Linux-audio-dev

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2 participants
7501 discussions

[linux-audio-dev] resend: more about sync (was: rosegarden/ardour, ardour/adat, etc.)

by Aaron Trumm

Hi all. I've been trolling and testing various sync methods and I've noticed some questions popping up. Is it just me or is the linux audio situation a bit incomplete at this point with regard to information on that subject? It may just be that most of the programs are still struggling to develope sync techniques (MTC, MMC, ADAT sync, SMPTE, jack transport, etc. etc.), but also is there a relative lack of info/tutorials/etc? The reason I ask, is because not only for my sake, but for the sake of the community, I'd sure be glad to try and make a dent in that, maybe document some toots, or whatnot. of course, this all has to be in sync (no pun intended ;) ) with the development of the capabilities... I wish I had time to sort of type out something more detailed - I'll get to that sometime here (running short on time right this minute :) ) one basic hole I see at least in my understanding, is what the HECK is jack_transport, how does it fit in, etc.? that's ONE - there are lots of holes for me *laugh* another curious one is ecasound? it's the veteren around here in a lot of ways - does it sync to anything? ok well I'll wait for thoughts and then as soon as I can get a chance, I'll write something longer and sort of put out to y'all what I've found out, and see what holes can be filled - cheers (sorry for any unclarity in this email, unclarity is why I'm starting this thread! :) ) - Aaron www.nquit.com

21 years, 6 months

[linux-audio-dev] cdparanoia fails / audiofile comparer

by Juhana Sadeharju

Hello. Anyone would like to develop cdparanoia further? I ripped a CD two times with the following results: (== PROGRESS == [ !-------| 159332 00 ] == :^D * ==) (== PROGRESS == [ + + + | 159332 00 ] == :^D * ==) The errors are explaned this way: - Jitter correction required + Unreported loss of streaming/other error in read ! Errors are getting through stage 1 but corrected in stage2 Which error is more severe: "+" or "!"? Is "+" corrected properly? The problem is that the channels of other ripping are swapped at the point where "!" is located (but "!" may not have caused it). I don't know which one of the rippings is incorrect (they both could be incorrect). The channels also have one sample offset after the swap. The second ripping has "+" before the "!" point, but both rippings are indentical up to the "!" point. Would that mean that "+" is a harmless error and that thus the second ripping is correct? And that we should rewrite only the algorithm handling the "!" errors? In addition to rewriting "!" handling (or "+" handling if that caused the channel swap), I would like get out a printed list of errors. The error list could then be used in an audio editor for marking the errors with red color (say). Also an audiofile comparer program would be great to have: a program which finds matching regions. Now it was easy to compare the regions up to the "!" point with md5sum program, but it was difficult to compare the end part due misaligning. I compared them visually at a few random points. In such a comparer program each matching sample would match bitwise for this application, but they could match with an error tolerance if the application is to compare an original audio and an edited audio which is affected by dither noise (say). So, such a comparer would reveal what edits were done in an audio editor -- I have needed such a program a few times earlier. Regards, Juhana

21 years, 6 months

[linux-audio-dev] Pixmap slider tutorial?

by Adam King

Hi All, I'm still new to LAD so sorry if this has been asked before - is there anywhere online that has an introductory tutorial to creating custom pixmap sliders? I'm looking for a tutorial similar to the gtk dial tutorial on the gtk.org site. If anyone has a link or info I'd appreciate it. Cheers, Adam

