Linux-audio-dev July 2007

linux-audio-dev@lists.linuxaudio.org

65 participants
39 discussions

How to get correct midi timings from ALSA using the library only

by Carlo Florendo

Hi, (1) I've written a command line MIDI sequencer for lightweight systems and am successful in making it work using the ALSA queue API. However, one drawback of the API is its lack of callback functions. I wish to be able to track events as they are drained by the queue. (2) I know and have successfully worked on a work around whereby the application itself subscribes to the output port so as to see events as they are played. However, I wish to be able to make the sequencer or player work without the use of the ALSA queue nor the workaround in (2). Here's the pseudo-code of the relevant MIDI player routine: for (i = 0; i < number_of_events; i++) { usleep(event[i].delta_time_in_microseconds); output_and_drain_event(event[i]); } This routine gives a non-bearable latency on 2.4 kernels but not so much on 2.6 kernels. How could I get the app to <u|nano>sleep() in the most accurate way in userspace without using the ALSA queue nor the extra subscription to an output port? Or, is there a drain or output routine that supports callbacks? If so, I will be grateful if you could point them out. I seem not to find any output callback routine under the docs. Thank you very much. Best Regards, Carlo -- Carlo Florendo Softare Engineer/Network Co-Administrator Astra Philippines Inc. UP-Ayala Technopark, Diliman 1101, Quezon City Philippines http://www.astra.ph -- The Astra Group of Companies 5-3-11 Sekido, Tama City Tokyo 206-0011, Japan http://www.astra.co.jp

16 years, 9 months

[ANN] lash_wrap - A small LASH wrapper

by Florian Schmidt

Hi, i planned to write this for quite a while and finally got to it [though it's not 100% working yet - It's a small program. If experienced unix hackers might look over y use of waitpit i'd be happy :)]: lash_wrap It's a small program which can be used to "smuggle" non LASH apps into a LASH session provided they meet some requirements: - If they are jack clients, there must be a way of determining the jack client name at startup time - If they are ALSA seq clients the client ID must be known at client startup time or their alsa seq name must be uniquely determined - They must require a way to specify their state via the commandline (e.g. we can tell ardour to load a certain ardour session at startup) So here's how i would smuggle ardour2 into a LASH session: lash_wrap -j ardour -- ardour2 ~/sound/ardour/brazil/brazil.ardour The -j [--jack-name] option tells lash_wrap it must register the jack name "ardour" with LASH. the "--" seperates the options for lash_wrap from the commandline to start the program in question. If we wanted also all ALSA SEQ connections of ardour to be restored we could do: lash_wrap -a ardour -j ardour -- ardour2 ~/sound/ardour/brazil/brazil.ardour The -a [--alsa-name] option specifies a name which will be used to find out the client ID of ardour by regularly searching all ALSA clients until one named "ardour" is found. This ID is then passed to LASH. CAUTION!!!! YOU MIGHT LOSE WORK!! READ ON: - lash_wrap does not care for saving the state of the app in question. So before hitting "close" in your favourite LASH session handler, be sure to save the session in e.g. ardour manually. - if the passed jack or alsa client names do not match for whatever reasons, then connections won't be restored properly. You have been warned. Nonetheless this might be useful for people who otherwise use scripts to manage their audio sessions. Download it here: http://tapas.affenbande.org/lash-wrap Regards, Flo P.S.: Apps like rosegarden are a bit difficult to handle, because they use wrapper scirpts themself that exit immediately and confuse my little app [into thinking the app exited, thus LASH thinks rosegarden has quit, too] -- Palimm Palimm! http://tapas.affenbande.org

16 years, 9 months

Re: [LAD] 2.4 vs 2.6

by arisstotle.52613058＠bloglines.com

--- joq(a)io.com wrote: On 7/20/07, Paul Davis <paul(a)linuxaudiosystems.com> wrote: > > On Fri, 2007-07-20 at 15:31 +0000, arisstotle.52613058(a)bloglines.com > > wrote: > > > I've been working with the 2.6 series kernel now for some time with satisfactory > > > results ie (about 24 msec of latency and solid stability). I chose the 2.6 > > > series because its the latest, and I wouldn't have to patch as much to get > > > support for my hardware (firewire alsa realtime etc...). But I've been reading > > > more and more about how the 2.4 kernels can outperform 2.6 when patched properly, > > > any truth to this? > > > > no truth. its an old data point, no longer valid. that is, assuming we > > are talking about RT-patched 2.6 vs. RT-patched 2.4. if you mean vanilla > > 2.6 vs. RT-patched 2.4, the latter is still better. > > I'm not sure that is even true any more. No recent data, but I tested jackd > extensively in about the 2.6.7 to 2.6.11 time-frame, and found those vanilla > 2.6 kernels quite competitive with RT-patched 2.4 ones, at least on the > machines I was running at the time (all uniprocessors). > > The very early 2.6.x kernels were another story. :-) > -- > joq > _______________________________________________ > Linux-audio-dev mailing list > Linux-audio-dev(a)lists.linuxaudio.org > http://lists.linuxaudio.org/mailman/listinfo.cgi/linux-audio-dev > when you all say RT Patched you mean realtime module built, loaded configured and used by jack correct?

