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Discussion Starter · #1 ·
While some stuff is encoded in 5.1 a lot isn't. Does 5.1 sound accurate on 7.1 systems? It seems like there would be some sort of distortion or it wouldn't sound quite right.


Edit: I meant 5.1 audio not video
 

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Not sure what you mean by "distortion", but...


If you were using only 2 surround speakers, placed along your sides and slightly behind you (±110-120°), some sounds would image at your sides while other sounds would phantom image in between (appear to be coming from behind you).


Of course, you have to be sitting in the sweet spot to hear this directionality. If you're sitting left or right of centre, then the sounds you were hearing behind you will collapse to the nearest surround speaker.


When you play back a 5.1 soundtrack on a 7.1 speaker layout using PLIIx, the sounds that were going to image behind you are extracted from the surround channels and sent to the speakers behind you. The leftover information remains in the speakers at your sides.


Now you can be sitting anywhere and sounds that were intended to come from behind you will always come from that direction. No magic involved, just an additional pair of surrounds behind you (makes it difficult for those sounds to come from any other direction).


Same directionality with greater imaging stability.
 

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Discussion Starter · #3 ·

Quote:
Originally Posted by sdurani  /t/1471364/how-does-5-1-encoded-video-sound-on-a-7-1-system#post_23280311


Not sure what you mean by "distortion", but...


If you were using only 2 surround speakers, placed along your sides and slightly behind you (±110-120°), some sounds would image at your sides while other sounds would phantom image in between (appear to be coming from behind you).


Of course, you have to be sitting in the sweet spot to hear this directionality. If you're sitting left or right of centre, then the sounds you were hearing behind you will collapse6 to the nearest surround speaker.


When you play back a 5.1 soundtrack on a 7.1 speaker layout using PLIIx, the sounds that were going to image behind you are extracted from the surround channels and sent to the speakers behind you. The leftover information remains in the speakers at your sides.


Now you can be sitting anywhere and sounds that were intended to come from behind you will always come from that direction. No magic involved, just an additional pair of surrounds behind you (makes it difficult for those sounds to come from any other direction).


Same directionality with greater imaging stability.

I'm not quite sure you answered my question. I'm familiar with how a set up 7.1 system would look like I'm not an idiot lol but I was wondering how accurate the 7.1 codec worked with 5.1 track. From what I understand dolby would take the rear channels and would try it's best to split the sound from the 2 rear channels in to 4 if I'm not mistaken correct me if I'm wrong. Now since it's not encoded to have 4 surrounds only 2 I was wondering if it sounds off or it doesn't sound quite right at points in time or if there were ever moments when watching movies that have intense surround effects intended for 2 channels that sounds wrong with 4. If anyone has any infirmation that'd be great. If price was not an issue would a 7.1 be better or even 9.2 or 11.2.


My only concern is that if you hear a helicopter behind you moving from left to right encoded in 5.1 and then played on a 7.1 would be that it might sound strange figuring that dolby had to guess how it sounds with 4 rear speakers as opossed to 2.
 

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Look at the last part of Sanjay's response - sounds that image behind you in 5.1 get anchored in speakers in 7.1. It works the same way that PLII takes dialog that phantom images to the center in a stereo source and anchors it in the center speaker.
 

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IMO while watching blu-ray movies I can't tell if its 5.1 DTS HD MA OR 7.1 DTS HD MA. PLIIx does an excellent job at taking 2 ch stereo or 5.1 and making it 7.1. IMO 7.1 sounds better than 5.1 even if the source is 5.1. The sounds and effects don't sound odd it sounds like that was the way it was made.


But yeah Sanjay did answer your question.
 

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Quote:
Originally Posted by ComputerTech0903  /t/1471364/how-does-5-1-encoded-video-sound-on-a-7-1-system#post_23283228


My only concern is that if you hear a helicopter behind you moving from left to right encoded in 5.1 and then played on a 7.1 would be that it might sound strange figuring that dolby had to guess how it sounds with 4 rear speakers as opossed to 2.

If sounds are simple panning like what you just described, the ProLogic IIx algorithm (the thing that makes 5.1 into 7.1 by going from two surrounds to four) should handle it just fine. Heck, they do a decent job with stereo to 5.1 using ProLogic II, and that's way more complicated than going from 5.1 to 7.1. It's not that difficult a process for a company that specializes in this exact thing.
 

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Quote:
Originally Posted by ComputerTech0903  /t/1471364/how-does-5-1-encoded-video-sound-on-a-7-1-system#post_23283228


From what I understand dolby would take the rear channels and would try it's best to split the sound from the 2 rear channels in to 4 if I'm not mistaken correct me if I'm wrong.
Yes. And it doesn't just "try". Or "guess".
 

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Discussion Starter · #8 ·

Quote:
Originally Posted by sivadselim  /t/1471364/how-does-5-1-encoded-video-sound-on-a-7-1-system#post_23285411


Yes. And it doesn't just "try". Or "guess".

What is up with the pretentious avs forum member. Was it really necessary to give a little jab. I think sometimes people mainly post on avs forum because it gives them a chance to be rude to people without doing it to people's faces and their unhappiness with their lives disappears a little bit when they mean to someone else.


And don't give any crap about not meaning anything by it because that is one of the last ways someone would phrase a response to my question if they were only trying to be helpful as opossed to being a jerk.
 

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Quote:
Originally Posted by ComputerTech0903  /t/1471364/how-does-5-1-encoded-video-sound-on-a-7-1-system#post_23285910


What is up with the pretentious avs forum member. Was it really necessary to give a little jab. I think sometimes people mainly post on avs forum because it gives them a chance to be rude to people without doing it to people's faces and their unhappiness with their lives disappears a little bit when they mean to someone else.


And don't give any crap about not meaning anything by it because that is one of the last ways someone would phrase a response to my question if they were only trying to be helpful as opossed to being a jerk.

Honestly, I could understand if you called me a smartass, but how was my response "pretentious"?


It wasn't a jab. Maybe I should have elaborated. My point was that there is a lot more to it than just simply "trying" or "guessing". YOU specifically used those words for a reason, with a particular implication, right?
 

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Quote:
Originally Posted by ComputerTech0903  /t/1471364/how-does-5-1-encoded-video-sound-on-a-7-1-system#post_23283228


I'm not quite sure you answered my question. I'm familiar with how a set up 7.1 system would look like I'm not an idiot lol but I was wondering how accurate the 7.1 codec worked with 5.1 track. From what I understand dolby would take the rear channels and would try it's best to split the sound from the 2 rear channels in to 4 if I'm not mistaken correct me if I'm wrong. Now since it's not encoded to have 4 surrounds only 2 I was wondering if it sounds off or it doesn't sound quite right at points in time or if there were ever moments when watching movies that have intense surround effects intended for 2 channels that sounds wrong with 4. If anyone has any infirmation that'd be great. If price was not an issue would a 7.1 be better or even 9.2 or 11.2.


My only concern is that if you hear a helicopter behind you moving from left to right encoded in 5.1 and then played on a 7.1 would be that it might sound strange figuring that dolby had to guess how it sounds with 4 rear speakers as opossed to 2.

I went from 5.1 and added 2 back speakers to 7.1 and movies are even better regarding surround sound/effects. That is for both 5.1 (using PLIIx) and 7.1. Some folks have experienced that it doesn't make much of a difference, but I noticed a significant improvement. It doesn't sound unnatural at all, IMHO but more encompassing and better.
 
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