21 years, 6 months

[linux-audio-dev] SB Live IR remote control codes

by Juhana Sadeharju

Hello. Below are control codes for the SB Live IR remote control. The remote could be used in music players, in Audacity, in Ardour, and any other software. We should have a standard format for an info file which tells the regions in audiofiles. Such info file (if exists) would tell where to jump when I press "1" or "next" in the remote. Regards, Juhana == cut == SB Live remote control codes ---------------------------- as given by "amidi -d -p hw:0,0" // Without "speaker" button hold down. F0 00 20 21 60 00 01 0A 41 44 51 2E F7 // 1 Number group F0 00 20 21 60 00 01 0A 41 44 71 0E F7 // 2 F0 00 20 21 60 00 01 09 41 44 09 76 F7 // 3 F0 00 20 21 60 00 01 09 41 44 51 2E F7 // 4 F0 00 20 21 60 00 01 09 41 44 21 5E F7 // 5 F0 00 20 21 60 00 01 09 41 44 1E 61 F7 // 6 F0 00 20 21 60 00 01 0A 41 44 11 6E F7 // 7 F0 00 20 21 60 00 01 0A 41 44 41 3E F7 // 8 F0 00 20 21 60 00 01 0A 41 44 6E 11 F7 // 9 F0 00 20 21 60 00 01 09 41 44 01 7E F7 // 0 F0 00 20 21 60 00 01 0A 41 44 21 5E F7 // stop Transport group F0 00 20 21 60 00 01 0A 41 44 1E 61 F7 // play/pause (>/||) F0 00 20 21 60 00 01 0A 41 44 3E 41 F7 // (|>) + slow F0 00 20 21 60 00 01 0A 41 44 7E 01 F7 // (|<) + previous F0 00 20 21 60 00 01 09 41 44 5E 21 F7 // (>|) + next F0 00 20 21 60 00 01 09 41 44 7E 01 F7 // (||>) + step F0 00 20 21 60 00 01 09 41 44 76 09 F7 // mute Amplifier group F0 00 20 21 60 00 01 0A 41 44 46 39 F7 // vol - F0 00 20 21 60 00 01 09 41 44 46 39 F7 // vol + F0 00 20 21 60 00 01 09 41 44 31 4E F7 // eax Menu group F0 00 20 21 60 00 01 09 41 44 41 3E F7 // options F0 00 20 21 60 00 01 09 41 44 6E 11 F7 // display F0 00 20 21 60 00 01 09 41 44 71 0E F7 // return F0 00 20 21 60 00 01 09 41 44 11 6E F7 // start F0 00 20 21 60 00 01 09 41 44 3E 41 F7 // close + cancel F0 00 20 21 60 00 01 0A 41 44 61 1E F7 // left (<<) Browse group F0 00 20 21 60 00 01 0A 41 44 2E 51 F7 // right (>>) F0 00 20 21 60 00 01 0A 41 44 5E 21 F7 // up F0 00 20 21 60 00 01 0A 41 44 31 4E F7 // down F0 00 20 21 60 00 01 0A 41 44 01 7E F7 // select/ok // With "speaker" button hold down. F0 00 20 21 60 00 01 0A 41 44 50 2F F7 // 1 Number group F0 00 20 21 60 00 01 0A 41 44 70 0F F7 // 2 F0 00 20 21 60 00 01 09 41 44 08 77 F7 // 3 F0 00 20 21 60 00 01 09 41 44 50 2F F7 // 4 F0 00 20 21 60 00 01 09 41 44 20 5F F7 // 5 F0 00 20 21 60 00 01 09 41 44 1F 60 F7 // 6 F0 00 20 21 60 00 01 0A 41 44 10 6F F7 // 7 F0 00 20 21 60 00 01 0A 41 44 40 3F F7 // 8 F0 00 20 21 60 00 01 0A 41 44 6F 10 F7 // 9 F0 00 20 21 60 00 01 09 41 44 00 7F F7 // 0 F0 00 20 21 60 00 01 0A 41 44 20 5F F7 // stop Transport group F0 00 20 21 60 00 01 0A 41 44 1F 60 F7 // play/pause (>/||) F0 00 20 21 60 00 01 0A 41 44 3F 40 F7 // (|>) + slow F0 00 20 21 60 00 01 0A 41 44 7F 00 F7 // (|<) + previous F0 00 20 21 60 00 01 09 41 44 5F 20 F7 // (>|) + next F0 00 20 21 60 00 01 09 41 44 7F 00 F7 // (||>) + step F0 00 20 21 60 00 01 09 41 44 77 08 F7 // mute Amplifier group F0 00 20 21 60 00 01 0A 41 44 47 38 F7 // vol - F0 00 20 21 60 00 01 09 41 44 47 38 F7 // vol + F0 00 20 21 60 00 01 09 41 44 30 4F F7 // eax Menu group F0 00 20 21 60 00 01 09 41 44 40 3F F7 // options F0 00 20 21 60 00 01 09 41 44 6F 10 F7 // display F0 00 20 21 60 00 01 09 41 44 70 0F F7 // return F0 00 20 21 60 00 01 09 41 44 10 6F F7 // start F0 00 20 21 60 00 01 09 41 44 3F 40 F7 // close + cancel F0 00 20 21 60 00 01 0A 41 44 60 1F F7 // left (<<) Browse group F0 00 20 21 60 00 01 0A 41 44 2F 50 F7 // right (>>) F0 00 20 21 60 00 01 0A 41 44 5F 20 F7 // up F0 00 20 21 60 00 01 0A 41 44 30 4F F7 // down F0 00 20 21 60 00 01 0A 41 44 00 7F F7 // select/ok Note: Creative did not give the group names. The buttons (<<) and (>>) in the browse group could be used for 4x backward and forward playing as well. Note: number 0 is alone on the line and next to the transport group. It could be used in the transport control. Note: speaker button makes no code itself but it works like the shift key. Why the button is not named "shift" because it works as "shift" button for all groups. Note: there is no other "shift" button. Note: "slow", "previous", "next", "step" and "cancel" are printed under the buttons. So, "||>" and "step" could have totally different meanings. == end ==

