[linux-audio-user] some notes regarding sync (JACK, MTC) under Linux

Kai Vehmanen kai.vehmanen at wakkanet.fi
Thu Dec 18 12:03:54 EST 2003

On Thu, 18 Dec 2003, Dave Phillips wrote:

>     Ecasound also works nicely with JACK but I haven't tested all the 
> transport functions yet. I just realized that ecasound should be able to 
> rewind to start under JACK. Kai, am I right about that ? Where can I 
> find a summary of ecasound's current JACK capability ?

Yes, Ecasound has full transport support meaning it both reacts to and
sends transport events by default (i.e. no need to specify anything on the
command-line assuming you have at least one JACK input/output in the
chainsetup). Same applies to Ecamegapedal, it too is fully transport

Everything is documented in the man pages and the user's guide:


See especially the section '7.6.3 Transport Control' in the user's guide.

A short example:

# - start showtime (comes with JACK) to see the JACK-wide 
#   transport state
console1> jack_showtime

# - start ecasound with mp3 playback
console2> ecasound -i foo.mp3 -o jack_alsa -c

# - start processing
ecasound> start

# - check the 'console1' window, you should see the transport
#   rolling

# - reposition using jack_transport (another util that comes
#   with JACK)
console3> jack_transport
# - locate to pos 10sec (if srate=44100)
jack_transport> locate locate 441000

# - switch back to ecasound and rewind to start
ecasound> setpos 0

... and so on. Everything works in real-time, and it doesn't matter which 
client you use for making transport state changes.

 Audio software for Linux!

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