Linux-audio-dev February 2018

linux-audio-dev@lists.linuxaudio.org

12 participants
9 discussions

by Tim Goetze

http://quitte.de/dsp/caps.html The latest release of the caps audio plugin suite contains a number of bug fixes and improvements as well as changes intended to make it more suitable for low-power systems. http://quitte.de/dsp/caps.html#CHANGES Most notably, support for a variety of little-used features has been dropped, reducing the binary size by roughly a third. There's also a new plugin implementing simplistic linear emulation of several guitar amplifier loudspeaker cabinets with reduced computational complexity: http://quitte.de/dsp/caps.html#CabinetIII The compressor plugins now report current gain reduction: http://quitte.de/dsp/caps.html#Compress http://quitte.de/dsp/caps_0.9.24.tar.bz2 Cheers, Tim

6 years, 4 months

PipeWire

by Wim Taymans

Hi everyone, I'm Wim Taymans and I'm working on a new project called PipeWire you might have heard about [1]. I have given some general presentations about it during its various stages of development, some of which are online [2]. PipeWire started as a way to share arbirary multimedia, wich requires vastly different requirements regarding format support, device and memory management than JACK. It wasn't until I started experimenting with audio processing that the design started to gravitate to JACK. And then some of JACKs features became a requirement for PipeWire. The end goal of PipeWire is to interconnect applications and devices through a shared graph in a secure and efficient way. Some of the first applications will be wayland screen sharing and camera sharing with access control for sandboxed applications. It would be great if we could also use this to connect audio apps and devices, possibly unifying the pulseaudio/JACK audio stack. Because the general design is, what I think, now very similar to JACK, many people have been asking me if I'm collaborating with the linux pro-audio community on this in any way at all. I have not but I really want to change that. In this mail I hope to start a conversation about what I'm doing and I hope to get some help and experience from the broader professional audio developers community on how we can make this into something useful for everybody. I've been looking hard at all the things that are out there, including Wayland, JACK, LV2, CRAS, GStreamer, MFT, OMX,.. and have been trying to combine the best ideas of these projects into PipeWire. A new plugin API was designed for hard realtime processing of any media type. PipeWire is LGPL licensed and depends only on a standard c library. It's currently targeting Linux. At the core of the PipeWire design is a graph of processing nodes with arbirary input/output ports. Before processing begins, ports need to be configured with a format and a set of buffers for the data. Buffer data and metadata generally lives in memfd shared memory but can also be dmabuf or anything that can be passed as an fd between processes. There is a lot of flexibility in doing this setup, reusing much of the GStreamer experience there is. This all happens on the main thread, infrequently, not very important for the actual execution of the graph. In the realtime thread (PipeWire currently has 1 main thread and 1 realtime data thread), events from various sources can start push/pull operations in the graph. For the purpose of this mail, the audio sink uses a timerfd to wake up when the alsa buffer fill level is below a threshold. This causes the sink to fetch a buffer from its input port queue and copy it to the alsa ringbuffer. It then issues a pull to fetch more data from all linked peer nodes for which there is nothing queued. These peers will then eventually push another buffer in the sink queue to be picked up in the next pull cycle of the sink. This is somewhat similar to the JACK async scheduling model. In the generic case, PipeWire has to walk upstream in the graph until it finds a node that can produce something (see below how this can be optimized). Scheduling of nodes is, contrary to JACKs (and LADSPA and LV2) single 'process' method, done with 2 methods: process_input and process_ouput. This is done to support more complex plugins that need to decouple input from output and to also support a pull model for plugins. For internal clients, we directly call the methods, for external clients we use an eventfd and a shared ringbuffer to send the right process command to the client. When the external client has finished processing or need to pull, it signals PipeWire, which then wakes up the next clients if needed. This is different from JACK, where a client directly wakes up the peers to avoid a server context switch. JACK can do this because the graph and all client semaphores are shared. PipeWire can't in general for a couple of reaons: 1) you need to bring mixing of arbitrary formats to the clients 2) sandboxed clients should not be trusted with this information and responsability. In some cases it would probably be possible to improve that in the future (see below). This kind of scheduling works well for generic desktop style audio and video. Apps can send buffers of the size of their liking. Bigger buffers means higher latency but less frequent wakeups. The sink wakeup frequency is determined by the smallest buffer size that needs to be mixed. There is an upper limit for the largest amount of data that is mixed in one go to avoid having to do rewinds in alsa and still have reasonable latency when doing volume changes or adding new streams etc. The idea is to make a separate part of the graph dedicated to pro-audio. This part of the graph runs with mono 32bit float sample buffers of a fixed size and samplerate. The nodes running in this part of the graph also need to have a fixed input-output pattern. In this part of the graph, negotiating the format becomes trivial. We can preallocate a fixed size buffer for each port that is used to send/mix data between nodes. Exactly like how JACK works. In this scenario it would be possible to bring some of the graph state to trusted clients so that they can wake up their peers directly. As it turns out, the generic scheduling mechanism simplifies to the JACK way of scheduling and the option to do some optimisations (can directly start push from the sources, bundle process_input/output calls, mixing on ports is simplified by equal buffer sizes, ...) There is a lot more stuff that I can talk about and a lot of things that need to be fleshed out like latency calculations, an equivalent of JACK transport, session management, ... But this mail is already getting long :) I would very much like to hear your ideas, comments, flames, thoughts on this idea. I think I'm at a stage where I can present this to a bigger audience and have enough experience with the matter to have meaningful discussions. PipeWire is currently still in heavy development, many things can and do still change. I'm currently writing a replacement libjack.so[3] that runs jack clients directly on PipeWire (mixing and complicated scheduling doesn't work yet). Hope to hear your comments, Wim Taymans [1] pipewire.org [2] https://www.youtube.com/watch?v=6Xgx7cRoS0M [3] https://github.com/PipeWire/pipewire-jack