21 years, 6 months

[linux-audio-dev] deconvolver for IR creation anyone?

by Uwe Koloska

Hello, I am looking for a deconvolver, that is able to produce impulse responses from sinus sweeps (and especially the exponentially sweeping sine wave introduced by Farina). Do you have any suggestions or at least tips to start an implementation by myself? Recently I managed to use the mls tools from nwfiir to produce an IR of my microverb. I had to learn the hard way, that simple soundcards are not able to be used as MLS source because of the non linearities. Even a simple DA-AD loop gives a result wave that mls2imp cannot cope with. But an empty loop with an US-122 (unfortunately not with linux for now) gives something very near to a dirac impulse! The hunt for the linux convolution reverb has started ;-) Uwe -- voiceINTERconnect www.voiceinterconnect.de ... smart speech applications from germany

21 years, 6 months

[linux-audio-dev] [Fwd: Re: [linux-audio-user] Sounds Expo in the UK]

by Patrick Shirkey

Daniel asked for this to be forwarded... -- Patrick Shirkey - Boost Hardware Ltd. Http://www.boosthardware.com Http://www.djcj.org - The Linux Audio Users guide ========================================

21 years, 6 months

[linux-audio-dev] {draft} setgid problems with GTK for realtime audio (long)

by Jack O'Quin

{This is a draft of a note for the GTK developers, requesting them to soften their position on disallowing setgid. Please post comments and suggestions. It carries more weight coming from a group of us. Also, please tell me where this is should go.} {The note seems overly long. Suggestions for things to leave out? Perhaps I should post some of this on the web as a white paper, and send them a much shorter message pointing to it.} Rationale ========= A number of us in the Linux Audio Developers community[1] are trying to come up with practical ways of dealing with the security exposures inherent in realtime audio. Our problem is that many audio applications require realtime scheduling and memory locking privileges to achieve stable, low-latency performance. While not a direct threat to system integrity, these privileges easily allow anyone with a local login to accidentally or intentionally freeze the machine. In security jargon, this is known as "Denial of Service". For a dedicated Digital Audio Workstation system, the risk is generally acceptable. But, we want to do our best to minimize its effects. Historically, many Linux audio applications required users to login as root when needing realtime privileges. Large audio programs often include complex graphical user interfaces, digital signal processing, and multi-threaded buffer handling. Running all this as root leaves the system wide open to devastating security attacks. This is what we want to avoid. Solutions Considered ==================== Some packages, like the JACK Audio Connection Kit[2], have successfully used Linux kernel capabilities[3] to run realtime audio applications using an ordinary user ID with only the necessary permissions delegated. Unfortunately, the Linux kernel developers do not fully support this, because that mechanism currently has known security holes[4]. Consequently, kernels are shipped with it partly disabled. The 2.4 kernel requires users to make a two-line patch, then recompile and reinstall to enable this feature. As these problems are not likely to be resolved any time soon, we have been investigating other solutions. The 2.6 kernels provide a new Linux Security Module (LSM) mechanism[5]. With that, we can turn on capabilities without forcing all our users to patch their kernels. But, the security exposure in the capabilities mechanism remains. So, we are working on an experimental LSM for 2.6 that grants realtime privileges to applications based on several optional criteria[6]. The most secure option only grants realtime access to programs or users belonging to a specific group ID, such as `realtime' or `audio'. Ideally, our applications would be setgid to that group, so only realtime programs would gain access to these privileges. Problems with GTK ================= Unfortunately, audio applications using GTK cannot take full advantage of this option, because GTK refuses to run setgid. The unintended consequence of that policy is to *increase* our security exposure by forcing us to grant realtime privileges to all the programs of users who need them, when we would prefer to restrict access to just the audio programs, themselves. We have read with interest the rationale[7] given by Owen Taylor of