[LAD] Jack2 on DROPS/L4 (Diploma thesis) | towards a truly real-time capable FOSS audio distribution
micuintus at gmx.de
Thu Apr 16 16:43:45 UTC 2009
Dear Linux Audio Developers,
as indicated by Stéphane in his presentation  he gave at LAC2009 today, I
finally handed in my diploma thesis, which I announced here . You can
download the full text of the thesis here:
If you want to take a glimpse at the code, you can get a (still very dirty)
snapshot of the code here .
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
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
Kind regards --- and those of you who are in Parma: Have an interesting
conference and a great time in Italy! ---,
// This is only a temporal location, I will inform you about the final
location here as soon as the document is published there.
Fingerprint: 1A15 A480 1F8B 07F6 9D12 3426 CEFE 7455 E4CB 4E80
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