Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Why decode in the player?

Specific question relating to DD 5.1 and DTS 5.1 tracks with a 598/G9x/800 player into a Meridian G68 or 861 processor.

Any differences in sound quality:

1) Decoding in the player, transferring multichannel digital, upsampling in processor.

2) Transferring bitstream, decoding and upsampling in the processor.

I suspect not much difference at all - in fact, DD and DTS bitstreams from any of my DVDs players (598, Sony DVP-S7700, Philips 963SA) have sounded great decoded in my G68....

As far as I remember, decoding in the player is not so much a sound quality issue but allows the processor more free computing power to do other things like upsampling etc.

I think that may be true with the 568.2MM, but I believe the G68 and 861v4 have enough MIPs to do both. In fact, multichannel upsampling is inherent to the design of the G68 and 861v4.

It's an architectural issue.

You have a distributed architecture in the 568.2MM/G68/861. There's a DSP on the digital receiver, and it can either decode or upsample, it can't do both. So if it receives a bitstream it decodes from DD/DTS/MPEG, if it receives PCM 48K or lower, it upsamples.

Then the DSP on the digital receiver passes on to the DSP core.

Regards,

Just out of interest, is there a comparison of the horsepower inisde say an 800/861 to a modern PC? Given the fact that you can buy soundcards and even xbox's which can ENcode on the fly. How much power is really required to decode it?

Obviously there is a alot more going on inside the black box eg. MRC

JK. Are the G68 and 861 really not capable of decoding and upsampling multichannel bitstreams? The DSP cores of the G68/861v4 are considerably more capable than that of the 568.2MM (although I concede a lot of the MIPs are taken up with MRC).

I thought that, with the G68 at least, you either run a downsampled system (with 18-bit DSP speakers or if you choose to turn HS off) or an upsampled one with 96/24 DSP speakers. Hmm.

Decoding in the player is going to give a potential sound quality hit then if passing PCM as you have to contend with jitter? Whereas DTS/DD bitstreams are pretty much immune so it would be better to pass the bitstream for processing?

Mark

According to this 861 Data Sheet :

http://www.Meridian-audio.com/data/861v4_data_scr.pdf

Dolby Digital coming in from 598/800 digital outputs are upsampled to 24/96. It doesnt specifically mention dts but I would presume the same ?

~M~

AFAIK, DTS is not upsampled??

Nick - The G68 and 861v4 do not differentiate between DD and DTS when it comes to upsampling. The decoder applies the correct algorithm for DD or DTS and the upsampler converts the decoded 48kHz PCM to 96kHz. The upsampler has no knowledge of the original format of the source, only the number of channels. It just "sees" the PCM.

Manus - I think that data sheet confirms what we do know, that multichannel PCM will be upsampled. However, for me, the question as to what happens with raw DD and DTS bitstreams remains open.

I'll take a look tonight as my 598 just got back from Mother with a new comms board.

I guess the point I was alluding to is that if the latest processors can decode and upsample multichannel bitstreams, if you're not interested in DVD-A, then (all other things being equal) a 596 should do as well as a 598.

As far as I remember reading, the 598 decodes DD and DTS and converts it to multichannel PCM 24 bit. The 568.2mm via smartlink only then takes each channel and upsamples it from 48k to 96k. 2 channel PCM input only via SPDIF is also upsampled in all channels in the 568.2. DD and DTS via SPDIF is not converted to 24bit, 96k in the 568.2. I find the difference quite noticable. Upsampled movie sound is noticably better. More dynamic, smoother and more natural sounding. More depth of image. Especially DTS upsampled. WOW! Using the SPDIF input still sounds very good...your not losing a lot but it does sound noticably better via smartlink in my system when watching movies. But remember its movies so I probably wouldn't miss it a whole lot if my 598 died. My 596 would be just fine and CD's will be just as good.

Ron

Meridian uses Motoroal 56367 chips. (think they now called Digital Symphony or something like that)
It are the 150 MIPS versions.