Difference between 2.0 using surround decode, 5.1 with EXTD surround and 7.1? - AVS Forum
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post #1 of 25 Old 06-19-2013, 06:29 AM - Thread Starter
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Hello,

I haven't been able to find a good comparison or explanation of the differences between these different surround sound methods:


  • 2.0 with surround decode set to PLIIx
  • 5.1 with EXTD Surround set to PLIIx
  • 7.1 straight


If it matters, I am using a Yamaha RX-V673.

For the most part, I am looking for a surround experience, even if the original content is only in 2.0. I know that for my receiver if I specify on my source that I have 7.1 speakers, I will only have silence in my rear speakers unless I am playing true 7.1 content. Because of this, I've opted to use 5.1 with EXTD Surround, since that seems to be the most efficient way without having to change my speaker setup every time.

I'd love if anyone could explain the differences/pros/cons of the above options. Am I doing the best thing by telling my source that I only have 5 speakers, then using the receiver to process the extra sound data to the rear?
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post #2 of 25 Old 06-19-2013, 07:24 AM
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Quote:
Originally Posted by WeApOn View Post

Hello,

I haven't been able to find a good comparison or explanation of the differences between these different surround sound methods:


  • 2.0 with surround decode set to PLIIx
  • 5.1 with EXTD Surround set to PLIIx
  • 7.1 straight


If it matters, I am using a Yamaha RX-V673.

For the most part, I am looking for a surround experience, even if the original content is only in 2.0. I know that for my receiver if I specify on my source that I have 7.1 speakers, I will only have silence in my rear speakers unless I am playing true 7.1 content. Because of this, I've opted to use 5.1 with EXTD Surround, since that seems to be the most efficient way without having to change my speaker setup every time.

I'd love if anyone could explain the differences/pros/cons of the above options. Am I doing the best thing by telling my source that I only have 5 speakers, then using the receiver to process the extra sound data to the rear?

7.1 plays all seven channelsw exactly as mixed and mastered for the media you are playing. 5.1 with PLIIX would not be completely accurate in recreating a 7.1 soundtrack. The source would fold the rear surround sounds into the side surrounds, then the receiver's processor would invent the rear surrounds based on its own algorithm, unlikely to exactly duplicate the original mix.

Setting the device to output stereo creates the same problems, only more so. For 5.1 or 7.1 content the center and surrounds are folded into the 2.0 mix and can never be "recovered" as they were mixed. Instead you'll get whatever the PLIIX logic feels like sending to center and surrounds. It will surely differ from the "real" mix.
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post #3 of 25 Old 06-19-2013, 07:34 AM - Thread Starter
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Gotcha. Thanks! Pretty much just what I was expecting, in a more technical way.

What do most people do? Is it really worth switching over to 7.1 each time you use a true 7.1 piece of media? And then back to 5.1 or 2.0 with PLIIx so that the extra speakers aren't rendered useless?
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post #4 of 25 Old 06-19-2013, 09:04 AM
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I don't have 7.1, but I'd be quite surprised if there isn't a setting in PLII that expands things to 7.1. So just like "normal" PLII, it won't try to expand a native 7.1 track to 7.1 but simply will pass it through unaltered.
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post #5 of 25 Old 06-19-2013, 10:13 AM
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Most processors allow you to set surround modes based on the type of input. So, there's no switching required by the end user. You tell the AVR what you want it to do when the source is stereo, 5.1, and 7.1. Once set up, the receiver handles everything from there. And, yes, DSPs like PLIIx.and DTS Neo:6 do nothing when the source is already 7.1.
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post #6 of 25 Old 06-19-2013, 10:38 AM - Thread Starter
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Quote:
Originally Posted by JHAz View Post

I don't have 7.1, but I'd be quite surprised if there isn't a setting in PLII that expands things to 7.1. So just like "normal" PLII, it won't try to expand a native 7.1 track to 7.1 but simply will pass it through unaltered.

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Originally Posted by BIslander View Post

...yes, DSPs like PLIIx.and DTS Neo:6 do nothing when the source is already 7.1.

Unfortunately, from what I've heard about how my receiver works with my PS3 and PC.. If I tell my PS3 or PC that I have 7 speakers, there is no way to engage PLII or PLIIx -- thus the two rear speakers will be silent unless it is true 7.1 content.

Ideally I'd like to tell my PS3 and PC that I have 7 speakers, and when content is NOT in 7.1, it knows how to handle it. Unless I misunderstood something along the way, I would need to change my PS3/PC settings each time I use a true 7.1 form of media, and then back to 5.1 when it is only a 5.1 mix, otherwise I would experience the silence.