6 years, 6 months

Fwd: [Faudiostream-users] IFC-18: 2nd Call for Papers - International Faust Conference - Deadline Extended!

by Albert Graef

[Apologies for cross posting, please circulate widely.] *New submission deadline: March 26, 2018* 1st International Faust Conference - Johannes Gutenberg University, Mainz (Germany), July 17-18, 2018 The International Faust Conference (IFC-18: http://www.ifc18.uni-mainz.de) will take place at the Johannes Gutenberg University <http://www.uni-mainz.de/> of Mainz (Germany) on July 17-18, 2018. It aims at gathering developers and users of the Faust programming language <http://faust.grame.fr/> to present current projects and discuss future directions for Faust and its community. Participants will be able to share their work through paper presentations. A series of round tables on various topics will serve as a platform to brainstorm on Faust's features, semantics, tools, applications, etc. to determine future directions for this language. Open spaces for demos and workshops will be available for participants to openly share their ongoing projects with the rest of the community. As a special event, the winner of GRAME's Faust Open-Source Software Competition will be announced during IFC-18. IFC-18 is free and everyone is welcome to attend! *Call for Papers* We welcome submissions from academic, professional, independent programmers, artists, etc. We solicit original papers centered around the Faust programming language <http://faust.grame.fr/> in the following categories: - Original research - Technology tutorial - Artistic project report (e.g., installation, composition, etc.) Paper should be up to 14 pages in length, non anonymous, and formatted according to this template <http://www.ifc18.uni-mainz.de/misc/IFC-18-templates.zip>. *Submissions should be carried out via our EasyChair portal <https://easychair.org/conferences/?conf=ifc18>*. All submissions are subject to peer review. Acceptance may be conditional upon changes being made to the paper as directed by reviewers. Accepted papers will be published on-line as well as in the IFC-18 proceedings paper version. They will be presented by their author(s) at IFC-18 as 15 minutes presentations (+ 5 minutes for questions). Feel free to contact us if you have any question. *Important Dates* - Papers submission deadline: March 26, 2018 March 2, 2018 - Notification of Acceptance: May 5, 2018 May 1, 2018 - Camera-Ready Version: June 1, 2018 *Call for Round Table Topics* A series of round tables on the following themes will take place both afternoons of IFC-18: - Faust Tools (e.g., Architectures, IDE, Faust Code Generator, On-Line Services, etc.) - DSP in Faust and Faust Libraries (e.g., New Algorithms, New Libraries, Missing Functions, etc.) - Faust Compiler and Semantics - Other Topics/Open Session We solicit topic suggestions from the Faust community for each of these themes. Topics can be submitted by means of this Google form <https://goo.gl/forms/0fBYxk28jlRdtqRM2>. They will be introduced during the round tables by the session chair. *Contact* Please, address your questions to: ifc18(a)muwiinfa.geschichte.uni-mainz.de Conference website: http://www.ifc18.uni-mainz.de -- Dr. Albert Gr"af Computer Music Research Group, JGU Mainz, Germany Email: aggraef(a)gmail.com WWW: https://plus.google.com/+AlbertGraef

