LPCM vs. PPCM What the heck???

Okay, I'm confused yet again. I was fooling around with my DVD-Audio discs and as I hit the display button on for my Denon DVD 2900 I would see something like the following:

1/2 PPCM 5.1 24/96Khz

I understand the 1/2 as being one program or group of two on the particular disc. I understand the 5.1 as indicating multi-channel and I understand the 24 bit/96Khz word length and sampling rate that the disc was made with.

All of my DVD-Audio discs that I looked at had similar information except one. The information on that disc showed the following:

1/1 LPCM 2.0

This was a disc by Wayne Horvitz on the Hi Res label. Again I understand that the 1/1 is a single group or audio selection and that the 2.0 indicates a stereo program.

Here is what I don't get. What is PPCM and LPCM? I have heard of packed PCM but I do not know what that is. What is the difference? Is one better than the other? Why doesn't the LPCM not reflect a word length and sampling rate like all of my other DVD-Audio discs. Is this truly a "high resolution" disc or has Hi Res fooled me with its packaging like some of the DTS product packaged in Super Jewel Boxes but that are not truly high resolution audio?

Thanks for any answers or insight.

 

Hi Mike,

I may not be able to answer all your questions, but I'll give it a shot:

LPCM would be PCM typcially at 24/48k or 24/96 that is encoded on a DVD-V or DVD-A in an uncompressed bit stream. Can be played back on most any DVD player via analog ouputs and sometimes can be output via its highest resolution, 24/96, via coax or optical.

Packed PCM is typically PCM that has been compressed or "packed" to fit on the DVD-A bitrate. A DVD-A player contains the algorithm to unpack it losslessly to 5.1 24/96 or stereo 24/192. PPCM is true hi-rez, not sure why your player won't tell you word length or sample rate. An example of packing a bit stream would be like this:

on a 24/96 LCM disc, the bit stream may be 110000000111111 and be actually encoded like this.

on a PPCM version, it will be encoded like 11, 0"times"7, 1"times"6. Bascially eliminating redundancy in the bitstream.

 

Mike,

Sams descriptions are correct

As you know PPCM is Packed PCM it works as Sam states and on DVD-A refers to MLP or Meridian Lossless Packing as the compression method. LPCM is Linear PCM - the type found on CDs, DADs and some DVD-A's. There are many forms of PCM and whilst audio buffs generally just refer to it as PCM - here LPCM is probably used because the format could also be home to PPCM.

Sonically maybe yes - maybe no - you can store more information in the same space using PPCM which would possibly give an advantage or alternatively you could store the same content in less space. PPCM is required to utilize all the channels at their maximum resolution - So in certain circumstances PPCM is better.

Don't know - possibly just their Disk Authoring style.

Not possible to tell - even if it was DPCM unless the quantization and bit rates are given - if it sounds good though and you are happy with it I wouldn't sweat

All the best - Andrew

 

Thanks Guys

Andrew and Sam,

Thanks very much for the explanations. With regards to enjoying the Wayne Horvitz selection the answer is very much. It just aroused my curiousity when I saw the different data information.

Do either of you have an opinion about DTS 20bit/44Khz, 5.1 multi-channel product that is packaged in the same manner as high resolution DVD-Audio product? Do you feel this is deceptive? I know they actually have high rez DVD-A like some of the Queen catalog, but this just bugs me. It would seem to me they should more clearly differentiate between their two types of product. I know that many times I have been in front of a rack looking at product and other people have thought they were buying DVD-Audio product and where not. I also know that there doesn't seem to be a single location in the entire Phoenix area whether it is Tower Records, Fry's Electronics, Best Buys, Border Books, Virgin Megastores, etc., and the clerks have no clue about this stuff and are really feeding bad information to customers.

 

Mike,

Regarding those DTS discs packaged as DVD-A. Yes, it is confusing, but I think they partly do this on purpose. I'm almost to the point where a well-mastered (non-compressed) DTS disc would be favorable to some of the screechy DVD-A discs I've heard lately.