At the Sounding Edge: Introducing seq24

This MIDI sequencer's simple interfaces and design put usability and functionality at the forefront.
The Performance Editor

The Performance editor (Figure 4) also is easy to use. Right-click and hold to bring up the pencil edit cursor, and left-click while holding to enter or delete a pattern. Concurrent patterns are allowed, and patterns can be added or removed in real time. Playback is either normal or defined by the loop points. The loop points are moved by selecting one of the L/R markers with the appropriate mouse button—left for L, right for R—and then clicking with the same button at the new location. The loop points also can be edited in real time.

Figure 4. seq24's Performance Editor

The three buttons in the top-right corner of the editor expand, collapse or expand and copy the material between the L/R markers. They are simple but useful tools for working with larger formal designs and elements of a composition.

File Management

Saving your work in seq24 is as uncomplicated as the rest of the program. Select File/Save As, give your work any name you like, with or without any extension (MID is best), click OK and that's it. From that point on, you simply can use File/Save. Reloading your work is equally simple.

seq24's native file format is the Format 1 standard MIDI file format. seq24 also can load a MIDI file and break its individual tracks into sequence containers. This feature is another neat musical extension to seq24's utility, offering new possibilities for material from other sequencing environments.


Despite its evident simplicity, there is more to see in seq24, but the program is easy to learn. Complete documentation is found in a brief text file named SEQ24. Also, starting the program with the --help long help option lists the available command-line options. The tooltips help is well-written and should clarify the interface even for complete beginners.

Power seq24

As a final tease, I leave you with the screenshot in Figure 5 to illustrate seq24 accompanied by some friends and helpers. seq24 manages its MIDI I/O internally (see above), and the synths it drives in the screenshot are all JACK clients. I use QJackCtl's audio connections panel to route the audio data to and from my selected synths and effects processors. In Figure 5, the output ports for QSynth and amSynth are connected to the JACK Rack running a single LADSPA plate reverb plugin. The processed output from the JACK Rack is connected to the ALSA PCM audio output ports. ZAddSubFX has its own effects, so its output is connected directly to the PCM ports.

Figure 5. seq24 and Friends

Thus, I have seq24 driving QSynth, amSynth, ZynAddSubFX and my SBLive's EMU10k1 synth (internal connection), with two of these devices routed through a software reverb unit. If you'd like to hear what this system sounds like you can visit this page for some brief examples in the OGG audio format. They're not complete pieces, but they should give you an idea of what can be done with some of the modern Linux audio and MIDI software now available.

The Future

seq24 can be invoked as a JACK transport client, giving it synchronization capability as either a JACK master or slave. Alas, my tests failed, which may be due to my JACK version. JACK sync is a cool feature, so I'll keep checking in on this one. Judging from the tarball's TODO file, other likely additions might include a few more edit functions and some randomization routines.

Final Remarks

seq24 is not a complicated program. It has been designed for speed, stability and efficiency. Admittedly, it is short on editing functions and long on usability, but its features are well chosen and musically useful. It's also incredibly addictive fun, as befits any serious musical instrument.

Dave Phillips is a musician, teacher and writer living in Findlay, Ohio. He has been an active member of the Linux Audio community since his first contact with Linux in 1995. He is the author of The Book of Linux Music & Sound, as well as numerous articles in Linux Journal.


Similis sum folio de quo ludunt venti.


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rick's picture

Any advice on setting up a Behringer FCB1010 midi foot pedal with seq24?? My fcb1010 is easy to configure for sooperlooper, etc., but seq24 is tough to get going, even with the documentation :O(

Slackware en Seq24

marco van der grient's picture

Afther some serious work I have seq24 working on my (slackware 10.2) dekstop. I have done the kernel hack for jackstart, because of the realtime benefits in normal user mode. An easy job, by the way!
I realy liked this artikel and it is inspiring to see that you can do so much with this sequencer and compatible friends, and that this collection of programs, organizesed with Seq24, beats sequencers as Rosegarden or even Cubase. It is realy inspiring for your own music.

A great benefit for me is not to be forced to use Gnome of KDE, since I realy do not like theze desktops because of there extensive use of resources, and that is reducing the quility of music (and joy?).

