[asterisk-users] GSM codec is a good choice ???

[drew einhorn]

On Tue, Feb 24, 2009 at 6:39 PM, David fire <ddfire at gmail.com> wrote:
> ?
> GSM is greate! there was a miss understood.
> if you transcode more than 90 in a core 2 duo you get a bad audio
> GSM to G729 or G711 to G729.
>
> G711 to GSM is ok, but you should test it.
>

The codec is fine, many multi core processors suck,
there are serious bottlenecks between the cores and the memory bus.

Everything is fine as long as there is room for all the data in the level n
cache, but if you have get it from level n+1 cache, or the memory bus,
by the time you get it, its too late.

Don't know how much memory is needed per call transcoded,
but when you multiply an increasing number of calls,
sooner or later you will exceed the limit.

If you want to see an amazing high school project that took
third place in the Siemens Competion,

http://www.cogito.org/Interviews/InterviewsDetail.aspx?ContentID=17633

These kids were wondering why they were having trouble getting the
expected performance from their model, and discovered it was a
limitation of their multi core processor.

-- 
Drew Einhorn