The small but intrepid group of JACK 1 developers announce the release today of JACK 0.124.0, the latest version of JACK 1. This release features 3 major new features that are designed to make JACK easier to use and better in several ways, along with a large set of minor bug fixes and improvements. You can fetch the tarball release here. It has been tagged in the JACK 1 git repository as "0.124.0".
One of the "minor" bug fixes will make a huge difference for some users: if a particular JACK client crashes only the misbehaving client will be "zombified" - other clients will continue functioning normally (after a short delay). If you are developing JACK applications, this can make a huge difference to your day-to-day experience of JACK 1.
The Metadata API
It is now possible to define arbitrary metadata to be associated with
any JACK port or JACK client. This API lays the groundwork for more
useful naming of ports and clients (particularly those associated with
hardware), as well as many other features that developers have talked
about in a JACK context for several years. The full docs on the API
can be found here and there is
also a man page for
Builtin MIDI hardware I/O (on Linux)
For years, we have known that the performance of the -X seq and -X
raw options to the ALSA backend have left much to be desired. For
that reason, most users have been instructed to
This release of JACK 1 sees the transformation
The canonical way to invoke this new internal MIDI driver is
In addition, the old
It is worth noting that the server argument
Builtin Internal Client for using additional ALSA devices
Older versions of JACK have come with the tools
To address these two points, the zita-a2j/zita-j2a code has been merged into the tools part of JACK as a pair of internal clients ("zalsa_in" and "zalsa_out") that can be specified on the command line. So for example, this JACK command line:
jackd ... -I "USB Mic:zalsa_in/-dhw:USB,-r44100,-n2,-p512" ...will create an internal client called "USB Mic" that represents the ALSA device "hw:USB" using the ZITA alsa/jack bridge code, running at 44100kHz, with 2 periods of size 512. If you do not specify the period size or sample rate, then the values in use by the backend will be adopted. Audio being captured or played back via devices added to JACK in this way will be resampled with substantial accuracy and quality.
Note that the -I argument has been present in JACK 2 for sometime, but the new JACK1 implementation extends the semantics of its argument by allowing the user to specify a client name as well as arguments for the internal client code.
Both internal clients (zalsa_in and zalsa_out) will accept the -h
argument to show their possible arguments:
Since this new "multiple device" capability is implemented using JACK
internal clients, you can remove a given device by just unloading the
client using the long-existing but rarely
It is worth noting that these internal clients can be used with any Linux-based backend (ALSA, FFADO, OSS, Dummy, Netjack) to add additional ALSA-support devices to an instance of JACK.
Syntactic Sugar Version
To make the addition of extra audio devices to an instance of JACK
even easier, JACK 1 also features the new
This option does nothing more than translate its argument into an equivalent use of -I, so for example:
-A SBis equivalent to using both of these arguments:
-I SB/zalsa_in/-dhw:SB -I SB/zalsa_out/-dhw:SBAs with
Finally, note that these internal clients are theoretically compatible with JACK 2, and should work with that implementation of JACK once JACK 2 has a working internal client loading mechanism restored.
Complete Change List for 0.124.0
Major New Features
Notable Source Code Rearrangements
Bug Fixes, Updates and Other Enhancements
Jonathan Woithe, Adrian Knoth, Fons Adriennsen, Nedko Arnaudov, Torben Hohn, Paul Davis.
Thanks to David Robillard, Jonathan Liles and Filipe Coehlo for their participation in the design of the metadata API.
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On 22.01.2014 20:31, Paul Davis wrote:
> The small but intrepid group of JACK 1 developers announce the
> release today of JACK 0.124.0, the latest version of JACK 1.
And what a release it is judging from the notes. Awesome work..
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