I have made slackware packages of all the programs and needed lib's. And will put them on a "webspace left". Thanx Dave Philips for done this (writing) job! And thanx for Seq24!
Greetings, Marco (I am a bassplayer, but in need for more digital music).

more additions (author's comment)

Anonymous's picture

I failed to note that the main page holds 32 sequence containers in what Rob calls a set. At the bottom right corner there's a spin button that accesses 32 sets, equalling 1024 sequence containers. Should be plenty for most purposes. :)

JACK support is reported as working by some users. Alas, I'm still not getting it happening with RH9, ALSA 1.04, JACK 0.99. Bummer.

completely off-topic

mimo's picture

A word of warning to musicians inspired by this article. Don't try this at home! I have worked with Linux since the early days of ALSA and with audio programs longer than some people can think and I have never seen more self-complacency than with the jack people. It might well be that jack works fine for its developers but for the average user (and even the more proficient one) it's a no-go. You install your realtime-lsm module, launch jackstart and all you get is

cannot get realtime capabilities, current capabilities are:
=ep cap_setpcap-ep
probably running under a kernel with capabilities disabled,
a suitable kernel would have printed something like "=eip"

That is with commoncap and realtime modules present. Now you wonder what the FAQ says: nothing, zero, null, void. The problem does not exist.

What are you talking about?

mike's picture

What are you talking about? im a newbie and this linux audio stuff rocks! It has all totally inspired me. I LOVE IT!!!! Ubuntu Studio rocks to! Thanks for the Great Articles Dave!!! Your teaching me a lot! You Rule!

have you ever listened about

Anonymous's picture

have you ever listened about realtime preemption patch? do you know why linux is linux and not windows, because you can tune your system to what you need, try a multimedia linux distribution like planet ccrma or agnula demudi and you got a system tuned for realtime, but obviously, the main distro's developers can't enable some features like this in their projects because of security issues (something microsoft have never mentioned, but already present in their window$), if you are not afraid from security problems you can simply run jack as root and no problems at all for the realtime preemption. but don't speak about something you don't know

Don't try this at home!

Carlos Pino's picture

Don't try this at home!

It could be better to say:

Don't try this at YOUR (mimo) home

For me works absolutely well.


Clinton's picture

If you are using realtime-lsm then you can just run jackd. Jackstart is only for when you have the patched kernel and not realtime-lsm.

clinton@drizzlehell:~/html/music$ jackstart -d alsa
jackstart: cannot get realtime capabilities, current capabilities are:
=ep cap_setpcap-ep
probably running under a kernel with capabilities disabled,
a suitable kernel would have printed something like "=eip"

clinton@drizzlehell:~/html/music$ jackd --realtime -d alsa jackd 0.99.0
Copyright 2001-2003 Paul Davis and others.
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details

loading driver ..
creating alsa driver ... hw:0|hw:0|1024|2|48000|0|0|nomon|swmeter|-|32bit
control device hw:0
configuring for 48000Hz, period = 1024 frames, buffer = 2 periods
Couldn't open hw:0 for 32bit samples trying 24bit instead
Couldn't open hw:0 for 24bit samples trying 16bit instead
Couldn't open hw:0 for 32bit samples trying 24bit instead
Couldn't open hw:0 for 24bit samples trying 16bit instead

Ta da, it works (make sure you are in the group that can use realtime-lsm, in Debian this defaults to audio).

some corrections (Author's notes)

Anonymous's picture

A few corrections:

When recording to a pattern the MIDI I/O button used should be the first button (as seen in Figure 3), not the third button (as referenced in the text).

ZAddSubFX == ZynAddSubFX

The page at has been updated to include some more details regarding setup and recording from the system described in "Power seq24". The examples themselves are also being continually updated (as I learn how to get more out of this setup).

Best regards,

Dave Phillips

seq24 in Mandrake contrib

Buchan Milne's picture

It would appear that the seq24 packages in Mandrake contrib are more up-to-date than Thac's packages (at least for 10.1, and 10.2 for which there are no Thac packages at present).

Mandrake 10.1 contrib has 0.5.1, Mandriva 2005LE contrib has 0.6.1.

While contrib is not officially supported, contrib packages are in bugzilla and do receive updates in community (at the maintainers discretion).

Thus, when packages are available in contrib, it is usually recommended to use them over 3rd-party packages.

(which is as much of the "Thac vs the community maintainers" issue as I will get into)