Bitstream vs. PCM

ralfemeister

30-12-2003, 04:25 PM

Hi,

I have recently invested in a new amp (Pioneer VSXC301) and 5.1 speakers (Tannoy FX5.1) to match up with my elderly but much loved Samsung DVD709.

I was sitting around the other day leafing through the amps manual enjoying a DVD in what I believed was 5.1 Dolby Digital when I realised there was no 5.1 at all, just sound coming out of all 5 speakers. According to the manual the DVD player needs to be set to PCM for MPEG2 for 5.1 to function and I set this up on day one. However, once I reset the 709 back to bitstream the little channel indicators (L,R,C,SW and RS/LS) for each speaker on the amp display appeared and sound appeared much improved.

As you can tell I'm a bit of a newbie to all this but can anyone tell me what the hell is going on with my DVD player?

Thanks

Dimmy

30-12-2003, 04:37 PM

You need to set the output of your DVD player to 'Bitstream' and leave it at that, otherwise it'll only output digital stereo signals from its digital output (and not Dolby Digital, DTS etc).

Dimmy

ralfemeister

30-12-2003, 04:44 PM

Cheers,

I have already set it to Bitstream but found it bizarre that the manual for the amp said I needed to have it set to PCM for 5.1. Does this make any sense?

On a related newbie note, the DVD has Dolby Digital and DTS logos on the front but apparently there is no onboard Dolby Digital or DTS Decoder - Presumably this is why I had to buy the amp?

Thanks again.

Dimmy

30-12-2003, 04:49 PM

The manual's talking nonsense :grin:.

'Onboard Dolby Digital & DTS Decoders' are of little use really. Even without them, you'd have needed to buy an amp. All they do is decode the digital sound information onboard and output it via six analogue 'Phono' outputs (which you then have to connect to an amplifier anyway).

The Dolby & DTS logos on the front of the player just means it can read the information for Dolby & DTS on the disc & output it via the digital output.

ralfemeister

30-12-2003, 05:24 PM

2 polite and informative answers inside 20 minutes. Who said the english gentleman was a thing of the past.

Thanks once again!

Reiner

31-12-2003, 03:23 AM

PCM is used for e.g. CD-Audio (stereo), but for DD/DTS you need to use Bitstream (or sometimes called "Raw").
If you set the output to PCM only, then DD (and maybe DTS) are downmixed, i.e. also send as PCM-stereo via the digital output.