[asterisk-users] Use the NEW ulaw/alaw codecs (slower, but cleaner)

John Todd jtodd at digium.com
Mon Nov 17 12:08:09 CST 2008

On Nov 11, 2008, at 3:44 PM, Steve Murphy wrote:
> On Tue, 2008-11-11 at 16:11 -0700, Wilton Helm wrote:
>> I'm a bit puzzled, also, having implemented ulaw and alaw in an
>> embedded application.  Each can be done with a 16 Kbyte table in  
>> about
>> 0 time with no errors.  There are probably tricks that will cut the
>> table down by 2 or 4 X for a small cost in CPU cycles.  The inverse
>> requires 256 16 bit words.  I thought ulaw and alaw were pretty much
>> no brainers.  I don't know of any gottchas.  Why anyone with more  
>> that
>> a few K bytes of total system memory would even consider anything
>> other than a lookup table is beyond me.
>> Wilton
> Wilton--
> AFAIK, the current algorithms (old & new) are indeed table lookup.
> It wouldn't hurt for you to do a code review on them, you might
> be able to improve them...!
> murf

For those of you interested in a slightly longer discussion here,  
there is discussion (Nov 14) on the voip-users-conference about this  
and many other things:



John Todd
jtodd at digium.com        +1-256-428-6083
Asterisk Open Source Community Director

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