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

Michael T. Dean mtdean at thirdcontact.com
Wed Mar 15 23:17:58 UTC 2006

On 03/15/2006 11:37 AM, Bryan Bennetts wrote:

>I have a Leadtek PVR 2000 and the audio is directed from the card to the CD in 
>on the motherboard.  I was under the impression that the prologic aspect of 
>the tv audio should 'just work', however it does not.

There is no way for a receiver to detect Dolby Surround encoding (which 
can be decoded using Dolby ProLogic) in an analog signal.  Therefore, if 
you plug the audio out from your capture card directly into the 
receiver, the AFD will not turn on ProLogic for you.

A digital signal (i.e. via S/PDIF), however, may contain a flag that 
tells the receiver to use ProLogic decoding.  Therefore, if you plug a 
DVD player's digital audio output into your receiver and play back a DVD 
with a Dolby-Surround-encoded audio track, the receiver will probably 
automatically switch to ProLogic decoding.

Note, however, that I said, "may contain a flag."  The output from Myth 
doesn't contain this flag...  So, change the receiver from AFD to 
ProLogic (or Dolby Surround or whatever your receiver labels it) to get 
it to do ProLogic decoding.


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