AC-3 Question

[Nelson37]

I just learned that my Digital cable has Dolby 3.1, NOT 5.1. Bummer!
Now, Softencode accepts the file and creates an AC-3 that WinDVD recognizes as such and plays. So at least when they finally upgrade to true 5.1, I am ready.

My question is what is Softencode giving me, a prologic file in an AC-3 wrapper? It's not doing simulated surround or anything, is it? Any advantages to doing this? Sound seems a bit cleaner on record, my playback equipment is limited so evaluation is difficult. I could just encode as prologic rather than AC-3. And if I only have 3.1, I have no good reason to upgrade now. Read that as no way to convince my domestic financial advisor that we really need it.

[BJ_M]

dolby digital 3/1 is 5 channels if LFE is enabled which most likely it is ..

its not a prologic wrapper ...

i dont know of anyway to encode prologic with software -- i could be wrong ..

[Nelson37]

So is 3.1 the same as Prologic, or Prologic 2? All these sound formats and interchangeable terms are confusing.

SFAIK, tooLame will save a prologic-encoded file but can't create one from a stereo file. I was thinking AC-3 HAD to be true 5.1 but now I recall that 3.1 also qualifies.

Prologic = Left, Right, Center, one rear @ -20db, and sub

Prologic 2 = Left, Right, Center, 2 seperate rear at same volume level

Both the above are muxed into a standard stereo signal

Dolby Digital means an encoded, digital AC-3 file, other than that 3.1 seems to equal prologic without the volume drop and 5.1 equals Prologic 2.

Any correction or additions to this would be greatly appreciated.

[BJ_M]

Dolby Digital can be anything from 1 channel (well seperate channels vs. stereo channels) to 8 channels - i do it for a living ..

it is a lot better than prologic in any form ..

DTS is better sounding yet again .. but that is also an old debate ..


there is also seperate types of Dolby digital (and DTS) for consumer and cinema -- they are not only non compatable but completely different encoding ..

[Nelson37]

So is "Dolby three - one" actually Left, Right, Center, and Rear ( or Surround) PLUS an (optional?) LFE (or subwoofer channel, or is there a difference?)?

Is the dedicated subwoofer channel significantly different from my amp just switching all low-frequency sound to the Subwoofer?

I gather Dolby has a superior encoding methodology? as opposed to the difference being just Analog vs Digital.

Thank you for your response, it is good to have answers from a professional in the business.