[asterisk-users] Re: Choice of soundfile format

[John Marvin]

Martin Joseph wrote:

> Transcoding is a bigger hit then mixing as i understand it.
> 
> If all the conference members are using ulaw for example, then having 
> the playback material encoded in ulaw is the big winner.  If there are 
> different codecs connecting, then there is a lot of 
> decoding/mixing/recoding that will need to occur.

There is a misunderstanding here. The only time transcoding is not 
required is when data is just being "passed through", either from a data 
file (recording, Music on Hold, Voicemail, etc.) or from one channel to 
another, AND the format is the same.

However, once mixing is required, i.e. for a conference, transcoding 
will always be required because you can't mix compressed data. All 
channels have to be decoded to sLinear, mixed, and then reencoded.

John