[Asterisk-Dev] Re: [Asterisk-cvs] asterisk channel.c,1.187,1.188

[Steve Kann]

Kevin P. Fleming wrote:

> Steve Kann wrote:
>
>> I've been meaning to chat with you about this.   So now, the only 
>> time that we go through SLINEAR when we wouldn't have before is in 
>> the alaw <-> ulaw case, since all the other translators have slinear 
>> on one end..
>
>
> That's correct. The only effective result of this change (other than 
> what you mention above) is that any application that copies frames 
> from the channel (ChanSpy et al.) now get them in SLINEAR when 
> transcoding is happening, rather than in the native format of one of 
> the two ends (depending on the direction). This saves transcoding 
> resources, since they don't have to be handled again on their way into 
> the listening application/channel.
>
>> But, forcing transcoding is definitely a bad thing, not just for 
>> performance, but also for quality, as you lose quality every time you 
>> transcode (and it certainly _is_ noticable).
>
>
> Absolutely, and I'm really surprised that nobody noticed this before 
> yesterday. Even then, what brought it to light was the inability to 
> pass-through G.729 without licenses on the box (thanks to JerJer and 
> drumkilla for bringing it to my attention). Nobody noticed that _all_ 
> pass-through (but not natively bridged) calls were being turned into 
> SLINEAR and back, rather than being left alone.


That just shows how much people are paying attention :)

-SteveK