Re: [ecasound] output speed and stdout

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Subject: Re: [ecasound] output speed and stdout
From: Kai Vehmanen (
Date: Tue Sep 07 1999 - 18:41:21 EEST

On Mon, 6 Sep 1999, Jeremy Hall wrote:

>> in all this? Anyway, you can synchronize std-output to realtime
>> by using an extra OSS-output target... So something like..:
> well, that sacrefices /dev/dsp for this use.

Hmm, of course I could add a "realtime-null-output" ;) device that
would limit the processing speed by simulating soundcard

> I have several computers in various parts of the house, connected to
> ethernet. Originally, this scheme was designed to allow multiple mp3
> receive this data and play it. There is a small delay as the signal
> routes through the house in ethernet, but that is on the order of 2 or 3
> miliseconds, hardly noticable.

What kind of ethernet hardware do you have? I didn't know it's
possible to get the network latency so low!

> so when the recording studio is in place, ecasound could act as an effects
> rack or multitrack processor. If one could send each track to a separate
> group, that would be ideal, because an ecasound at the other end could
> problems associated with this plan:
> 1: how do you fastforward or rewind individual tracks?

This is rather simple to implement, but coming up with a user-friendly
way to use this feature is another thing. I could use the "active
chain" concept that is used in command-line parsing. By default, all
chains would be automically active, but you could change this with
some command ("chainselect" ?) in the interactive mode. All commands
(setpos, rewind, forward, chain (enabling/disabling) would only affect
active chains... Better ideas?

> 2: how do you change panning or volume real-time on a running ecasound?

By adding amplify and pan effects and controlling their parameters.
I guess it would be useful to be able to change effect parameters
directly using interactive mode commands, but there again the problem
of designing a usable user interface to this.

One way would be to add a command setting effect values. The problem
is that this can get quite complicated as there can be multiple
chainsetups, each chainsetup can have multiple chains and each
chain can have multiple effects. And of course, to make matters even
more confusing, different effect have different numbers of parameters.

Another way to do it is generic controller sources. You create
generic conroller source "a", assign it to amplify effect and
then this way you can just change the value of "a" and ecasound
takes care of updating the actual effect parameters. With this
approach it would also be easy to control multiple parameters at
the same time.

> 3: how do you patch in effects inline as the stream is recording?

Hmm, could you explain this some more?

> 4: could a scripting language be developed so that each track could be
> "adjusted" automatically for a final product

Well, it won't be easy but is possible. Basicly you would need
timestamped versions of all interactive commands.

> 5: how does one synchronize all the tracks together?

This will be difficult. I'll have to think about this some more.

Kai Vehmanen ----------------------------- CS, University of Turku, Finland
 : email                       
 : audio processing for linux  
 : my music (ambient-idm-rock-...mp3/ra)

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