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Old 31st July, 2004, 08:01 PM
cadaveca cadaveca is offline
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Join Date: March 2004
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i said i wouldn't respond, but because you are veering so far from the truth, i can't let you misinform other people.
AC-3 is responsible for taking a PCM stream and COMPRESSING it to a smaller format. How it compresses it affects the way the sound comes out on the other end...like a mp3 encoded @ 64kbps sounds way worse than 192 kbps.
What makes AC-3 so great is that it DOES NOT REMOVE INFORMATION. IT RE-ENCODES IT to a different format....like taking your universal remote and getting it to do 4 commands with one button press.
the first pdf I attached was released by the atsc TELLING EVERYONE HOW THE ENCODING/DECODING WORKS. Now why would they release that information? You would think that Dolby would want their best assest kept secret. Well, they had to release it. They had to tell everyone how to be able to encode THIER OWN SOURCE MATERIAL IN WHATEVER FORMAT into AC-3 so it can be broadcasted by satellite, and to americans homes. It's LAW THAT ALL SOUND THAT WILL BE SENT by satellite WILL BE AC-3! LAW!
SO, with all this in mind, AC-3 HAS to be able to handle a variety of formats. otherwise every single person would need new equipment just so that they could watch tv. Although this would make electronics maufacturers really happy, we all know that it could never happen.
this all started in 1992. now you'll find the dolby label on almost every comsumer electronic out there. AC-3 is THE STANDARD. Dolby did quite a great thing. But they are not the only ones out there. but they all send their signlas via pcm.
what's that?ac-3 takes pcm signals,re-encodes it, and sends it away? Is dts not pcm?
of course you cannot plug a coaxial into a regular analogue jack and hear anything....your feeding a analogue line a digital signal. of course it's just noise. but digital to digital, no matter the format, will work. you can go coaxial/have a inline converter to optical, and have a seperate line for video, and still things will be in sync. why? all digital signals end up in the same place. in a codec soldered to a board. as long as the codec knows what's going on, everything works just right.
although most consumer electronics don't have this plug and play like ability, it's coming. there is no avoiding it now, as it's law. we are only about 18 months from an all-in-one cable that send both audio and video, as well as other data.
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Last edited by cadaveca; 31st July, 2004 at 08:09 PM.
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