[Freeswitch-users] Choosing a Codec.

Steve Underwood steveu at coppice.org
Wed Dec 23 05:55:00 PST 2009


On 12/23/2009 11:29 AM, David Knell wrote:
> On the other hand, a u-law WAV turned into L16 and then back to u-law to
> be sent down the line shouldn't suffer any alteration at all - if it
> does, the there's something wrong with the translation.
>
> The quality dropping over time is almost certainly down to something
> else.  Vinuth -can you get a recording to compare with the original?
>    
A linear->ulaw->linear->ulaw->linear->ulaw chain *should* only loose 
quality on the first cycle. However:
     - Many ulaw implementation are buggy, because they are based on the 
same broken Sun code. People are gradually waking up and fixing this. 
The broken
       implementations can loose considerable quality on each cycle.
     - Anywhere people fiddle with gains, you will loose quality on each 
cycle.

Steve





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