Linux-audio-dev April 2009

linux-audio-dev@lists.linuxaudio.org

63 participants
44 discussions

by James Warden

Hello, Just joined the list. I was toying with the following idea: take jamin's graphical multiband EQ and reshape it into an LV2 plugin. Is this a redundant idea in case someone else is already working on something similar ? Just let me know before I start looking into this. Cheers, J.

15 years, 11 months

Linux Plumbers Conference 2009 CFP

by Lennart Poettering

Heya! Doing (audio) infrastructure work on Linux? If so, please make to sure to join us at the Linux Plumbers Conference 2009 in Portland/Oregon in September. I will be doing an Audio track there and would like to make sure that everyone who does audio infrastructure work submits a paper, or at least attends, or maybe just knows about this conference! It's a conference about the kernel-userspace interfacing, about the lower levels in our software stack. Last year we had a very successfuly track about Audio and this year we will hopefully have a successfuly track again. Last year among the speakers we had Takashi Iwai (ALSA), Jonathan Woithe (FFADO) and me (PulseAudio). This year, we'll hopefully have YOU as well! To get an idea of the conference, here's a writeup of last year's track available from LWN: http://lwn.net/Articles/299211/ More details about the conference you can find here: http://linuxplumbersconf.org/ The full CFP is available here: http://linuxplumbersconf.org/2009/2009/04/lpc-2009-call-for-proposals/ Spread the word, Lennart -- Lennart Poettering Red Hat, Inc. lennart [at] poettering [dot] net ICQ# 11060553 http://0pointer.net/lennart/ GnuPG 0x1A015CC4

15 years, 11 months

my basic in-game audio xsynthesisx api

by james morris

Hi, Just a post to say I got the LADSPA working with SDL for my game. I've scrapped the synthesis idea at the moment, but might go back to it. The 1st stage can be downloaded from: http://www.jwm-art.net/XorGramana/XorGramana-0.0.9_19-04-2009.tar.bz2 If you have spare time on your hands, could you give the code the once-over and offer any suggestions/criticism/advice? Cheers, James. relevant files: smixer* audio* sfx* ladspa* further info: The mixer code started off based upon the mixer from David Olofson's DT-42 but has been converted to mix floating point data instead. It uses libsndfile to load audio (flac) and libsamplerate for converting audio during playback for different speed/pitch (but this has not been incorporated into the api, the ratio is set randomly). LADSPA plugins used are from SWH and C* (CAPS) sets. The ladspa_loader code is based upon that used in my Wav Composer Not Toilet. Still a lot more to do yet. Migrate effects processing from audio_gen.c to smixer.c next job. The 1bar sequence/loop is hard-coded. Needs a sequencer, probably will base it loosely upon DT-42 to begin with. Plan is to have player position and immediate surroundings influence the effects settings and mute voices/add extra hits/switch loops etc. Free-up some allocations upon exit etc. Info about the game itself can be found at: http://www.jwm-art.net/XorGramana -

15 years, 11 months

audio recording through pipe using mplayer and sox sometimes has incorrect speed

by Arnold Obdeijn

Hi all, I am using mplayer, sox and tee to capture streaming internet radio and send it both to an audio recognition program and to a file (recording). This is how I do it: mplayer -playlist {url} -nocache -af volnorm -msglevel all=1 -nolirc -vc dummy -vo null -ao pcm:file={$fifo1} & sox -S {$fifo1} -c 1 -r 8000 -t wav - resample | tee {$recording} | tee {$fifo2} & ...... $fifo1 and $fifo2 are named pipes, $fifo2 is processed by an audio recognition program. The idea is that the audio is converted to low quality wav (8000Hz mono) after which it is fed to the program and simultaneously recorded. This works great most of the time but sometimes the recording is too long/slow or too short/fast. Sometimes the speed is slighly wrong and sometimes it is terribly wrong. When the speed is too slow, I notice that the file is also much larger and if I open the file in Audacity, the program tells me that the duration of the recording is for example two hours in stead of 1 hour (when the speed is twice as slow as it should be). Below is a list of three recordings that are the product of this setup. The middle one is larger and when I play it back it is three times too slow. 55M 2009-04-09 07:00 /data/station_recordings/48_20090409-0600.wav 152M 2009-04-09 06:00 /data/station_recordings/48_20090409-0500.wav 55M 2009-04-09 05:00 /data/station_recordings/48_20090409-0400.wav My guess is that it has something to do with the sample rate. If anyone has any idea where this goes wrong or what I could do to try to fix it, please let me know. Arnold.

