Player decoding or Receiver decoding, that is the question

[welwynnick]

Of course I've been itching to dive back into this debate for some time, but first I want to go back to this excellent post by EWL5 about amplifier decoding (which I've paraphrased). I whizzed through it first time, but only read it thoroughly yesterday, and something leapt out at me:

Originally Posted by EWL5

This question ranks right up there with "Which BD player should I get?" and "Can I hear the new lossless audio using my current receiver?" ......

On a purely theoretical basis, the decoding done in the player should be identical to the decoding done in the AVR/prepro.......

Shouldn't they sound the same given the fact that decoding is just a simple unwrapping of PCM from the original codec? Yes and No and here's why:

Yes, decoding will sound the same
When the following conditions are met

1) The crossover in the BD player is the same as the one in the AVR/prepro

2) Delay/Level settings for each speaker channel approximate the settings arrived at when calibrating for the AVR/prepro

3) For analog out, it is possible for the LFE to be boosted by +15dB in the downstream amp whenever speaker settings in the BD player are set to SMALL.

4) Identical DAC's used b/w the BD player and the AVR/prepro

5) ..when a player decodes and transmits the PCM via HDMI 1.1+ as the DAC's are used in the AVR/prepro....

No, decoding will not sound the same

1) Most BD players have a fixed crossover (~100-150Hz)... AVR/prepro's on the other hand, allow a multitude of crossover settings to best match your situation..... Analog users are at the mercy of the fixed crossover.

2) Most decent AVR/prepro's come with automatic calibration functions that attempt to correct for errant frequencies, nulls, etc. (examples include Audyssey, MCACC, etc.)....

3) Boosting of LFE is always appropriately handled when the AVR/prepro accepts the bitstream. If you are working with multichannel analog out connections, you better have the capability to boost that LFE by +15dB whenever any speakers are set to SMALL in the BD player.

4) DAC's play a large part in the final output. In most cases, AVR/prepro DAC's will be superior to a BD player's...

5) Some naysayers claim that jitter from PCM transmission over HDMI audibly affects the signal. Can be minimized or solved using technologies like Pioneer's PQLS or Denon's DenonLink.

Almost all the issues with amplifier decoding relate to D to A conversion, and not to bitstream to LPCM conversion. The exception is the final one, in bold. ELW5, if you think that any of the other nine issues apply to decompression, could you explain why, as I don't see it?

This leaves me with jitter as the explanation for the difference. There may be other issues, which have been discussed at AVS and AVF, but these seem to boil down to noise and interference on the LPCM signal from the player, and I would categorise those as jitter-like anyway.

There was some uncertainty expressed here about whether it was really as simple as that. That related to differences heard between the PS3 and stand-alone players when using a Pioneer SC-09TX receiver. That uses TI/BB SRC4192 sample rate convertors to buffer the digital audio stream. Similar SRCs in the SC-07 were shown to be very effective in jitter reduction, and it was presumed that the 09TX would perfrom at least as well. HiFi News tested both in the last few months, and found that the older but more expensive model actually had much higher jitter - 710ps vs 50ps, so this explianed why it would be sensitive to LPCM jitter from the PS3 in this example.

To reinforce this from my own point of view, I'm quite familiar with the effect of jitter on stereo replay. I've had two players and three amplifiers with i-link connections, and they all clean up music reproduction in ways that are very similar to amplifier decoding. The effects are familar and recognisable, and while there could be other explanations, I'm pretty convinced that it is indeed down to jitter.

Nick