16 years, 9 months

APIC, IRQ's, and realtime

by arisstotle.52613058＠bloglines.com

I've been trying to get a kernel built that will run smoothly, but this is the problem I keep running into, I compile the kernel with SMP processor support, because my processor is a dual core (duh right?) but as some may know, this automatically builds in APIC support. This then leads to unruly IRQ assignments, in my case, a quick cat /proc/interrupts will almost allways show my soundcard being shared with a usb port. of of course, to tease me even more, no assignment on irq 5, i've tried the whole hop-scotch game with the pci slots, nothing works. Help? -Thanks again

16 years, 9 months

FULL audio-signal path

by Andrew Gaydenko

Hi, All! Say, we have such audio-chain: 1. analogue source (say, mic-amp), 2. sound card's line input (let sound card be rme hdsp9632), 3. JackRack (or some other JACKified LADSPA host) with the only LADSPA plugin, let last one be a simple aplifier, 4.1. sound card SPDIF output. 4.2. sound card analogue output, OK, ALSA-driver, HdspMixer, JACK-server and something else are somewhere inside this "user' POV" list. The questions are: - what is full strict list of "audio-entities" steps in such roughly-presented chain? - which formats (float/integer, bitdepth) are used on each step? - which format convertions between steps may be treated as lossless and whcih as "lossness"? And more generally: are there common rules for keeping sound quality intact? I mean only format-related probable issues rather hardware issues like jitter and such. Andrew

16 years, 9 months

2.4 vs 2.6

by arisstotle.52613058＠bloglines.com

I've been working with the 2.6 series kernel now for some time with satisfactory results ie (about 24 msec of latency and solid stability). I chose the 2.6 series because its the latest, and I wouldn't have to patch as much to get support for my hardware (firewire alsa realtime etc...). But I've been reading more and more about how the 2.4 kernels can outperform 2.6 when patched properly, any truth to this?

16 years, 9 months

comments on (sparse) matrix libraries

by Georg Holzmann

Hallo list! I am searching for a sparse matrix library (prefered for C++, otherwise C) for an audio project. However, I found really many libraries and am a little bit confused which one I should take - so I wanted to ask here if someone can give me comments/suggestions to libraries they use ? Many thanks for any comment, LG Georg

16 years, 9 months

[ANN] QjackCtl 0.3.1a (unstable-qt4) crash-fix released!

by Rui Nuno Capela

Hi again, QjackCtl 0.3.1a (unstable-qt4) crash-fix released! This is an emergency crash-fix release and everyone is envited to ditch yesterdays one. The change-log just says it all: - An immediate showstopper crash upon client start was irradicated, which was affecting those with the system-tray icon disabled, as is the default (thanks to Ken Ellinwood for first reporting this sloppy one). Again, the fix source tarball is made available from: http://qjackctl.sourceforge.net http://sourceforge.net/projects/qjackctl Cheers && Enjoy, -- rncbc aka Rui Nuno Capela rncbc(a)rncbc.org

16 years, 9 months

audio conversion functions

by Craig Hoedebeck

I am relatively new to audio programming, but I have a task that requires converting between various audio formats: unsigned 16 bit linear to signed 16 bit linear u_law to signed 16 bit linear a_law to signed 16 bit linear unsigned 8 bit linear to signed 16 bit signed 8 bit linear to signed 16 bit Anyone know what the conversion functions for these would look like? Or even what a good reference is where I can find these? I have been googling around for about an hour and I have come up empty. ____________________________________________________________________________________ Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out. http://answers.yahoo.com/dir/?link=list&sid=396545469

16 years, 9 months

[ANN] QjackCtl 0.3.1 (unstable-qt4) is out!

by Rui Nuno Capela

Greetings y'all, Just one week after a no-regrets migration, here comes this second iteration over the Qt4 framework for the JACK Audio Connection Kit "cutie" GUI front-end that everybody loves or at least ought to :) QjackCtl 0.3.1 (unstable-qt4) is out! The main feature on this release, besides for the bug-fixes, is that it's the very first time ever QjackCtl is made available to build and run on all major desktop platforms: X11/Linux, Windows and Mac OS X. Yes you read it right, Windows, and it is thought to behave consistently on all those. One just have to take advantage from the Qt4 open-source edition and license which in fact is the same as QjackCtl's: GPL2. Yes, there's no turning back. QjackCtl is definitely a Qt4 application, this release marking the departure from the old, aged Qt3 code base, despite this one being tagged as "stable-qt3" anyway. The current branch has "unstable-qt4" on its middle name still, but not for long ;) Being a so-called shallowed bug-fix release, the change-log says some thingies that were shoved out, and nothing about the ones that still are creepin': - The current DSP load percentage activity is now also displayed on the system-tray icon tooltip. - An illusive but nasty Connections/Patchbay item tooltip crash bug has been hopefully fixed (Qt >= 4.3). - Now using QSystemTrayIcon class facility if available (Qt4 >= 4.2) making the system-tray option available on most platforms, notably on Windows and Mac OS X (EXPERIMENTAL). - Usage of QProcess class has been severely refactored, now using QProcess::start() instead of QProcess::startDetached(), giving much tighter control over the started jackd(mp) process. Downside is that QjackCtl lost its ability and option to leave the process detached upon quitting the application. Too bad. - A new eye-candy bit has sneaked in: server mode display, that is the RT indicator, now blinks when server/client is started/active. - Combo-box setup history has been corrected on restore, which was discarding the very initial default (factory) contents. - Now that Qt4 is accessible to open-source Windows appplications, there's some experimental stuff sneaking in for jackdmp support on win32 (http://www.grame.fr/~letz/jackdmp.html). - Connections list items were initially sorted in descending order by default. Fixed. Client items are now naturally sorted, again. As usual, the source tarball might be found here: http://qjackctl.sourceforge.net http://sourceforge.net/projects/qjackctl Cheers && Enjoy, -- rncbc aka Rui Nuno Capela rncbc(a)rncbc.org

16 years, 9 months

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Linux-audio-dev July 2007