15 years, 11 months

Jack2 on DROPS/L4 (Diploma thesis) | towards a truly real-time capable FOSS audio distribution

by micu

Dear Linux Audio Developers, as indicated by Stéphane in his presentation [1] he gave at LAC2009 today, I finally handed in my diploma thesis, which I announced here [2]. You can download the full text of the thesis here: <http://www1.inf.tu-dresden.de/~s3418892/diplom.pdf> [3]. If you want to take a glimpse at the code, you can get a (still very dirty) snapshot of the code here [4]. The abstract of the thesis: > Several available free software audio solutions were analyzed, and > Jackdmp—a C++ reimplementation of the renowned JACK Audio Connection > Kit—was selected as the most appropriate solution for a real-time audio > architecture on DROPS. The JACK sound architecture provides the lowest > processing latency possible on a desktop computer for a given set of sound > card parameters. It reduces the latency jitter caused by software to zero > and synchronizes streams at sample accuracy. > A real-time admission scheme for JACK clients is proposed. > The execution time of different typical JACK clients was analyzed with > measurements to validate the assumptions the proposal is based on, > but also to gain further knowledge about their timing behavior. > The measurements showed that the condition set by Paul Davis—the > time to process a client must be a linear function of the buffer size—holds > for all tested clients. > Jackdmp was ported to DROPS. The developed design of the port and its > implementation is documented here. Measurements showed that—although > the real-time performance of the Linux kernel is continously being improved > in the mainline and on special external branches—DROPS can provide a > signaling latency that is two times lower on average than the values that > can be achieved on the same machine running with a low latency patched > Linux kernel. Thus, it can be stated that DROPS is well-suited for > real-time audio processing and that the pursued path to use it as the > foundation of a truly real-time capable audio workstation should be > followed. As of the project's future: I will try to get the ALSA driver and the connection with L4Linux working until the presentation of the project (no date set so far, but probably in 2--4 weeks or so). If all works well, we will consider releasing a demo disc and / or a Youtube demonstration for interested developers and power users of the system then. And then we'll see :). Kind regards --- and those of you who are in Parma: Have an interesting conference and a great time in Italy! ---, micu =============================================================== [1]<http://linuxaudio.de/lac2009/JACK2_LAC_2009_slides.pdf> [2]<http://lists.linuxaudio.org/pipermail/linux-audio-dev/2008-July/021384.html> [3]<http://www1.inf.tu-dresden.de/~s3418892/diplom.pdf> // This is only a temporal location, I will inform you about the final location here as soon as the document is published there. [4]<http://www1.inf.tu-dresden.de/~s3418892/code_snapshot_(still%20dirty).tar.gz> -- GnuPG: https://www1.inf.tu-dresden.de/~s3418892/micuintus.asc Fingerprint: 1A15 A480 1F8B 07F6 9D12 3426 CEFE 7455 E4CB 4E80 <<</>> https://wiki.c3d2.de/Benutzer:Micuintus

15 years, 11 months

Building 'rhumba box', need square inches of ports data.

by Gene Heskett

Greetings; I'm building a rhumba box not exactly like anything I've been able to google up on the net. But I saw one a week ago that I thought worked very well as an acoustic standup bass substitute when it was close miked. My boxes panels are 5.2mm birch plywood, with double rabbeted cherry glue strips, and except for the sound port holes in the front panel, will be air sealed for best resonance. Total capacity then is 3.535 cu feet. My question is, given that the port holes will be a larger one in the dead center of the front panel, and two smaller ones flanking it, splitting the space so the smaller ones will be centered on 1/2 the distance from the center point of the center hole, sort of a | o 0 o | where the vertical lines are the ends of the box by its longest measure. Is there a formula for lowest frequency vs cubic feet that is commonly used to determine the sizes of these 'sound' portholes? Thanks all. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Yes, but every time I try to see things your way, I get a headache.

15 years, 11 months

Utility to read SMPTE LTC "audio" time-code

by Pau Arumí

Hi all, I'm facing the need of converting SMPTE LTC time-code* (encoded in an audio stream) into MTC timecode, to then route to other applications. Does anybody know a Linux application for that, or a library to decode that audio? Any advice will be appreciated. Thanks, P * http://www.philrees.co.uk/articles/timecode.htm#wave

15 years, 11 months

LAC2009 countdown

by Fons Adriaensen

Hello all, *** Latest news from Parma *** Joern N. has been here the past few days to get the streaming running and things look really good. We should have high-resolution and stable streaming, better than ever before. The streaming server homepage is at http://lac.stackingdwarves.net (IP 78.47.233.27, both on port 80 an 8000/tcp) There are two LAC chatrooms at irc.freenode.net: #lac2009 for discussions about the current paper/concert #lac2009-piazza for off-topic discussions and socializing. Remote participants are advised to join the first. They will then be able to take part in the Q&A session at the end of each presentation. See you soon in Parma ! -- FA & JN

15 years, 11 months

Travel from Milan Malpensa to Parma on wednesday evening

by Pieter Palmers

Hi all, I seem to have put myself in a brilliant position... My flight lands at 22:30 in Milan Malpensa airport, meaning that I can't make the last train from Milan to Parma. I have two possibilities: either stay a night in Milan and take the morning train, or rent a car in Malpensa, drive it to Parma and drop of it there the next morning. I've done the accounting for both scenario's, and the first one would come down to 100eur, while the car rental would set me back about 120 eur. Therefore I'm probably going to rent the car as it saves me a lot of hassle. But before booking it, I'm wondering if there are other people that might have the same issue. If so, a split fee would make things even more interesting (at least for me ;). Greets, Pieter

15 years, 11 months

[ot] Electrical Plugs in Italy

by Steven Yi

Hi All, Sort of off topic but I was having a hard time figuring this out: will electrical plugs that work other parts of Europe work in Italy as well? I am thinking the two circular prongs adapter. I have some adapters for when I was in Poland and Germany, but looking online it seemed like the adapter is slightly different in Italy but wasn't quite sure if the adapter I have will fit. Thanks! steven

15 years, 11 months

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Linux-audio-dev April 2009