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List:       kde-multimedia
Subject:    Re: Recording PCM audio with aRts
From:       Rik Hemsley <rik () kde ! org>
Date:       2001-06-10 14:04:49
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#if Stefan Westerfeld

> aRts currently uses no explicit selection of input sources, neither
> for midi nor for audio. Rather the current strategy is through the
> (Audio|Midi)Manager objects. This works like that:
> 
>   1. you start recording (playing), describing what you do
>
>   2. there are predefined points where you can record data from (play
>   data to),which the user can connect your application to through
>   artscontrol
>
>   3. the next time your application records (plays) again, it will be
>   connected to the same point again
> 
> It might be that you might want to change something in there, but
> thats the way it works right now.
 
This sounds to me like you're saying it's impossible to select an input
source with the aRts API and that the user would have to run artscontrol
to choose an input, right ? This isn't very nice for the user, as they
would probably prefer to just start the audio recording program, pick
an input (mic/line-in/cd/whatever) and press record.

> * opening, reading, closing:
> 
> Well, recording is still somewhat on the aRts TODO list, but here is an
> overview what works and what does not.
> 
> A. recording with server-side objects
> 
> Creating a Synth_AMAN_RECORD (which does that AudioManager thing), and
> connecting it to a Synth_CAPTURE_WAV is the simplest style of
> recording.  It will create a wave file in /tmp/mcop-<username>/... - I
> did hardcode that for now because of security considerations (what if
> you get an .arts file by mail that "records" some file which already
> exists and thus overwrites it? or creates a file which you - as
> stupid user - will never find again?).

You say you hardcoded the location that is saved to - so how would I go
about working around this ? Saving in /tmp isn't very useful.  My /tmp
is in RAM :) Also, I'll want to monitor the input with level meters, so
the user can see that their input is working. If the data is going
directly to a file behind my back, I won't be able to do that.

> So... as conclusion I'd say, it would be great if you write that simple
> recording application (we really really need that), and fix things on
> the way. (/me currently always uses artsbuilder with .arts files to do
> recording, which is probably not the ideal thing).

Sorry, I don't want to spend a lot of time learning about aRts internals
and fixing stuff, I just want to write very simple audio recording app.

If aRts doesn't support recording properly yet, that's ok, I'll just
drop the idea.

Rik

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