........................ http://dorkbot.org ................................ http://ceait.calarts.edu/musicdsp .......... repetto....... http://works.music.columbia.edu/organism ............................... http://music.columbia.edu/~douglas -- jörn nettingsmeier home://germany/45128 essen/lortzingstr. 11/ http://spunk.dnsalias.org phone://+49/201/491621 if you are a free (as in "free speech") software developer and you happen to be travelling near my home, drop me a line and come round for a free (as in "free beer") beer. :-D

18 years, 8 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, 8 months

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Linux-audio-dev January 2006