Audio Question Stereo/5.1/Inputs???

[itms]

Hi all,

I have a technical question.

It appears to me that all of the capture cards (except HDTV) only offer left and right inputs for sound capture.

If I understand correctly, the sound is embedded into the mpeg2 file and then when I watch the file the sound is sent out my sound card which has an optical out to my reciever.

Will the sound from a transmission captured with only left and right inputs play out the left and right speakers only or will it play out my center channel speaker?

Thanks in advace.

[Lucas]

The L+R stereo sound going to your receiver is usually Dolby Prologic encoded(Movies and series) so your receiver will be able to decode the signal and send the appropriate sound to your speakers including the center speaker.

My receiver has Dolby Prologic, Dolby Prologic II, IIx and DTS NEO 6, all of which work in giving me multi channel surround from the stereo sound coming out of SageTV recordings.

I see no reason why you shouldn't be able to do the same.

[itms]

Lucas,

Thanks for the answer. I did not know that there was Prologic encoding contained within the left and right streams, I thought it was literally left and right. With this answer, I am a go for testing!

Thanks again.

[stanger89]

Yeah, ProLogic encoding (and some others like Circle Surround), logically place center and surround info into 2 physical channels. It's called "Matrix Encoding" Vs Dolby Digital (and DTS) which actually cary 6 separate channels.

Basically a Matrix Decoder (like the ones Lucas mentioned) will take the stuff that's common (in L and R) and move it to the center, and then move the "echoey" stuff to the surrounds (technically it looks a phase differences and other stuff to figure out where to place stuff).

ProLogic encoding will do that (make center info common to both and surround stuff out of phase) on purpose, but a decoder like DPL II, CS2, etc, can extract surround info from most any stereo source. And while I'm typing if you've got Logic 7 (only on Lexicon or Marantz) or DPL IIx, those will extract 7.1 individual channels from a stereo source, vs DPL which will only extract 4, or DPL II which can only do 5.1.