6 years, 12 months

linuxaudio.org is back online!

by Jeremy Jongepier

Dear all, We just enabled all mail services for linuxaudio.org again. All mailing lists are working again and mail can be sent and received for the linuxaudio.org domain. A short recap of what happened is that linuxaudio.org got compromised on January 29th, probably with a compromised private SSH key or password from an account with shell access. The attacker checked the kernel, saw that it was vulnerable to Dirty COW¹, pulled in an exploit and got root. This was quickly discovered by the IT department of Virginia Tech University that disconnected the server from the internet and started a forensic investigation procedure. As part of their IT security policy the server had to be reinstalled and everything had to be set up from scratch again. In the meanwhile I built an alternative setup and after some discussion we agreed on moving linuxaudio.org away from the Virginia Tech server. So linuxaudio.org got a new home after 15 years at Virginia Tech². We're very, very thankful that we could host linuxaudio.org on their servers and we can't stress enough how grateful we are for all the work that has been done on the side of Virginia Tech after the hack. linuxaudio.org now lives at Fuga³, a fully open source OpenStack⁴ cloud based in The Netherlands. Fuga is part of Cyso⁵, the company I work for. The linuxaudio.org ecosystem now consists of three separate servers, a web server, a mail server and a storage server. We rebuilt everything with portability and scalability in mind with a strong focus on security. You can never prevent passwords or SSH keys getting into the hands of hackers but we'll try to keep the servers as up to date as we can to narrow down the attack surface as much as possible. A big thank you to all those who helped out! It was quite a ride but it seems as if most part of the linuxaudio.org ecosystem is accessible again. If you find any web pages, downloads or other bits and parts that don't work properly then please let us know so we can take a look at it. Many thanks in advance and also many thanks for bearing with us! Best, Jeremy Jongepier root(a)linuxaudio.org ¹ https://dirtycow.ninja/ ² https://icat.vt.edu/ ³ https://fuga.cloud/ ⁴ https://www.openstack.org/ ⁴ https://cyso.com/en/

6 years, 12 months

LAC 2018: 2nd Call for Papers / Works

by David Runge

[Apologies for cross-postings] [Please distribute] LAC 2018: 2nd Call for Papers / Works Conference date: 7th - 10th June 2018 The Linux Audio Conference 2018 will be hosted at c-base, Berlin - in partnership with the Electronic Music Studio (TU Berlin) and Spektrum: https://lac.linuxaudio.org/2018 -------------------------------------------------------------------------------- The deadline for all submissions has been extended: March 15th, 2018 (23:59 UTC) -------------------------------------------------------------------------------- Submissions may include: - Papers - Posters - Workshops - Music Performances - Multimedia Installations For more details see the CFP on the website: https://lac.linuxaudio.org/2018/pages/cfp/ Looking forward to seeing you in Berlin! The Linux Audio Conference 2018 team

7 years

PipeWire, and "a more generic seeking and timing framework"

by Jonathan Brickman

Not really sure the subgraph is so good -- one of the things JACK gives us is the extremely solid knowledge of what it just did, is doing now, and will do next period. If I run Pulse with JACK, it's JACK controlling the hardware and Pulse feeding into it, not the other way around, because Pulse is not tightly synchronized, whereas JACK is. But if you can make it work as well, more power to you. Concerning seeking and timing, though, I have had to wonder. My impression of JACK for a long time (and more learned ladies and gentlemen, please correct) is that it uses a basically round-robin approach to its clients, with variation. I have had to wonder, especially given my need for this <https://github.com/ponderworthy/MultiJACK>, how practical a model might be possible, using preemptive multitasking or even Ethernet-style collision avoidance through entropic data, at current CPU speeds. It's chopped into frames, right? Couldn't audio and MIDI data be mapped into networking frames and then thrown around using the kernel networking stack? The timestamps are there...the connectivity is there...have to do interesting translations... :-) Could be done at the IP level or even lower I would think. The lower you go, the more power you get, because you're closer to the kernel at every step. -- *Jonathan E. Brickman jeb(a)ponderworthy.com <http://login.jsp/?at=02e47df3-a9af-4cd9-b951-1a06d255b48f&mailto=jeb@ponder…> (785)233-9977* *Hear us at http://ponderworthy.com <http://ponderworthy.com> -- CDs and MP3s now available! <http://ponderworthy.com/ad-astra/ad-astra.html>* *Music of compassion; fire, and life!!!*

