Audio capture - DD5.1 and AC3 are my assumptions correct?

[andkiich]

I have an Laserdisc that I want to backup. It's audio is Dolby Dig. 5.1. Am I correct in my assumption that if I capture the audio stream in uncompressed format, that the signal still carries with it the encoding for the 5.1?

Other information. My Laserdisc player does NOT have a built in Dolby Dig. decoder, so it would just be coming straight out the RCA left/right. I was then wanting to convert the uncompressed audio to AC3.

I haven't run into this before as all the Laserdiscs I've done in the past have all just been stereo audio.

I understand that this might be a rather complex issue, so if a link somewhere that helps me understand this would be simpler that would be great as well.

[bugster]

The only way to capture an AC3 stream is either rip it straight from the disk as is usually done with DVD's or perform a full digital transfer using an optical or co-ax digital audio connection. The audio coming out of the RCA left/right from your laserdisc player is analogue stereo. This may contain analog Dolby surround sound info that can be handled by a suitable decoder but it is not Dolby Digital. So if your only audio capture method is via these RCA connectors, you will lose the original Dolby Digital soundtrack and get stereo with Dolby Surround. Is It worth trying to re-create the Dolby Digital soundtrack from this, IMHO, almost certainly not.

Hope this helps.

[txpharoah]

Is It worth trying to re-create the Dolby Digital soundtrack from this, IMHO, almost certainly not.

Yep. Same here.

[andkiich]

OK, thanks. I wasn't sure if the signals were converted to analogue and shipped with the rest of the audio or not.

As always, I appreciate your time and comments.

[katzenkreis]

But what if the Laserdisc-Player has an AC-3/RF-Output and is connected to an Device which is usually used to transform the RF-Output to a signal for the Coaxial-Input of an DolbyDigital-Receiver ?
Would a Soundcard with an coaxial-input allow me to capture the AC-3-Signal ?

[tarpot]

My guess, and it is a guess. Is that it would work. RF converters are going for quite strong money on ebay. There must be a reason.
That and the fact it sounds very sensible that this would be the case.

[flaninacupboard]

there's an extensive post on this somewhere, do a quick forum search and i'm sure you'll find it.

as a brief summary, a lot of people tried to do what you propose, but to no avail. the coax in puts on sound cards are designed to record PCM, not DD. consequently you'd be able to capture a DTS stream from an LD no problem at all, but DD is harder. i believe one of creatives' newer toys (soundblaster extigy perhaps) can do it. the other option raised was using a soundcard with 3 stereo inputs to record the sound after it has been decoded from your amplifiers pre-amp output.