[mythtv-users] Not getting Dolby Prologic out of s/pdif

[Meatwad]

Steven Adeff wrote:

> when the mpeg group designed their audio compression algorithm they
> made certain that DPL would survive. Of course they could only
> guarantee it at a certain bitrate, but from what I understand they did
> put algorithms in that were DPL smart so that they would not remove
> any DPL information except when the bitrate made it necesary.
> 
> As well, from my understanding broadcast level DD encoding will never
> remove DPL information as they always use a bitrate that won't affect
> DPL.

A quick A/B test tells my trained ears that DPL2 encoding is passing 
thru myth just fine from Comcast at 384kbps. I'm not curious enough to 
start dropping the rate and listening some more. Maybe later.

Everyone will have a different experience depending on your providers 
infrastructure. A large market with an older cable plant will have 
multiple headends spread out around the city/suburbs and each headend 
will have racks full of these or a liscensees equivalent:

http://www.dolby.com/assets/pdf/tech_library/149_seu4_ce.Manual.pdf

Each one of these must be calibrated by a tech. Lot's of human error. 
I've traveled to a *lot* of markets and the quality of the encoding 
varies wildly. Fortunately, the techs here are on the ball and did an 
outstanding job.

The newer Dolby branded five channel AC-3 encoders have a PL2 encoder 
and is a no brainer if the facility is all-digital because the factory 
preset is the correct one and what Steve said above.

--
mw