Bluray Audio Format Confusion

[Johnloudb]

Okay, all these different audio formats have always confused me. On the back of this Jeff Beck Bluray disc "Live at Ronnie Scotts" it lists the audio format as LPCM stereo, Dolby Digital 5.1, DTS HD Master Audio.

LPCM (Lossless Pulse Code Modulation) Stereo, is what I'm interested in since I don't have surround sound. So does this mean I get the full resolution of DTS HD Master Audio in stereo. Some discs give the LPCM resolution as 24bit/96kHz, or 24bit/48kHz like on some True Audio Blurays I have.

On my Sony Blueray disc player it has the option to downmix to stereo or Left/Right. Is Left/Right just like left and right without the center channel? It definitely sounds better though ... more open, detailed, musical.

I think when I set my player to down sample to PCM it reduces the resolution. Note, it says PCM Stereo not LPCM Stereo. But I have my Bluray output set to stereo not multichannel.

They of course don't offer any details in the instructions. This player is True Audio capable but not DTS HD MA capable. Soooo .... not sure what to think. My dad says movies usually sound much better than our Benchmark processor. But the Benchmark sounds better than the Bluray player when playing CDs.

Well, just curious about this. I notice that music on DTS HD MA also allows for LPCM output. So that's nice, I think. Probably 24bit/96kHz or could that be 24bit/192kHz? They make this so simple really. :lol:

[bigburner]

Hi John,

In Oppo-land down-mix mode means mixing multi-channel audio to 2-channel stereo output. For original multi-channel content the surround and centre channels are mixed with the left and right front channels.

I have sent an email to OPPO asking them if it is possible to get the full resolution of DTS HD Master Audio when using the 2-channel analogue output on their BDP-83 blu-ray player. Like you I am a stereo guy and need to know this before making a purchase.

Nigel.

[Johnloudb]

Ok, that makes sense. I was missing the key word "Down-Mix," so down-mix left/right seems to give a high resolution output. And down-mix PCM seems to give standard CD resolution. The sound is good but more closed in, and sounds much like the sound from the Benchmark. Down-mix left/right is really dynamic, musical and open sounding.

I have an Oppo DVD player and they give lots of audio output options. Be interesting to see what kind of resolution you can get in stereo playback. Let me know what you find out.

[hifiguymi]

First off, LPCM stands for Linear Pulse Code Modulation. That means the data is transfered in a constant linear fashion from the player to the processor. Things like Dolby and dts are done in packets that are encoded so they aren't susceptible to things like jitter.

The LPCM stereo track is the one you would want to listen to in your system. That is going to offer the highest resolution for two channels since your BD player doesn't offer a dtsHD decoder.

By the way, which Sony player do you have?

Eric

[Johnloudb]

I have this one: Sony ES BDP-S2000ES

I'm surprised it's still available new. I thought it was replaced.

Thanks, LPCM is LinearPCM. I first looked that up on Wikipedia and they mentioned that "LPCM is further used for the lossless encoding of audio data..." Their words ... which is where the lossless came from, as everything was jumbled up in my head.

The player only offers two options for down mixing DTS and that's down mix Left/Right or down mix PCM stereo. What's the difference? All I can say, is I like the Left/Right much better.

[littlesaint]

LPCM and PCM are pretty much synonymous. They are both uncompressed, lossless formats. All consumer digital audio (outside of DSD SACDs) starts as PCM and ends as PCM. This is what ADCs and DACs process.

TrueHD (or MLP for DVD-A) and DTS-HD MA are compressed, lossless formats. This means the PCM is compressed for storage and transport, and when uncompressed is the same as the original.

Dolby Digital (any version) and DTS (any version short of HD MA) are compressed, lossy formats. This means the PCM is compressed for storage and transport, and when uncompressed some information is lost. How much, and its affect on the sound depends on the format, the DSP(s), and your ears.

[Johnloudb]

.... and your ears.

Oh, my ears huh? Well, you never know. I guess one can only guess what kind of compression and what resolution and what sampling rate the a disc is when they don't provide any information. And what sounds good, sounds good. I guess my player is giving the playback specified for 2 channel sound provided on the disc, whatever that happens to be.

[bigburner]

John,

This is what OPPO said in reply to my email requesting information about the dedicated 2-channel analogue output on the BDP-83:

The player will be performing the DownMix from the high resolution audio track, such as DTS-HD Master or Dolby Digital TrueHD, when this track is available.

You will not be able to use the digital coaxial or optical outputs on the BDP-83 to transmit DTS-HD Master or Dolby Digital TrueHD. These outputs are always the lossy core containers.

For best performance, you will use the dedicated analog Stereo output.

Nigel.

[Johnloudb]

Thanks Nigel,

That clears it up I think. I've noticed on most movies the Benchmark DAC won't work with our Bluray player. However, when I change the down mix option to PCM Stereo instead of down mix left/right, they do work with the DAC. So, I think thats why there is a loss of fidelity ... it down mixes to 16bit/48khz to work with outboard DACs, in the PCM Stereo option.

[bigburner]

John,

To remove any doubt I also asked OPPO to define down-mix, specifically whether it can also mean downgrading the audio resolution. Their reply...

It does not. DownMix simply means that it will reduce the number of channels to the desired speaker arrangement. In this case, producing Stereo from a 5.1 or 7.1 soundtrack.

Nigel.

[Johnloudb]

Thanks Nigel,

That confused me again, at least about my Sony. So, I looked up my owners manual online:

"DTS Downmix Stereo
–Downmixes multi-channel audio signals for two channel stereo.
Lt/Rt
–Allows you to hear surround sound when the connected device has a built-in Dolby Pro Logic decoder."

I don't know anything about Dolby Pro Logic, except that I don't have surround sound. But, I guess that's why it sounds different - the sound was a bit thinner but you could hear Jeff Beck's guitar work so clearly that way. But, I guess it's not accurate.

So, down-mix stereo likely doesn't affect the resolution on the Sony either, at least via the players analog outputs.

Thanks again for the info!