Hi,
tisdagen den 09 december 2003 12.22 skrev Steve Harris:
> On Tue, Dec 09, 2003 at 09:25:42AM +0100, Clemens Ladisch wrote:
> > > > I seem to recall that it does, but that the packet size is smaller,
> > > > making the latency problem easier to deal with.
> > >
> > > Isoch - 1394 has a timer operating on the bus. This timer happens
> > > (roughly) every 125uS.
> >
> > USB isochronous transfers happen once per millisecond.
>
> OK, so its the difference between 44 or 45 samples per packet at 44.1kHz
> (USB) and 5 or 6 (1394).
>
> So, a plausible jack period of 64 samples will be 11 or 12 1395 packets,
> but always 125uS of jitter of course, (10 or 11 packets at 48k).
>
> I dont really have any idea how bad that is, its 8% of the availble time
> slot for processing the 64 samples.
>
> You could lessen the effect of the jitter by having triple-buffering in
> software, as in a 3x64 PCI soundcard - I dont know wether thats better
> than just going to 128 samples or not.
>
> FWIW, for my needs I rarely go below 256 samples/period anyway, even
> though my setup is capable of it, but I understand there are people who
> really need very low latency.
>
> At 256 samples/period the jitter is only 2.1% of the time slice, which is
> unlilkly to matter - cache temperature and so on has a far greater effect
> than that.
Though it is interesting debating the technical merits of firewire, for me,
atleast, it would be far more interesting to get it actually working. I'm
_very_ interested in utilizing these hardwares.
I googled a little last night, some people we all know popped up here and
there (Hi Steve, Mark and Bob).
There was a LAD message from 2001, someone who had been in contact with Yamaha
and it seemed they(Yamaha) where working towards making mLan a part of the
A&M standard (I think I got that right...not sure)... now... I'm not entirely
sure what this means. It seemed as the A&M standards also cost a lot of
money?
Do we have enough information to implement mLan support?
As I understand it, Bob Ham had/is working on implementing 61883 support for
Jack, which seems like it's needed for mLan, a layer below it perhaps? How
far has this come, is there something one can test somehow, what hardware do
one need?
Regards,
Robert
ps.
I'm cc:ing LAD as I'd like to move the discussion there. Remove LAU if you
respond to this.
ds.
On Martes, 09 de Diciembre de 2003 10:57, Gerrit Niestijl wrote:
> Hi,
>
> When i use timidity in alsa seq mode with a sequencer like muse or
> seq24, the timing is not very good. If i use fluidsynth the
> timing is much better. I would like to use timidity though, because
> of its support for the Midi Tuning Standard.
>
> Are others seeing this too? Are there any options or
> other ways to improve the timing for timidity?
try to start timidity with: -B2,8
Josep
hello linux audio enthusiasts!
reading lwn.net this morning i found that the linux journal has a new
linux audio column in their online edition, written by dave phillips.
the current issue is at
http://www.linuxjournal.com//article.php?sid=7283 .
the content of this first issue will not be news to you, since it's
basically a plug for the world's finest linux audio mailing lists, which
you already seem to know about :)
still, it's an interesting read, and it has had an effect already: about
30 new subscriptions (in addition to the usual continous growth) since
wednesday... (see http://www.linuxdj.com/audio/lad/subscribe.php3 .)
to all new readers: welcome aboard!
best,
jörn
--
To someone whose only tool is a hammer, each problem looks like a nail.
- Edsger W. Dijkstra, EWD838
Jörn Nettingsmeier
Kurfürstenstr 49, 45138 Essen, Germany
http://spunk.dnsalias.org (my server)
http://www.linuxaudiodev.org (Linux Audio Developers)
Hi all
I haven't really been following the discussion about the capabilities
patches etc, so bare with me if I have missed anything.
I am currently preparing an updated kernel, and am wondering whether any of
the proposed patches for a 2.4 kernel are stable enough to be usable. If
so, where can I obtain the patches?