the GTK development team for disallowing the use of setuid and setgid in GTK applications. Owen writes: In the opinion of the GTK+ team, the only correct way to write a setuid program with a graphical user interface is to have a setuid backend that communicates with the non-setuid graphical user interface via a mechanism such as a pipe and that considers the input it receives to be untrusted. This is a fine suggestion, and certainly one viable approach. But, it seems presumptuous to claim that it is the "only correct way". One cannot force the many existing Linux audio applications to be rewritten to follow this advice, and it is unclear that there is any good reason to do so. Since GUI threads generally use non-privileged scheduling, in practice realtime priority is restricted to the I/O and signal processing threads anyway. Requested Change ================ While sympathetic with the concerns and intentions expressed in Owen's document, we are not happy with the actual implementation. We want gtk_init() to stop checking that the group ID equals the effective group ID. If you really feel that some such test is necessary, then please disallow operation only when the effective gid is zero (`root' or `wheel' in most systems). Note that testing for specific user and group privileges does not conform to current POSIX thinking on the subject. The standard has adopted the term "appropriate privileges"[8] for describing the effects of the implementation-defined security mechanism. This was done to encourage adoption of more granular privilege implementations than the traditional monolithic Unix superuser approach. So, no matter what tests you make, on some modern systems you will not be able to detect when GTK is running in a privileged context. System security is evolving in directions that are outside the scope of GTK and cannot adequately be enforced by any user-level library. Despite good intentions, incomplete security checking tends only to make matters worse. Regards, -- Jack O'Quin Austin, Texas [1] mailto:linux-audio-dev@music.columbia.edu [2] http://jackit.sourceforge.net [3] http://ftp.kernel.org/pub/linux/libs/security/linux-privs/kernel-2.4/capfaq… [4] http://archives.neohapsis.com/archives/sendmail/2000-q2/0002.html [5] http://lsm.immunix.org [6] http://www.joq.us/realtime/README [7] http://www.gtk.org/setuid.html [8] http://www.opengroup.org/onlinepubs/007904975/xrat/xbd_chap03.html

21 years, 6 months

[linux-audio-dev] Linux Audio Developers's Conference #2: Call For Music

by Frank Neumann

Hi all, the following announcement gets sent to all of linux-audio-dev, linux-audio-user and linux-audio-announce mailing lists in order to reach as many interested parties as possible; I'm sorry if you receive this twice or even more often. I would be glad if we get a lot of participation from your side! Frank ----------------------------------------------------------------------- >From April 29th to May 2nd, 2004, the Institute for Music and Acoustics of ZKM Karlsruhe, Germany, will host the 2nd conference of the Linux Audio Developers (LAD). As a new feature there will be presentations of music in addition to technical talks. For this, we are looking for music that has been produced completely or mostly under Linux. We are looking for: * Interesting demos of sound synthesis, sound processing, etc. * "Classical" computer music compositions, to be played in a concert setting * Pieces from areas such as Electronica, Chill-Out, Ambient etc. If you would like to participate, please send your composition(s) to this address: Linux Sound Night ZKM, Institut fuer Musik und Akustik Lorenzstr. 19 D-76135 Karlsruhe Germany Please make use of one of the following media formats: - Audio-CD, DVD or CD-ROM Possible audio file formats: aiff or wav; mono, stereo or multi-channel; 44.1 or 48 kHz; 16 or 24 bit resolution. Please include the following items with your submission (in English): * A short commentary on the compositions * A short Curriculum Vitae * A completed and signed printout of the form available here: http://www.zkm.de/lad Deadline for submissions is February 29th, 2004. A jury will select the compositions that will be performed/played. The jury will award 3 grants to participants to contribute to their travel expenses. Terms and conditions for participation can be found in the form above. Up-to-date information about the conference is available here: http://www.zkm.de/lad -- Frank Neumann (Frank.Neumann(a)st.com), VIONA Development Center STMicroelectronics, Karlstraße 27, 76133 Karlsruhe