7 years

CALL - Reminder + Extended Deadline - Thresholds of the Algorithmic - ALMAT @ BEK

by IOhannes m zmoelnig

Call for Applications: Workshop-in-Exposition: Thresholds of the Algorithmic Bergen (NO), June 2018. **Reminder and extended deadline: 23 February 2018** (sorry for x-posting -- please distribute) Algorithms have been used in music and sound art even before the emergence of “computer music” in the 1950s, but today we witness an entire new wave of interest, reflected in festivals, genres, publications and research projects. It is the very notion of algorithms that is shifting. They are no longer an abstract formalisation, but emerge from artistic praxis and experimentation and become entangled in it. Almat and BEK are happy to announce a call for participation in a workshop-in-exposition taking place in Bergen, Norway, June 2018. This will be a part of BEK and Notam’s ongoing series of workshops for advanced users. It is a hybrid format that places the workshop inside an exhibition context, where the exposed works and artefacts form the basis of the workshop’s activity. Instead of “closed works”, what is exposed to the general public are objects, sounds or installations that are open to engagement and reconfiguration during the workshop. Algorithms that Matter (Almat) is an artistic research project funded by the Austrian Science Fund FWF, PEEK AR 403-GBL, and based at the Institute of Electronic Music and Acoustics (IEM) in Graz, Austria. BEK and Notam are centers for innovation and use of technology in music and the arts in Norway. Both Notam and BEK have a strong focus on education, and strive to establish new goals and provide new impulses for current music technologists and artists. - https://almat.iem.at - http://www.bek.no - http://www.notam02.no - Full text of the call: https://almat.iem.at/assets/downloads/almat-bek_call2018.pdf - Application form: https://almat.iem.at/assets/downloads/almat-bek_form2018.pdf ## Theme and Format Thresholds are locations of transitions, points where one modality becomes another, where a qualitative change occurs. In physics the point where an aggregate state changes—the phase transition—is a distinguished transitional location were the properties of the adjacent states become evident. Similarly, in this workshop-in-exposition we want to study the properties of the algorithmic by putting ourselves in threshold positions and actively shape them. More than merely separating two sides, one can spend time on a threshold, move along a ridge, performing a tightrope walk while trying not to fall to either side. Situated within the Almat artistic research project, this event aims at bringing together practitioners and researchers in the field of digital art, sound art and computational aesthetics. The hybrid format of workshop-in-exposition puts on display works of the participants pertaining to the theme, and at the same time avails them for interrogation, discussion and reconfiguration during the week long workshop. The full call embeds a list of three different ‘thresholds’ from which the applicants should point out a specific one, that they recognise as being addressed by their own artistic work. This will act both as a point for further exploration during the workshop and as a bridge towards audience perception. ## Application Please read carefully the call and fill out the form provided at https://almat.iem.at/call2018.html and send it to almat(a)iem.at along with the required accompanying documents. We aim at a balance of gender and background of the applicants. Conditions: - Duration of exhibition: from 08 June to 17 June 2018 - Start date (in situ): 04 June 2018 (preparation and set up from 04 June to 08 June 2018) - End date: 17 June 2018 - Applicants must be present during the workshop. - Workshop fee must be paid by confirmed participants (see form) **Application deadline: 23 February 2018** (e-mail reception, 24:00 CET) If you have further questions, please do not hesitate to contact us at almat(a)iem.at. --- iem.at | kug.ac.at | bek.no | notam02.no | fwf.ac.at

7 years

test

by Benny Alexandar

Do I need to send test email ? -ben

7 years

LAD - 2nd test after 29/1...

by Rui Nuno Capela

LAD < 2nd test after 29/1... please ignore -- rncbc aka. Rui Nuno Capela rncbc(a)rncbc.org

7 years

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Linux-audio-dev February 2018