Thanks
Luke
--
Luke Yelavich
AudioSlack Founder and head package maintainer
Audio software packaged for the Slackware Linux Distribution
http://www.audioslack.com
luke(a)audioslack.com
1. A short summary of changes
Support has been added for libsndfile. This allows to access
a number of new audio file formats such as W64, PVF and VOC
files. Integration with libaudiofile and MikMod has also
been improved. Bugs in the native Python ECI implementation
have been fixed. Rubyecasound, a Ruby ECI implementation, has
been added to the package. A serious memory-leak in list
handling functions of the C ECI implementation was fixed. This
bugfix also affects C++, Perl and PHP ECI implementations.
Compiling Ecamegapedal works again as the header files
missing from the previous 2.3.1 release are now again
included in the dist-package. Many minor bugs have been fixed.
---
2. What is Ecasound?
Ecasound is a software package designed for multitrack audio
processing. It can be used for simple tasks like audio playback,
recording and format conversions, as well as for multitrack effect
processing, mixing, recording and signal recycling. Ecasound supports
a wide range of audio inputs, outputs and effect algorithms.
Effects and audio objects can be combined in various ways, and their
parameters can be controlled by operator objects like oscillators
and MIDI-CCs. A versatile console mode user-interface is included
in the package.
Ecasound is licensed under the GPL. The Ecasound Control Interface
(ECI) is licensed under the LGPL.
---
3. Changes since last release
* Rubyecasound, a Ruby ECI implementation, has been added
to the package. Developer documentation can be found
at <http://eca.cx/eci>. Rubyecasound was developed by
Jan Weil.
* Some files were missing from the previous 2.3.1 release
dist-package. This caused the "make check" test procedure
to fail, and also prevented from compiling Ecamegapedal
against 2.3.1. In 2.3.2 the missing files are once again
included in the dist-package.
* Libsndfile support has been added to Ecasound
(development item 'edi-33'). Support for libaudiofile
has also been improved in this release. The user
can now compile in support for both libraries at
the same time. It is possible to use command-line options
to select which library to use for a given file. Similar
improvements have been made to the MikMod support.
See the ecasound(1) man page for more details.
* Some bugs in libsamplerate integration have been fixed.
Upgrading to libsamplerate version 0.0.15 or newer is
recommended. This release contains a few important fixes
that affect Ecasound. A few examples of resampling
with Ecasound have been added to the docs:
<http://www.wakkanet.fi/~kaiv/ecasound/Documentation/examples.html>.
* A severe memory-leak bug was found and fixed in the C ECI
implementation. This bug affects applications that heavily
use EIAM commands that return lists of strings. The C ECI
is used by C++, Perl, PHP and Python ECI implementations.
* Bugs in the native Python ECI implementation have been
fixed. The C-based Python ECI implementation is still
selected as the default, but you can override this with
the '--enable-pyecasound=python' option to configure.
Note, 'native' here means that ECI API is implemented without
linking to any Ecasound libraries. Instead the ECI implementation
forks 'ecasound' binary on the background and communicates with it
using pipes. This allows for clear decoupling between ECI apps
and specific Ecasound version. More information about ECI can
be found at <http://www.eca.cx/eci>.
Full list of changes is available at
<http://www.wakkanet.fi/~kaiv/ecasound/history.html>.
---
4. Interface and configuration file changes
None.
