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AVR questions/help

post #1 of 4
Thread Starter 
(Note: turned out longer than expected, TLDR at bottom)


Firstly, I should say I'm a complete noob in this department and I'm sorry if any of my questions are basic/stupid. Also sorry if this is in the wrong place.

I bought my first AV receiver about a week ago and after setting it up and playing around with it I have a few questions I hope you guys can help with. I've tried googling around but it's just leaving me more confused.

The system in question is the LG SR906 (http://www.lg.com/uk/home-entertainment/lg-SR906SB-home-cinema-system), I have my PC (HD7870) and PS3(slim) connected via HDMI to the receiver and the receiver to a BenQ EW2430 (http://www.benq.com/product/monitor/ew2430/).

1. Regarding the games on PS3.
As I understand it PCM mode on the receiver is the best option as it provides lossless audio? My problem is, certain games won't output 5.1 audio unless I mess with the options and get it to output in either DD or DTS.

So I am wondering if I should just change the settings to force DD/DTS 5.1 on games that won't output 5.1PCM and change the settings back when I want to play a game that does support 5.1pcm. Is the difference in sound quality THAT huge? As I haven't really noticed it (but I'm also wondering if that is due to incorrect set up). What I mean by this is in games that support both options, the surround sound seems to work, like if I spin around the audio moves around the speakers, I'm just not sure of a difference in quality. Or should I just play all my games in DD/DTS

2. Regarding BluRays on PS3.
This relates to the gaming issue slightly. If I have my PS3 configured to output PCM 5.1 as well as DD/DTS 5.1, then in movies I have the option for both depending on wether I set Bitstream or LPCM, so I am wondering is this just the same as the solution above, switch the settings as necessary since LPCM is superior.

Also, something that slightly confuses me here is none of my BluRays say they support LPCM 5.1 or anything, it only says things like DTS, DTS-HD on the back of the case, does this mean they actually do not, and playing the movies with LPCM is irrelevant? Or is LPCM allowing my receiver to play the DTS-HD audio instead of regular DTS?

3. Playing DVD's on PC

When playing DVD's on my PC I can't notice a difference in audio quality between PCM and DD, PCM just seems louder. I'm assuming this is because there is no HD audio track on a dvd and a HD audio track is where PCM outshines DD? Please correct me if this is wrong.

4. Playing downloaded movies on PC/VLC media player

When playing a file (e.g. .mkv) on VLC when I go to Audio > Audio Device I have the choice of selecting 5.1 or a/52 over S/PDIF. When selecting the latter audio will output in DD or DTS 5.1 depending on the file. When I select 5.1 the audio comes out as 5.1 PCM. However the PCM sounds a fair bit worse, it's much louder and the vocals are not as clean, almost sounding distorted.

What confuses me is everything is connected by HDMI, so why is it offering a optical option, and why does that output DD/DTS. What REALLY confuses me is why the PCM sounds alot worse.

5. Gaming on PC

When playing games on PC, no matter what I do the only option available is PCM, I haven't been able to find a way to force DD or DTS 5.1. This seems to leave me at the mercy of each specific game as to wether I can get any 5.1 sound at all. Games with no setting in the options menu to adjust the speaker set up will leave me with only stereo audio, games that do have the setting allows me to get 5.1. For example, Counter Strike: GO allows me to set 5.1 as does StarCraft 2, Bioshock Infinite and Remember Me have no such options and only allow me 2.1 or 2.0 audio even though my receiver will show PCM with all of the speaker options lit up. I'm at a loss for a solution here so hopefully you guys can provide some insight.

Thank you for taking the time to read and I really appreciate any information you guys can prodive on my issues.


Taking into account my set up/ receiver:
1 PCM or DD/DTS when gaming on PS3?
2 Bitstream or LPCM when watching BluRays on PS3?
3 No difference between PCM and DD/DTS when watching DVDs on PC?
4 .mkv audio sounds worse through PCM than DD/DTS on PC/VLC media player.
5 Certain PC games only output 2.1 audio, never allow DD/DTS or 5.1.
post #2 of 4
Here's the thing about PCM and the other codecs:

PCM is the basic digital audio format used in home entertainment systems. PCM is how music and movies are mastered and PCM is the format that receivers are engineered to process in order to produce sound. A multichannel PCM soundtrack is quite large - too large to fit on a movie film strip or DVD. So, companies such as Dolby and DTS developed data compression codecs to save space. A large PCM track is fed into the encoder, where it is compressed to reduce the size. On playback, the decoder decompresses the track back into PCM. The old lossy codecs (DD 5.1 and DTS) compress the track so much that some of the original data cannot be restored. The new lossless codecs (TrueHD and dts-MA) use less compression and those decoders can restore everything that was removed by the encoders.

So, for questions 2 and 3, it doesn't matter whether you set your PS3 to bitstream or PCM when watching any sort of movie - BD or DVD. You will get the same PCM either way. All that changes is the device doing the decoding.

If a game will only output 5.1 when the player is set to DD 5.1 or DTS, then that's what you should use.
Edited by BIslander - 6/17/13 at 8:13am
post #3 of 4
Thread Starter 
Thanks for the info. So since my receiver can only decode DD and DTS, in order to decode other codecs I should set it to LPCM to have the PS3 do the decoding. Like, if I have a BluRay that has a lossless codec, this will allow the use of that codec. Am I understanding this correctly?

As for gaming my biggest issue is I can't get 5.1 on certain games since I can't force DD or DTS. I'm referring to PC gaming here, but thanks for the clarity on PS3 gaming, I realise now it was a bit of silly question as obviously if DD/DTS is the only way to get 5.1 then that is what I should use, I guess I was just looking for clarity.
post #4 of 4
You seem to have figured this out. smile.gif

Since your receiver lacks lossless decoders, you should set the PS3 to PCM so that it does the decoding. That gives you the best sound with Blu-rays.

If there's no way to send DD 5.1 or DTS from PC games, then you can apply PLII in your receiver to expand stereo to 5.1. PLII has a game mode you can try.
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