Linux-audio-dev

linux-audio-dev@lists.linuxaudio.org

3 participants
7535 discussions

by Patrick Shirkey

Hi, I'm working on a cross platform mobile OS media player and doing some research into Realtime audio playback on Android at the moment. It seems there is a fairly small amount of info online and a lot less fully fledged code examples than available for the iPhone platform. For example I have already implemented my demo app in objective-C but it looks like it is going to be significantly more effort to do the same for Android. I have found a couple of interesting posts and articles about the current state things. Maybe people round here would like to comment on the situation? Here's what I have found so far: 1: There are three main API's - mediaPlayer, SoundPool, AutdioTrack with openSL ES in the works for release sometime in the near future. 2: All of the Android API's do not provide true low latency support and have varying bugs that need to be worked around with native code. The pd team have made some progress on the workarounds based on jack style callback wrapper classes. 3: There is no standard library for decoding audio file formats at the lower level. Although several options exist including native java implementations for mp3 (JLayer), and custom code from developers like Ivan Memruk from mindtherobot.com 4: There is no native midi or OSC support and it looks like there is no LV2 or ladspa port at this point either. There are very few open source demo apps available which provide a complete solution for media playback and recording at low latency. It seems that the pd implementation is the only one. Overview: http://www.wiseandroid.com/post/2010/07/13/Intro-to-the-three-Android-Audio… http://mindtherobot.com/blog/555/android-audio-problems-hidden-limitations-… <http://mindtherobot.com/blog/555/android-audio-problems-hidden-limitations-…>pensl-es/ <http://mindtherobot.com/blog/555/android-audio-problems-hidden-limitations-…> Sample code: http://mobiledeviceprogramming.blogspot.com/2010/10/fun-with-android-audiot… http://mindtherobot.com/blog/580/android-audio-play-a-wav-file-on-an-audiot… http://mindtherobot.com/blog/624/android-audio-play-an-mp3-file-on-an-audio… http://blog.pocketjourney.com/2008/04/04/tutorial-custom-media-streaming-fo… Workarounds / Middleware: http://gitorious.org/pdlib http://www.typhon4android.org/ Cheers. -- Patrick Shirkey Boost Hardware Ltd.

14 years, 9 months

Re: [LAD] [ann] CAPS 0.4.5

by Jeff McClintock

> An informal experiment shows that jack-rack 1.4.7 and ardour 2.8.11 > both do exactly the right thing when a plugin referenced by a saved > session gains a port: they set the new port to its default value and > happily carry on working. > > (Both also cope with the removal of a port. These are the only > publicly available hosts I have tested.) What happens when you modify version-1 of your plugin and remove a port (making Version2), then later re-add a new (unrelated) port with different semantics? (Version 3)... Then load a project created with version 1. Does the host in THIS situation set the new port to it's default value, I doubt it. More likely it 'restores' it to some invalid setting. Do you want a fragile, crash-prone, plugin ecosystem?, or a robust one? I Agree with Paul on this one. Best Regards, Jeff

14 years, 9 months

[LAD] Denemo version 0.9.0 has been released.

by Nils

Denemo version 0.9.0 has been released. Denemo is a program for inputting music notation. http://www.denemo.org The music being entered is displayed as conventional music notation and can be typeset via GNU LilyPond and played via internal synthesizer. Scheme scripting allows the user to generate music tests, music training exercises and some educational games are included. This is a major release filling out many features, fixing lots of minor irritations in earlier versions and providing powerful features unavailable from any other notation editor. * New features in this version: * Undo and Redo * Undoes all work on any movement with depth limited only by (virtual) memory size. * Re-do any number of Undo steps. * Chord Entry from MIDI keyboard * Auto advance of cursor * With status on MIDI-in status bar * Auto-notate chordal accompaniment * Conductor * Drive the playback with the mouse, pause, speed up, slow down just by moving the mouse * Works with looping/editing enabling you to listen in detail as you step through a passage * Play Along * Choose one part to play via MIDI in, Denemo plays the rest waiting for you if you pause * Works with recording, so you can add improvisations * MIDI shortcuts * Delete Selection without removing empty measures * Standalone Fermata: On barlines, other objects, between notes etc. * Small / Half sized Barline * Phrasing Slurs * Five Presets for different Voices (1-4 and Automatic), resembling Lilyponds \voiceOne \voiceTwo etc. * Separate Export command for saving LilyPond, MIDI * save a copy of the score while continuing to work on the original. * Accompanist's Score * Scrolling and zooming for the Print Preview window * Lilypond Importer: * Fermata * Partial / Upbeat / Anacrusis * Tied notes * Custom beaming (Lilypond brackets [ ]) * Staff/Instrument names and short instrument names * Staff Groups * Staff Groups now each have their own command * Added GrandStaff grouping * Help Frame to show key bindings and other info directly in Denemo * New set of (real, physical) transpose/shift commands * Arbitrary transposition - specify two notes or the name of the interval * Tonal step up / down (stay in key) * Real whole tone up / down (tranposition) * Real half tone up / down (tranposition) * Real octave up / down (tranposition) * Join Music Objects: Create a new note from a selection of others * Join Music Objects 2: Create a new chord with all pitches and the sum of a selection * Support for all notehead-styles Lilypond offers (default, cross, mensural, diamond, slashs and more) * Create chords with interval-based commands and shortcuts (major 7th, minor 3rd, perfect 5 and so on) * NotationMagick * Reverse selected notes * Mirror selected notes on any axis, e.g. middle-staff-line * Sort selected notes according to pitch, ascending and descending * Shuffle selected notes. * Generate rhythms from strings, converted to ascii binary numbers used as rhythm. * Lyrics * Fix overlapping display * Allow scripted insertion of lyrics * Paste arbitrary lyrics including accents, multiple words to one note, multiple notes to a syllable. * Paste * rewritten: more robust and faster * deactivated playback of pasted content * new variant to replace the selection * Figured Bass * Improve display, can now be used to play off screen * Educational * Handel's Figured Bass exercises: Play in, then Denemo analyzes your realization for consecutive 5ths and octaves. Known Issues for this version: * Playback does not get priority over other tasks. This will be addressed in the course of gsoc 2011. * Not all LilyPond features are directly available via the GUI. Here are the compressed sources (from a mirror) : http://ftpmirror.gnu.org/denemo/denemo-0.9.0.tar.gz If automatic redirection fails, the list of mirrors is at: http://www.gnu.org/order/ftp.html Or if need be you can use the main GNU ftp server: http://ftp.gnu.org/gnu/denemo/denemo-0.9.0.tar.gz