If I am wrong(and I would love to be), I might need some help on figuring out how to set that up properly.

Yamaha RX-V673 if I didn't mention it above.

Thanks!
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post #7 of 25 Old 06-19-2013, 10:47 AM
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The PS3 should not be an issue. Like most playback devices, I believe it can be set to output the correct number of channels so that stereo goes out as stereo and so on. Telling it you have seven speakers means it will not downmix 7.1 content to fewer channels. But, it should not expand stereo or 5.1 to 7.1, leaving that function for your receiver. (I don't own a PS3 and cannot help with the settings, tho.)
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post #8 of 25 Old 06-19-2013, 11:21 AM - Thread Starter
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Originally Posted by BIslander View Post

The PS3 should not be an issue. Like most playback devices, I believe it can be set to output the correct number of channels so that stereo goes out as stereo and so on. Telling it you have seven speakers means it will not downmix 7.1 content to fewer channels. But, it should not expand stereo or 5.1 to 7.1, leaving that function for your receiver. (I don't own a PS3 and cannot help with the settings, tho.)

I will test this tonight. Maybe I am thinking of a restriction of my older receiver, a Yamaha RX-V661. It was from 2006. I remember being told that I would need to change between 5.1 and 7.1 on my PS3 each time because my Yamaha receiver would see the source as 7.1 and it didn't support PLIIx if the source was 7.1

I will test this tonight on the new receiver.

If anyone has experience with this or with a PC, would love to hear.
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post #9 of 25 Old 06-19-2013, 11:33 AM
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On a PC, it depends on what player software you use. Some players (like VLC) use exactly the number of channels you've configured in the "Playback Devices" Sound Configure menu, with the surround channels present but silent when playing a stereo source. Others will output only the number of channels provided in the source material. Sorry: I seldom use my computer's HDMI output for listening to music, so I can't recommend any particular player. You should be able to get appropriate advice in the HTPC forum http://www.avsforum.com/f/26/home-theater-computers

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post #10 of 25 Old 06-19-2013, 05:04 PM - Thread Starter
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Just did some testing with PC games, which allowed me to move around in an environment and 'force' where the sound was coming from. To recap, I am trying to see if I need to switch between specifying 7.1 and 5.1 on my source(PC or PS3) when switching between true 7.1 content, and 5.1 content that I was upmixed to 7.1. My initial reasoning behind thinking that I needed to switch between the two was because I was told that the 5.1 data would not properly be upmixed to 7.1 if the source says I have 7 speakers to begin with. Basically -- it would be outputting silence in the extra 2 speakers and block the PLIIx from taking place.

(With my PC set to 7.1 speakers, and my Yamaha set to Straight -- with PLIIxMovie for EXTD Surround):
  • Tested Left 4 Dead 2, which supports 7.1. I set 7.1 in the options and I was getting silence from my side speakers. If I changed the DSP to 7ch Stereo or Spectacle or pretty much anything else, it worked.
    -Why was 7.1 STRAIGHT not working properly?
  • Tested Hitman Absolution, didn't state if it supported 7.1 or not, but all 7.1 channels were working and sounded as they should.
  • Tested Metro: Last Light. Also unsure if it is 5.1 or 7.1 natively, but it worked perfectly. All 7 channels output properly.

(With my PC set to 5.1 speakers, and my Yamaha set to Straight -- with PLIIxMovie for EXTD Surround):
  • Tested Left 4 Dead 2 again. Regardless of if I set 5.1 or 7.1 in the options, I was now hearing proper audio from the side channels.
    -For a game that has an option for 7.1, why can I only use my side speakers if I set my PC to 5.1 and then run PLIIx on my receiver?

Overall, I would assume that the other two games did not natively support 7.1, and it seems to have disproved my original concern. Again, this was something told to me a long time ago and I have always thought I needed to treat the source channels as such. The only question here is why a true 7.1 source was not working when I had told Windows I have 7 speakers on the receiving end. Any ideas?

Going to do some testing with the PS3 now. I will post back with my results.

This might have moved outside the realm of receivers. If so, let me know and I will try to find a relevant sub-forum to post in.
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post #11 of 25 Old 06-19-2013, 05:19 PM - Thread Starter
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PS3 Testing:

(For this test I told my PS3 in the Audio Settings that I have 7 speakers, which was previously set to 2. I was also using STRAIGHT and PLIIxMovie.)
  • Tested The Last of Us -- unknown if it is a 7.1 or 5.1 game, but all channels were working perfectly.
  • Tested Game of Thrones Season 1 Blu-Ray. I am quite sure this is only a 5.1 title. All 7 channels working properly.

