LPCM or Dolby Digital to Sound Bar

[andyodell]

I started a similar thread about this so I am sorry for the second post but I have found out a little more since so am posting somthing simpler.

Basicly the Blu Ray is a BDPS370 and the Sound Bar is a CT260H

The Sound Bar has both HDMI and Optical in and the Blu Ray has both these as outputs.

I have tried different set ups using ARC etc on the Sony TV (40EX503) and it has came down to this...

LPCM or Dolby Digital.

When using Optical "Dolby Digital" shows up on the Sound Bar (thinking about it maybe even DTS with some discs)

When using HDMI which as a set up is easier only "LPCM" shows up.

So it there a best?

The other confusing thing is the Blu Ray set up options only show PCM for HDMI out - Is this different or any less to LPCM or is the Sound Bar going to do the decoding?

The only option for Dolby Digital out is through Optical it seems.

What should I be going for?

[Anonymous · Accepted solution]

Hi there.

Lets see how to tackle this.  Firstly see page 20 of the blu-ray manual : Here  (Set Audio (HDMI) - AUTO) - This should output bitsteam sound to your soundbar for decoding (and hence show DD)

My understanding of LPCM vs DD is:

When set to LPCM the decoding is done directly on the device (ie TV,bluray) then outputted to the AMP-Speakers.  When outputting in Bitsteam (ie DD) - the raw audio is outputted to the AMP for decoding then to the speakers.  If both devices decode DD, the sound is the same, but on the AMP is shows nicely as DD and not LPCM.

For me - I have a AV Receiver and have set everything to bitstream (to let the AV receiver do the decoding).  I personally think that its better to have the best device do the job. 

So for you - I would let the soundbar do the decoding of DD.

LPCM = Linear Pulse Code Modulation

DD = Dolby Digital

[andyodell]

Thanks for your reply.

So really as I can see it there is no difference?  I take it that the Blu Ray is actually outputting LPCM through HDMI and that is what we are hearing through the Sound Bar.

Using Optical it is the Sound Bar that is doing the decoding so it shows Dolby Digital.

Over all there is no difference in sound then? - This is only a 2.1 system anyway.

Using HDMI only will work better for auto switching etc (now just need to work out why the Sound Bar isnt switching back to the TiVo audio output when switching the Blu Ray off, only a minor thing)

Thanks again.  Hope I have got this now!

[Anonymous]

Ive re-editted my original repy - I wouldnt worry about 5.1 surround sound, as the soundbar is 2.1 (LPCM supports 8 channels, ie 7.1)

When LPCM is showing on the soundbar - the bluray player is decoding the raw audio stream into DD, and then outputs that decoded stream to the Soundbar (no further processing is done) which is then to the speakers.  Since the bluray is decoding the stream, the soundbar will show LPCM (a generic term i guess).  If the soundbar was decoding it, therefore it would show DD.

[andyodell]

Thank you.  This is explained well.

I have both optical and HDMI hooked up at the moment.  For now I have chosen HDMI as Powering up and Down all works well together.  With the HDMI control option turned on however whenever I pause and then play the Blu Ray again it switches to HDMI from Optical.  The only way I can see around this is turning off the control for HDMI and then just having to choose the AV on the TV and Choose the Optical also on the Sound Bar.

I can see there are ups and downs for both.