14 years, 9 months

[LAD] LWN feature: Gleixner on the inclusion of the PREEMPT_RT patches into mainline

by Jörn Nettingsmeier

hi! guess this will be of interest to LAD patrons: http://lwn.net/SubscriberLink/440064/dff63f71e1002605/ best, jörn

14 years, 9 months

[LAD] LV2 mailing list

by David Robillard

Hi all, Unfortunately we've had a bit of a hosting transition hiccup at lv2plug.in and the mailing list has been lost. There is a new list at the same location, but you will have to subscribe again. Sorry for the inconvenience. In related news. http://lv2plug.in is now a Trac installation, feel free to sign up and use the Wiki and ticket system for anything LV2 related. The timeline gives a nice overview of development happening in the SVN repository as well, which should make it easy to keep up with progress. I'd be interested to hear about any other (feasible) services people think would be useful to run at http://lv2plug.in Cheers, -dr

14 years, 9 months

[LAD] jack routing vs pulse routing

by James Morris

I'm familiar with JACK but not at all with Pulse, but while doing a little research to sum up various Linux audio APIs on a user group list I keep seeing claims* that at first sight suggest Pulse is capable of doing the audio routing with low latency that we know and love JACK for doing. Can someone sum up the differences between JACK and Pulse in this regard? James. * http://en.wikipedia.org/wiki/Pulse_audio#Features

14 years, 9 months

[LAD] Finding ALSA sequencer client/port numbers

by Fons Adriaensen

Hello all, after reading ASLA docs for some hours I've not found an answer to the following: Given the ALSA sequencer client and port _names_, find the numbers required to set up a connection (a 'subscription' in ALSA lingo). Anyone knows how to do this ? Ciao, -- FA

14 years, 9 months

[LAD] Max V. Mathews (1926-2011)

by Dave Phillips

Greetings, The subject line says it. Sad tidings. dp

14 years, 9 months

[LAD] Freeze when using threaded irq-handlers

by Niccolò Belli

-------- Messaggio originale -------- Oggetto: Re: [ANNOUNCE] 2.6.33.9-rt31 Data: Sun, 17 Apr 2011 18:26:47 +0200 Mittente: Niccolò Belli <darkbasic4(a)gmail.com> A: linux-rt-users(a)vger.kernel.org <linux-rt-users(a)vger.kernel.org> Il 13/04/2011 20:54, Jeremy Jongepier ha scritto: > 2.6.39 will integrate another very important part of the real-time > patchset though: > http://lists.linuxaudio.org/pipermail/linux-audio-dev/2011-March/030782.html If I enable it with the "threadirqs" boot parameter, it hangs few seconds after starting jack (using a Focusrite Saffire PRO 40) and I have to hard reboot. Where should I report the bug? Darkbasic

14 years, 10 months

[LAD] New release of jack_delay

by Fons Adriaensen

Hello all, A new release of jack_delay is available at <http://kokkinizita.linuxaudio.org/linuxaudio/downloads> > From the README: jack_delay 0.4.0 - 18/04/2011 ------------------------------- Jack_delay can be used to measure the round-trip latency of a soundcard. To do this, start the program and connect like this: jack_delay -> playback_port -> cable from soundcard output to input -> capture port -> jack_delay Jack_delay generates a signal consisting of 13 sine waves, measures the phase difference between the input and output for each of these, and computes the delay from those phase differences. The algorithm used is one developed originally for satellite ranging - that is measuring the distance between a satellite and a ground station. With a good sound card jack_delay will measure the round-trip latency with an accuracy of around 1/1000 of a sample. The assumption is that the delay is more or less independent of frequency. The actual value displayed is the one for a frequency of 1/16 of the sample rate. The phase measurement for this frequency of course only provides a result in the range of 0..16 samples. The other frequencies are used to extend this interval to 4096 * 16 samples, more than a second at 48 kHz. This release should be much less sensitive to frequency-dependent delay than the previous ones. The following options are avaiable (use jack_delay -h to see them): -O playback port connect output to named port. -I capture port connect input to named port. -E show excess latency instead of full latency. Using -E requires -O and -I, as the the computation depends on the latency values reported by jack for the ports used. The excess latency is the measured value minus the expected one, taking into account any corrections set by jack's -I and -O options. That is, if you have the right values for these options, then the value displayed with -E will be at most +/- half a sample. To determine the correct values for jack's -I and -O, set both of them to zero ('default' in qjackctl) and measure the latency using the -E option. Then set each of the -I and -O options to half the value displayed. Ciao, -- FA

14 years, 10 months

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Linux-audio-dev