[linux-audio-user] offline processing

LinuxMedia linuxmedia4 at netscape.net
Wed Feb 18 10:27:19 EST 2004

>>If oyu particularly want to use offline processing I would recommend you
>>look at ecasound, but it has a bit of a learning curve.

To answer the question about ecasound using LADSPA plugins... the answer 
(and example below) says yes (I think I actually tried it in the past).

Usually, I'll actually try out an example before I send to this list. 
But I just have too many projects right now to look up the 
LADSPA-specifc info that the following article points you to. But with 
the following information, I beleive a "direct to disk" (non-realtime) 
processing of a file with LADSPA and ecasound would look like this...

ecasound -i:DrySound.wav -o:DrySound_WithEffect.wav 

(on my system... a three and a half minute, 16bit, 48000 mono file took 
6 seconds to process the with a "built in" ecasound reverb. I'm assuming 
a LADSPA plugin would be about the same)

There was some mention on the ecasound list suggesting using LADSPA 
'unique id-number'. So you might want to try (as shown in the example at 
the end of this email)...

ecasound -i:DrySound.wav -o:DrySound_WithEffect.wav 
   (-eli flag instead of -el)

Keep in mind that if the "dry" file (starting file) is 1 channel (mono) 
file, and you want the resulting "effected" file to be mono also, you 
need to specify it on the command line (otherwise it will produce a 2 
channel (sterio) file by default (unless you have the ecasound "rc" file 
set for 1 channel... but it defaults to 2 channel unless you've actually 
changed the "rc" file with a text editor)...

ecasound -i:DryMono.wav -f:16,1,44100 -o:DryMono_WithEffect.wav 

(16 = 16bit... 1 = 1 channel... 44100 = 44100 sampling rate)

This following write up was from...

But you'll want to start here for more info about ecasound...
Ecasound home site

The write up...


Ecasound supports LADSPA-effect plugins (Linux Audio Developer's Simple 
Plugin API). Plugins are located in shared library (.so) files in 
/usr/local/share/ladspa (configured in ecasoundrc(5)). One shared 
library file can contain multiple plugin objects, but every plugin has a 
unique plugin name. This name is used for selecting plugins. See 
{HYPERLINK "http://www.linuxdj.com/audio/lad"} LAD mailing list web site 
  for more info about LADSPA. Other useful sites are {HYPERLINK 
"http://www.ladspa.org"} LADSPA home page   and {HYPERLINK 
"http://www.ffem.org/gdam/ladspa-doc/ladspa.html"} LADSPA documentation .

Same as above expect plugin's unique id-number is used. It is guaranteed 
that these id-numbers are unique among all LADSPA plugins.

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