Bitstream vs PCM

Moonfly · 14-11-2009, 1:36 AM

The debate on which is best has raged for as long as HD formats, and Ive yet to see a definitive answer as to which is best or which should be used. Ive not been able to offer any explanation to that question myself either, until just now.

I noticed on my AVR that while using the PS3, which is restricted to PCM only, this seems to remove Audyssey from functioning. So my question is, can Audyssey be used with LPCM stream from sources or not, and if not (as it seems to me) doesnt this tip the balance in favour of using bitstream if your equipment is high end enough over your source.

As far as I can determine, this now seems to be the only thing separating the two methods. Any thoughts?

Max N · 14-11-2009, 5:09 AM

I use LPCM into my processor and Audyssey works fine. Maybe a problem with your processor, or a setting?

Welwynnick · 14-11-2009, 8:10 AM

LPCM is the lowest common denominator for all digital audio. LPCM is what DACs, ADCs, processors and convertors use. No processing is done with bitstream - it always has to be converted to PCM first, so there's no reason why an amp couldn't apply room correction to LPCM. Quite the opposite in fact; there are hardware reasons why it shouldn't work with bitstream.

Nick

Avi · 14-11-2009, 8:30 AM

Quote:

Originally Posted by Moonfly

So my question is, can Audyssey be used with LPCM stream from sources or not, and if not (as it seems to me) doesnt this tip the balance in favour of using bitstream if your equipment is high end enough over your source.

Yes Audyssey does/should work with L-PCM. Bitstream is encoded data so before any processing can be done with it it needs decoding. The product of the decode will be L-PCM.

Some processors (Marantz - can't recall the model) don't have the DSP capacity to decode bitstream and apply Audessey so in this case Audessey only works with L-PCM input.

If the signal is converted to multi-channel analogue in the player then usually this type of signal will bypass DSP including Audyssey processing in an AVR/pre pro (the external Audyssey processor performs ADC/DAC so does apply to analogue).

AVI

paulst10 · 14-11-2009, 9:08 AM

If you check the display of your Onkyo amp when sending LPCM, your Audyssey light should still be on, so I can only assume it's still being applied

Welwynnick · 14-11-2009, 9:31 AM

Quote:

Originally Posted by Moonfly

The debate on which is best has raged for as long as HD formats, and Ive yet to see a definitive answer as to which is best or which should be used. Ive not been able to offer any explanation to that question myself either, until just now.

You can probably answer that question for yourself. You have an Onkyo TX-SR875 - have you tried using a bitstreaming player with it?

Nick

Avi · 14-11-2009, 9:59 AM

Quote:

Originally Posted by welwynnick

You can probably answer that question for yourself. You have an Onkyo TX-SR875 - have you tried using a bitstreaming player with it?

Nick

I guess a word of caution if making a comparison like this is to ensure that any difference in output level is calibrated out. If bitstream caused the AVR to produce a higher output level realtive to L-PCM it may subjectively sound better for this reason alone.

AVI

Moonfly · 14-11-2009, 2:35 PM

Quote:

Originally Posted by paulst10

If you check the display of your Onkyo amp when sending LPCM, your Audyssey light should still be on, so I can only assume it's still being applied

Thats what has promoted my confusion, I was playing a cd the other day on the PS3 and the light was off. Is the amp clever enough to know the difference between music and movies, and only apply Audyssey to the films?

Quote:

Originally Posted by welwynnick

You can probably answer that question for yourself. You have an Onkyo TX-SR875 - have you tried using a bitstreaming player with it?

Nick

Te only thing that would work would be my 360 or a DVD player I have, neither of which are capable of HD audio.

Welwynnick · 14-11-2009, 3:16 PM

Quote:

Originally Posted by Moonfly

Te only thing that would work would be my 360 or a DVD player I have, neither of which are capable of HD audio.

I can tell you what the answer is, but you will only believe me when you hear it for yourself.

Nick

paulst10 · 14-11-2009, 3:45 PM

Quote:

Originally Posted by Moonfly

Thats what has promoted my confusion, I was playing a cd the other day on the PS3 and the light was off. Is the amp clever enough to know the difference between music and movies, and only apply Audyssey to the films?

Te only thing that would work would be my 360 or a DVD player I have, neither of which are capable of HD audio.

Did you have the Onkyo in pure audio mode or direct mode by any chance ?

It will apply Audyssey to all the surround modes - Pro-logic, Neo:6, Stereo, Mono, THX etc! etc! but switches Audyssey off for pure audio & direct

Moonfly · 14-11-2009, 5:17 PM

Quote:

Originally Posted by welwynnick

I can tell you what the answer is, but you will only believe me when you hear it for yourself.

Nick

Thanks for that

Quote:

Originally Posted by paulst10

Did you have the Onkyo in pure audio mode or direct mode by any chance ?

It will apply Audyssey to all the surround modes - Pro-logic, Neo:6, Stereo, Mono, THX etc! etc! but switches Audyssey off for pure audio & direct

Nope, no audio modes. When playing from the PS3 most sound modes are unavailable for selection. It was just displaying multi PCM.

namuk · 14-11-2009, 5:36 PM

Get a PS3 Slim