[Asterisk-Users] Asterisk native sounds now available!

[Kristian Kielhofner]

Adrian A wrote:
> If I understand this correctly, this sounds package is a subset of the 
> Asterisk sounds package.  Can I just copy the native sounds (eg. ulaw) 
> in the existing sounds directory and Asterisk will automatically use 
> them instead of the default gsm ones?  How does Asterisk pick which one 
> to play, does it know about the .ulaw extension?
> 
> 

Adrian,

	Not quite.  This is a re-implementation of the sound files provided 
with Asterisk.  It includes %100 of the prompts provided with Asterisk. 
  Some people also install the OPTIONAL asterisk-sounds package.  This 
includes something like 1400 extra prompts (all in gsm format, btw). 
So, asterisk-sounds (as in the tarball or on CVS) is a SUPERSET of 
sounds for Asterisk.

	Asterisk will automatically choose the least "expensive" sound file to 
playback based on what codec the current channel is using.  See "show 
translation" for more details.  Example:

channel: ulaw
prompt available in: gsm, ulaw
Asterisk will play: ulaw

channel: g729
prompt available in: gsm ulaw
Asterisk will play: ulaw

channel: gsm
prompt available in: g729 sln
Asterisk will play: sln

channel: g729
prompt available in: gsm
Asterisk will play: gsm (the only thing available - ouch!)

	In that last example, Asterisk has to convert the gsm prompt into 
slinear (internally) and then convert it to g729.  That increases 
latency (by probably at least 20ms in this case), reduces quality (two 
different loss based compression schemes), and uses CPU time.

	In short, Asterisk will play whichever prompt is cheapest, but if it 
really has to, it will play whatever it can find.  It uses the file 
extension to determine this.  See "show formats" too.

--
Kristian Kielhofner