---
5. Contributors
Patches - Accepted code, documentation and build system changes
Jan Weil (2) -- rubyecasound ECI implementation, new docs
Mark de Wever (1) -- typo in libecasoundc-config usage
Kai Vehmanen (various)
Bug Hunting - Reports that led to bugfixes (items closed)
Fernando Pablo Lopez-Lezcano (1) -- preset.h not installed
Jan Weil (1) -- the ecacontrol.py bug
---
6. Links and files
Web sites:
http://www.eca.cxhttp://www.eca.cx/ecasoundhttp://www.eca.cx/eci
Source packages:
http://ecasound.seul.org/downloadhttp://ecasound.seul.org/download/ecasound-2.3.2.tar.gz
Distributions with maintained Ecasound support:
Agnula - http://www.agnula.org
AltLinux - http://www.altlinux.com
Debian - http://www.debian.org
FreeBSD - http://www.freebsd.org/ports/audio.html
Gentoo Linux - http://www.gentoo.org
Mandrake - http://www.mandrake.org
PLD Linux - http://www.pld.org.pl
SuSE Linux - http://www.suse.de/en
Contrib Packages and Add-On Distributions:
AudioSlack for Slackware - http://www.audioslack.com
PlanetCCRMA for RedHat/Fedora
- http://www-ccrma.stanford.edu/planetccrma/software
Thac's RPMs for Mandrake - http://rpm.nyvalls.seApps.kde.com packages for Mandrake/Redhat/SuSE
- http://apps.kde.com/rf/2/info/id/2146
Note! Distributors do not necessarily provide packages for
the very latest Ecasound version.
--
http://www.eca.cx
Audio software for Linux!
Jack 0.91.1 has been released.
Changes:
New iec61883 driver. Very experimental; this is just to get it out
there. 61883 is the standard for audio+midi over firewire. Run
configure with --enable-iec61883 to compile it. It requires libraw1394.
Added callback for notifying clients when entering freewheeling mode and
leaving it:
int jack_set_freewheel_callback (jack_client_t *client,
JackFreewheelCallback freewheel_callback,
void *arg);
Bugs fixed.
Compiler warnings removed.
Taybin Rutkin
I am cross-posting this to LAD, hoping to get some useful feedback.
Paul Davis <paul(a)linuxaudiosystems.com> writes:
> about that patch ... torben hohn wrote, some time ago on LAD (see his
> comment at the end). does anyone have time to check on this?
> > Have a look at linux security modules. In the 2.5 kernel the
> > patch you propose is not a patch, it is a kernel module.
I spent some time last night looking at...
(*) linux-2.6.0-test9 kernel sources (from Debian)
(*) SELinux 2.60-test6 sources from NSA, http://www.nsa.gov/selinux
(*) the Linux Security Modules web site http://lsm.immunix.org
As always with the web it's hard to tell the real stuff from the
vaporware. But, this stuff looks real to me. :-)
SELinux (Security-Enhanced Linux) is NSA's research project for
implementing DoD Orange-book security features as a pluggable kernel
module. Almost all of the SELinux modularization changes are present
in linux-2.6.0-test9. Their entire compressed patch for the
2.6.0-test6 kernel was only 1889 bytes containing 189 lines of context
diffs. By comparison, they also distribute an SELinux patch for
2.4.21, which is 209KB (compressed) containing almost 36,000 lines of
context diffs.
Internally, the 2.6 kernel exclusively uses `if(capable(CAP_foo))'
tests, AFAICT. That was already (mostly) true of 2.4. In 2.6, there
are pluggable security modules to control the semantics of these
tests. The vanilla test9 kernel includes a small example security
module, `security/root_plug.c', which tests for the presence of a
specific USB device at exec time, only allowing setuid if it is
present. It is only 143 lines long.
Domain and Type Enforcement (DTE) is another project using a loadable
security module. It seems to be aimed at Mandatory Access Controls
for partitioning the file access capabilities of root processes. The
idea is to run root daemons in a "Domain" that lacks the ability to
modify important system files like /bin/login and /etc/passwd,
frequent targets for evil crackers exploiting buffer overflows in
their victim daemons. ;-)
This leads me to believe that 2.6 *does* permit one to write a kernel
security module for selectively granting realtime permissions to
certain processes. The mechanisms provided are far more powerful than
necessary for that simple application. I don't know exactly what
realtime security policy should be implemented and how the underlying
mechanisms ought to be used, though I have some ideas.
But, the first step is to figure out if someone is already working on
this. My late-night googling didn't discover any existing project,
but surely someone is doing it by now. If not, I think we should
consider building and distributing one as part of JACK.
Comments?
--
joq