Axiom Home Page Forums General Discussion Technical Questions Can sound quality differ between decoders?

I have been diving into the depths of the audio settings on my PS3 and my Pioneer SC-05. This was prompted by a recent thread where someone (Zimm maybe?) couldn't get their 3808 display to read DTS-HD or similar. I was experiencing the same issue with my SC-05 and PS3 combo. So after research I am now clear on always setting the PS3 to LPCM and letting it decode everything rather than the PS3 sending bitstream to my SC-05. So now to my question for you audio guru's out there:

Is there any benefit in terms of pure quality of sound (forget menu beeps and the like) to letting one device decode the audio vs. another? In other words can a modern AVR 'better' decode DTS-HD than the PS3 or any other BDP? Or is it simply a yes/no equation where the output of decoding is the same regardless of 'who' decodes it?

I could not find a definitive answer to this in my research so far, but there always seems to be an answer here!

Dan, the decoding should be technologically well-established enough that no significant difference would occur between different units.

You mentioned an "issue" about a receiver not displaying the HD formats. If you meant after the HD had been decoded to PCM by the player, then the receiver would have no way of knowing that it originally started out in one of the HD formats before being decoded, and of course couldn't show it on the display.

Thanks John.

The 'issue' I was having is exactly what you described, but at least that part I understood - when the AVR was receiving LPCM.

Where I was getting confused was when I set the PS3 to output bitstream and still was not getting the display on my AVR indicating an HD audio format even though it was chosen in the playback options on the disc itself. With some searching I learned that the PS3 does not output the HD audio formats over bitstream, just the standard Dolby Digital or DTS.

I did not know that about the PS3. So in this case, we should always have the PS3 set to LPCM and do all decoding via the PS3, right? To take advantage of the HD codec I mean.

Yes. And especially if you are using the 507 listed in you sig since it will not decode the HD formats.

The 507 does decode the new formats, while the 506 (last years model) does not. Then the big jump in codecs to the 607 is the theoretical ability to use 9.1 (2 extra speakers located above the L/R fronts), Pllz I think its called?

Golden, as Dewd said you should always set the PS3 to decode and send LPCM to your AVR if you want to hear any of the HD audio tracks. Here is one example of several threads I found that explain this. I still have been unable to find an official statement from Sony or Dolby or DTS stating this limitation though.

PLIIZ - the first review I have seen on this new technology can be found here using the Onkyo TX-SR607.

Thanks for the link Dan, an interesting read for PS3 owners.

DTS mentions the PS3's limitation as their first FAQ:
http://www.dts.com/Resources/FAQs.aspx

It came about, because the PS3's HDMI chip is more like a 1.2.5 rather than 1.3. The PS3 went into production before the HDMI 1.3 spec was finalized; the chip used was a modified 1.2 to add some, but not all of the 1.3 features. The missing one is obviously the ability to bitsteam HD codecs.

Thanks for the explanation and link Chris. I used the search function on the DTS website and that FAQ did not turn up as a hit.

So it is true that it will take a hardware change in future PS3 models to enable this feature. I wonder if Sony would bother doing this?

Yes, it would require Sony to use a different chip. They've already made at least 3 or 4 different hardware revisions of the PS3, but never changed out the HDMI chip. So I doubt they'll do it until they make a "PS three", like the smaller/thinner versions of the PS1 and PS2, which sometimes gained new features (like progressive scan DVD playback).

While I have a receiver which supports the decoding the the HD audio formats, I don't see a reason to do it that way. There is more than enough bandwidth on the HDMI cable, and if the player is doing the decoding then it can provide features like mixing in secondary audio (for things like commentary or interactive features). With bitsteaming that's not possible, and the secondary audio is unheard.

A decoder which passes the Dolby/DTS certification for the lossless formats will produce exactly the same output as any other properly functioning decoder. It doesn't matter if it's done in the player or in the receiver.

The one "benefit" enthusiasts always bring up, is if the receiver knows that it is a DTS-HD MA track with 5.1 channels and you've asked for 7.1 dematrixing, it will apply NEO:6 instead of Dolby ProLogic IIx. Know what? I like the sound field created by PL IIx more than NEO:6, and by sending LPCM to my receiver I can choose which algorithm to apply (conversely I can use NEO:6 with Dolby TrueHD, if I so wanted).

Bitsteaming gains nothing over decoding to LPCM, and actually loses some features or flexibility.

You are saying that Neo6 dematrixing can't be applied to a 7.1 PCM signal? (I'm not in front of my system so can't test this right now)

So other than the above question, the only benefit is to see your receiver light up with the HD audio format of choice?

Funny, cuz that's partly what triggered starting this thread in the 1st place!

No, Neo:6 can't be applied to a 7.1 PCM, because it's already using all 7 channels.

But Neo:6 -or- PL IIx can be applied to a 5.1 PCM. Where as some receivers limit the user to applying PL to Dolby bitsteams and Neo to DTS.

Yeah, all the bitsteam gets you is a light.

Oops, I meant 5.1 PCM - typo!

You know, this is great information and is something that I bet most people don't consider when shopping for AVR's. You don't need to pay for HD audio processing depending on where you decode.

Thanks! I have learned my something new for today - except it took me a few days to get there!

I did not know that. Thanks.