Re: [LAU] Jack transport - was - Ardour/Muse Jack tempo lock

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To: <len@...>
Cc: Linux Audio Users <linux-audio-user@...>
Date: Sunday, August 10, 2014 - 5:11 pm

On 08/10/2014 06:24 PM, Len Ovens wrote:

...and port latencies! Sadly, many jack applications ignore those which
leads to offsets, even though they share transport position.

> Is there a record enable in there?

No, there isn't.

> It seems to me it would be worthwhile

It's not that easy.
Record enable is an application state not a position in time.
Rec-arm needs to allocate buffers, prepare files on disk etc etc. It's
not realtime-safe. For playback there's already a special state:
JackTransportStarting. Applications should acknowledge that they're
ready to roll before jack goes into "play". A lot of jack-clients forgo
this which is already trouble enough, though not directly harmful in
this case (just possibly out of sync playback).

Adding ranges (loop, punch), application state (rec-en), or even
varispeed support would likely increase the mess rather than solve
anything. All clients need to explicitly agree in order for that to work
properly.

Then, there's also the requirement: "We want to provide for ongoing
binary compatibility as the transport design evolves." [1] (IOW: "don't
break existing jack applications") which complicates the actual
implementation.

That being said, yes, it would be cool. Multiple independent transports
would be very nice as well, and I want a pony, too :)

ciao,
robin

[1] http://jackaudio.org/api/transport-design.html
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Messages in current thread:
Re: [LAU] Jack transport - was - Ardour/Muse Jack tempo lock, Robin Gareus, (Sun Aug 10, 5:11 pm)
Re: [LAU] Jack transport - was - Ardour/Muse Jack tempo lock, Fons Adriaensen, (Mon Aug 11, 10:06 am)
Re: [LAU] Jack transport - was - Ardour/Muse Jack tempo lock, Fons Adriaensen, (Wed Aug 13, 10:59 am)
Re: [LAU] Jack transport - was - Ardour/Muse Jack tempo lock, Fons Adriaensen, (Wed Aug 13, 9:28 pm)
[LAU] control surface design - was - Jack transport, Len Ovens, (Wed Aug 13, 6:13 pm)
Re: [LAU] control surface design - was - Jack transport, Fons Adriaensen, (Wed Aug 13, 9:49 pm)
Re: [LAU] control surface design - was - Jack transport, Will Godfrey, (Thu Aug 14, 6:46 am)
Re: [LAU] Jack transport - was - Ardour/Muse Jack tempo lock, Fons Adriaensen, (Wed Aug 13, 11:26 am)