Looks like no problems with the PS3 set to 7.1.

I'm thinking the limitation I was originally told about may have been for my old receiver. Everything here seems to be working properly.
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post #12 of 25 Old 06-19-2013, 05:38 PM
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WeApOn - Your posts seem to describe 5.1 using the rear speakers and 7.1 adding the sides. That's backwards. A 5.1 system has surrounds, which should be placed on the side walls, and 7.1 adds the rears. How do you have your speakers attached?
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post #13 of 25 Old 06-19-2013, 06:11 PM - Thread Starter
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Quote:
Originally Posted by BIslander View Post

WeApOn - Your posts seem to describe 5.1 using the rear speakers and 7.1 adding the sides. That's backwards. A 5.1 system has surrounds, which should be placed on the side walls, and 7.1 adds the rears. How do you have your speakers attached?

I have the two speakers on my REAR wall, behind me, plugged into "Surround Back/Bi-amp". That is correct, no?

It seems like in most cases for me, when 5.1 is working and 7.1 is not working -- the sides are muted, not the rears. Could this be content specific?

Edit: Also, I always thought 5.1 could mean two speakers behind OR two speakers on the side. I didn't think there was a specific classification? Do you mean specifically when 5.1 is compared to 7.1?
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post #14 of 25 Old 06-19-2013, 06:27 PM
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Connecting the rears speakers to the Surround Back terminals is correct.

While you can put your speakers wherever you want, in a 7.1 system, source material that is 5.1 will have active surrounds and silent rears. If the surround content were flagged for rear speakers, then people with 5.1 systems would never hear the surround content because they don't have rear speakers configured in their systems. That's why it is surprising to see your posts describing playback scenarios where the rears are active and the surrounds are silent.
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post #15 of 25 Old 06-19-2013, 06:35 PM - Thread Starter
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Originally Posted by BIslander View Post

Connecting the rears speakers to the Surround Back terminals is correct.

While you can put your speakers wherever you want, in a 7.1 system, source material that is 5.1 will have active surrounds and silent rears. If the surround content were flagged for rear speakers, then people with 5.1 systems would never hear the surround content because they don't have rear speakers configured in their systems. That's why it is surprising to see your posts describing playback scenarios where the rears are active and the surrounds are silent.

Gotcha. Fully understood.

I'm going to go back and try the 5.1 tests and turn OFF EXTD Surround. From what you're saying -- I should hear 5 channels, my rears should be silent.

As for the one case where the sides were silent, I'm really unsure. Even the options menu had support for 7.1 and it was silent. I'm thinking it's something software related to that particular game.
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post #16 of 25 Old 06-19-2013, 06:49 PM - Thread Starter
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I retested the two PC games that worked in 7.1 before, and with EXTD Surround set to OFF, I still heard all 7 channels. This must mean that the content is natively 7.1? I need to find something that is definitely in 5.1 and test that.

I then tested the Blu-Ray again and it performed just like you said with EXTD Surround set to OFF -- no rears, only sides.

It just seems on PC there are some oddities that are hard to figure out -- whether it be the receiver, content, windows settings, there's alot of complexity... I just want to set my speakers to 7.1 and be able to get the most of all of them.
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post #17 of 25 Old 06-21-2013, 05:31 PM - Thread Starter
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Just found one example that proves my initial worry to be true --- If I have my computer speakers set to 7.1, certain applications will not be in 7.1, and PLIIx will not work in upmixing the 5.1 to 7.1

EIther due to the program sending silent data to the two extra channels, or some other reason... The only fix is to change my PC settings to 5.1 and keep PLIIx, then it works.

I tested with a game that output 5 channels when I told Windows I had 7. From what it seems, it was sending silent data to the other two channels, so my PLIIx would never kick in.

My original intention was to avoid having to switch between telling Windows that I have 7 speakers(when I use native 7.1 content) or that I have 5 speakers(when the above example happens, causing two silent channels).

Unless anyone else has an idea, I think the only solution will be to keep Windows set at 5.1 and apply PLIIx. The downside of this will be that true 7.1 content will end up being 5.1 --> PLIIx upmixed to 7.1. I'm not sure how negative this is, as I don't know the technical facts behind the differences.

Unfortunately it doesn't seem like I have any other options, as one program to another this will differ, but the only way to maintain 7 channel output ALL THE TIME is to force 5.1 and PLIIx.

