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Post by Hughes, G D on Dec 10, 2017 0:24:56 GMT -5
The other day I was going through the setting on my DVR and discovered that at some point the Xfinity now will output 1080P. That's news to me. Then I find where the audio output is either stereo or DD5.1. So, up till now, stereo has been converted to PLIIx 7.1 as my default is set to auto for that input. Well, I decided to try the DD 5.1 input and it got me wondering how the XMC-1 manages the DD5.1 to 7.1. It always indicates PLIIx from the DD5.1 which is the same is it does from Stereo but, the sound is quit different. Does it just take data from the surrounds to create the rear surrounds? If so why is it not still a DD format like EX or something? I just wonder, if the unit is going to process the DD5.1 to PLIIx 7.1, is it using the data contained in the DD to do so or is it converting to stereo then to PLIIx to get the 7.1? Am I better off to just start with the 2 channel or is there something to be gained from starting with the DD5.1?
Thoughts?
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KeithL
Administrator 
Posts: 9,937
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Post by KeithL on Dec 10, 2017 2:13:48 GMT -5
Under normal conditions (and default settings), the XMC-1 will do its best to match the incoming signal to your system. With a DD5.1 input, the only "proper" way to handle it is to decode it to 5.1 channels (using the specified Dolby Digital decoder). If you have a DD5.1 input signal, and a 5.1 channel system, the XMC-1 will decode that DD5.1 signal to 5.1 channels and you're all set. If you have a DD5.1 input signal, and a 7.1 channel system, the XMC-1 will decode that DD5.1 signal to 5.1 channels. Then it will use then use PLIIx to synthesize the extra two channels to make it into 7.1 channels. Because DD5.1 delivers "five real discrete channels" while PLIIx is only faking it, decoding the DD5.1 signal first is the "right" way to do it... and should sound better. The other day I was going through the setting on my DVR and discovered that at some point the Xfinity now will output 1080P. That's news to me. Then I find where the audio output is either stereo or DD5.1. So, up till now, stereo has been converted to PLIIx 7.1 as my default is set to auto for that input. Well, I decided to try the DD 5.1 input and it got me wondering how the XMC-1 manages the DD5.1 to 7.1. It always indicates PLIIx from the DD5.1 which is the same is it does from Stereo but, the sound is quit different. Does it just take data from the surrounds to create the rear surrounds? If so why is it not still a DD format like EX or something? I just wonder, if the unit is going to process the DD5.1 to PLIIx 7.1, is it using the data contained in the DD to do so or is it converting to stereo then to PLIIx to get the 7.1? Am I better off to just start with the 2 channel or is there something to be gained from starting with the DD5.1? Thoughts? |
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Post by AudioHTIT on Dec 10, 2017 12:53:29 GMT -5
I wish the XMC-1 had a “copy side to rear” mode (like Anthem) for these situations, it leaves the signal discrete, but moves the (phantom) image toward the rear.
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Post by Hughes, G D on Dec 10, 2017 22:35:20 GMT -5
Under normal conditions (and default settings), the XMC-1 will do its best to match the incoming signal to your system. With a DD5.1 input, the only "proper" way to handle it is to decode it to 5.1 channels (using the specified Dolby Digital decoder). If you have a DD5.1 input signal, and a 5.1 channel system, the XMC-1 will decode that DD5.1 signal to 5.1 channels and you're all set. If you have a DD5.1 input signal, and a 7.1 channel system, the XMC-1 will decode that DD5.1 signal to 5.1 channels. Then it will use then use PLIIx to synthesize the extra two channels to make it into 7.1 channels. Because DD5.1 delivers "five real discrete channels" while PLIIx is only faking it, decoding the DD5.1 signal first is the "right" way to do it... and should sound better. This was my assumption but I could not prove it because all I see it that it the output is PLIIx. On your other point, To my ears, I prefer the sound when derived from 2 channel for everyday TV watching but I am still on the fence about the way surround channels sound during moving watch. With limited time spent watching/listening to different sound tracks from TV shows and On-Demand stuff, I think the 2 channel to PLIIx tends to put a little more in the surrounds than it does from DD5.1 source. At least so far. It may depend a lot on what is matrixed into the 2channel to begin with. Or some other factors I am not aware of. You don't know what you don't know, right? Still learning and loving the XMC-1 |
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