21 years, 6 months

[linux-audio-dev] reminder about Ecasound Control Interface

by Kai Vehmanen

Hello, for those new to the API, Ecasound Control Interface (ECI) is a _simple_ API for controlling the Ecasound engine. It certainly is not, and is not meant to be, a general purpose API, but it suits nicely to many small-to-medium-size tasks. General info about ECI can be found at: http://www.eca.cx/eci I'm writing this because the recently released Ecasound-2.3.2 added support for Ruby (contributed by Jan Weil). Prior versions already provided support for C, C++, elisp, Perl, PHP and Python. So quite a few in other words. :) Another thing to remember is that ECI apps can interact with JACK (including full transport support!), use LADSPA plugins for effect processing, and perform native ALSA audio i/o. Second reason I'm writing this now is that I just wrote a small app to monitor JACK transport position (very much like jack_showtime that comes with JACK), and it turned out to be an easy thing to do: --cut-- #!/usr/bin/env python from pyeca import * from time import sleep e = ECA_CONTROL_INTERFACE() e.command("cs-add jackmon") e.command("c-add jacmon") e.command("ai-add jack") e.command("ao-add null") e.command("cs-connect") e.command("start") while e.last_type() != 'e': e.command("get-position") curpos = e.last_float() if e.last_type() == 'e': break sys.stderr.write('JACK system pos %6.2f secs\r' % e.last_float()) sleep(0.2) --cut-- Converting the above to your favorite language is left as an exercise. :) PS If you replace 's/null/jack/' and add the line 'e.command("cop-add -el:djFlanger,0,5,0.5,50")' ... you've turned the script into a small JACK-Rack style app that uses Steve's DjFlanger LADSPA plugin. -- http://www.eca.cx Audio software for Linux!

21 years, 6 months

[linux-audio-dev] Linux Security Module for realtime audio

by Jack O'Quin

I've been experimenting with Torben's LSM for the 2.6 kernel, and the realtime group permissions mechanism we discussed. Naturally, there are some problems. The worst is that GTK-2 will not tolerate the use of setgid... (process:11284): Gtk-WARNING **: This process is currently running setuid or setgid. This is not a supported use of GTK+. You must create a helper program instead. For further details, see: http://www.gtk.org/setuid.html Refusing to initialize GTK+. This seems to totally invalidate the setgid approach we had discussed, at least for audio applications using GTK. QT does not seem to complain about setgid, though most of the reasons for avoiding it with GTK surely apply there as well. So, I modified Torben's LSM to check supplementary groups, and this seems to work fine. From a system admin perspective it's pretty good. I'm a member of group `audio', which was accomplished by adding my user ID (joq) to the appropriate entry in /etc/group... audio:x:29:joq Then, I loaded the LSM like this... $ sudo modprobe jackcapabilities rtgid=29 After that, all my processes have realtime privileges. I can run JACK under my normal user ID... $ jackd --realtime -d alsa I had to make a small change to JACK for this to work, so you'll need CVS sources to try it. Note that `jackstart' was not needed. Then, when I start various JACK applications they automatically acquire realtime privileges, too... $ alsaplayer -o jack & $ ardour & $ jamin & For reasons I cannot explain, this works without requiring the CAP_SYS_RESOURCE capability, a welcome but unexpected bonus. I would appreciate comments, feedback, and bug reports. If you want to try it, don't forget that it has received minimal testing. Neither I nor anyone else can promise that it will not adversely affect your system security or stability. Caveat emptor! -- joq

21 years, 6 months

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Linux-audio-dev