Can anyone shed some light on the detrimental effects of using 5.1 & PLIIx for true 7.1 content, versus using native 7.1?
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post #18 of 25 Old 06-21-2013, 06:38 PM
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First off, your receiver will tell you whether the incoming PCM content from the PC is 5.1 or 7.1. So, there's no need to guess about that. If you play a source that you know is 5.1 and the AVR reports getting 7.1 with the two back speakers silent, you'll know what the PC is doing.

Some genuine 7.1 content will have specific effects that will probably sound better in 7.1 than 5.1 expanded using something like PLIIx. With other 7.1 sources, it probably won't matter. I can't imagine that there's all that much native 7.1 content that you'll be playing on your PC. It would seem that setting the output to 5.1 will work most of the time and an occasional change to 7.1 doesn't seem like a big inconvenience. But, only you can decide how much that matters to you.
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post #19 of 25 Old 06-21-2013, 06:43 PM - Thread Starter
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Quote:
Originally Posted by BIslander View Post

First off, your receiver will tell you whether the incoming PCM content from the PC is 5.1 or 7.1. So, there's no need to guess about that. If you play a source that you know is 5.1 and the AVR reports getting 7.1 with the two back speakers silent, you'll know what the PC is doing.

Where can I tell this on my receiver? If you mean the OSD that actually shows the speakers -- if I tell Windows that I have 7 speakers, the output on my receiver will always show 7 speakers, regardless of what the content is. Unless there is another way to tell what type of audio the receiver is getting? I've never seen anything other than that.
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Some genuine 7.1 content will have specific effects that will probably sound better in 7.1 than 5.1 expanded using something like PLIIx. With other 7.1 sources, it probably won't matter. I can't imagine that there's all that much native 7.1 content that you'll be playing on your PC. It would seem that setting the output to 5.1 will work most of the time and an occasional change to 7.1 doesn't seem like a big inconvenience. But, only you can decide how much that matters to you.

I agree. I doubt there will be much native 7.1 content that I will be experiencing on my PC, so the 5.1 & PLIIx to guarantee 7 speaker output all the time is probably my best option.
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post #20 of 25 Old 06-21-2013, 06:50 PM
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I was referring to the AVR display. If it shows the signal arriving from your PC is 7.1 no matter what the source, then you are stuck.
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post #21 of 25 Old 06-24-2013, 06:39 AM - Thread Starter
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I was referring to the AVR display. If it shows the signal arriving from your PC is 7.1 no matter what the source, then you are stuck.

Yes. Regardless of the content playing on my PC, it shows 7 speakers displayed. Unless there is something else on the OSD that shows the signal information. If not, it will always show 7 speakers as soon as I set that in Windows. Due to this, it seems like Windows is more in charge of what happens to my audio.
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Yes, if Windows takes something like a stereo source and sends all seven channels, with five of them silent, it is limiting your options in the AVR.
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post #23 of 25 Old 06-24-2013, 11:11 AM
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Even the simplest $99 BD player will transmit the correct number of channels. Why are you using source devices that are sending blank channels to your receiver? Is there any option on those source devices to transmit the signal in its native bitstream or are you stuck having to decode to PCM in the player?

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post #24 of 25 Old 06-24-2013, 11:44 AM - Thread Starter
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Even the simplest $99 BD player will transmit the correct number of channels. Why are you using source devices that are sending blank channels to your receiver? Is there any option on those source devices to transmit the signal in its native bitstream or are you stuck having to decode to PCM in the player?

I am using a PC running Windows 7. I'm unsure what is being seen on the receiver end, though I do see 7 speakers lit up all the time. It seems that I have some success with 5 channel sources being upmixed to 7, but a few occasions I believe the software itself is overriding that.

All in all, it's quite hard to trace what is controlling my sound. It seems to differ with each program.
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post #25 of 25 Old 06-24-2013, 11:59 AM
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Quote:
Originally Posted by WeApOn View Post

Quote:
Originally Posted by sdurani View Post

Even the simplest $99 BD player will transmit the correct number of channels. Why are you using source devices that are sending blank channels to your receiver? Is there any option on those source devices to transmit the signal in its native bitstream or are you stuck having to decode to PCM in the player?

I am using a PC running Windows 7. I'm unsure what is being seen on the receiver end, though I do see 7 speakers lit up all the time. It seems that I have some success with 5 channel sources being upmixed to 7, but a few occasions I believe the software itself is overriding that.

All in all, it's quite hard to trace what is controlling my sound. It seems to differ with each program.

It also will differ depending on what software player you use under Windows 7. Different player software handles the audio channels differently.

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