What Exactly Is Uncompressed Pcm Audio?

JEFF62

Active Member
Just recently bought a PS3 and so fairly new to Blu Ray. Can someone explain what Uncompressed PCM audio is. I have a home cinema system so i use 5.1 DD. But I keep seeing this option in Blu Ray menus for 5.1 uncompressed PCM audio. What exctly is it and what do you need to listen to it? I selected it once and got no sound. Just wondering what the difference is between this and 5.1 DD.
 

kingfats

Distinguished Member
Just recently bought a PS3 and so fairly new to Blu Ray. Can someone explain what Uncompressed PCM audio is. I have a home cinema system so i use 5.1 DD. But I keep seeing this option in Blu Ray menus for 5.1 uncompressed PCM audio. What exctly is it and what do you need to listen to it? I selected it once and got no sound. Just wondering what the difference is between this and 5.1 DD.
Hi mate. :)
The PS3 needs to be set to LPCM and you need an amp that can accept this over HDMI to make use of HD audio from the PS3 :cool: which internally decodes all HD audio soundtracks. :smashin:
Here's the heads up. :)

PCM
What it is: A PCM track is an exact replication of the studio master, encoded on disc without compression. The benefit to this is that it maintains the purity of the source without any loss of fidelity that may come from compression. The downside is that an uncompressed audio track takes up a tremendous amount of disc space, which may (especially on single-layer BD25 discs) negatively affect the video quality of the movie. While the Blu-ray format is capable of utilizing PCM audio up to 24-bit resolution, studios may choose to encode at 16-bit resolution instead, depending on the bit depth of the original source or concerns about conserving bandwidth (downsampling a 24-bit master to 16 bits is technically not the same thing as compression).
Level of support: All Blu-ray disc players are required to support PCM audio.
Examples of discs that use it: Almost all discs from Sony and Disney, as well as selected titles from Lionsgate and other studios.
How to get it:


Toslink or Coaxial SPDIF - SPDIF does not have enough bandwidth to carry a full 5.1 PCM signal, so the audio track will be downgraded to 2 channels only. This is generally an undesirable result.
HDMI - A PCM track can be transmitted in full quality over any version of HDMI and delivered to the receiver for D-to-A conversion and amplification.
Multi-channel analog - In this case, the player converts the PCM to analog and sends it to the receiver for amplification. The quality of the DACs in the player will determine the final audio quality. If the disc player has inferior DACs to the receiver, an HDMI connection is preferred.
:thumbsup:
 

RODCULL

Novice Member
What I can't fully understand is why the new Dolby TrueHD and DTS-HD MA formats are needed, as PCM audio seems to be mandatory for Blu-ray and also seems to be lossless (or at least uncompressed).

I can understand the older DD and DTS formats being needed for DVDs, as they were providing something otherwise unavailable.

I must be missing something?! :confused:
 

JEFF62

Active Member
Hi mate. :)
The PS3 needs to be set to LPCM and you need an amp that can accept this over HDMI to make use of HD audio from the PS3 :cool: which internally decodes all HD audio soundtracks. :smashin:
Here's the heads up. :)

PCM
What it is: A PCM track is an exact replication of the studio master, encoded on disc without compression. The benefit to this is that it maintains the purity of the source without any loss of fidelity that may come from compression. The downside is that an uncompressed audio track takes up a tremendous amount of disc space, which may (especially on single-layer BD25 discs) negatively affect the video quality of the movie. While the Blu-ray format is capable of utilizing PCM audio up to 24-bit resolution, studios may choose to encode at 16-bit resolution instead, depending on the bit depth of the original source or concerns about conserving bandwidth (downsampling a 24-bit master to 16 bits is technically not the same thing as compression).
Level of support: All Blu-ray disc players are required to support PCM audio.
Examples of discs that use it: Almost all discs from Sony and Disney, as well as selected titles from Lionsgate and other studios.
How to get it:


Toslink or Coaxial SPDIF - SPDIF does not have enough bandwidth to carry a full 5.1 PCM signal, so the audio track will be downgraded to 2 channels only. This is generally an undesirable result.
HDMI - A PCM track can be transmitted in full quality over any version of HDMI and delivered to the receiver for D-to-A conversion and amplification.
Multi-channel analog - In this case, the player converts the PCM to analog and sends it to the receiver for amplification. The quality of the DACs in the player will determine the final audio quality. If the disc player has inferior DACs to the receiver, an HDMI connection is preferred.
:thumbsup:
Thanks for informative reply. I am using an optical lead to output the sound to my home cinema system. i was just about to change the settings to LCPM when an alarming message came up telling me i could damge the speakers if they do not support it. My home cinema system is nearly two years old and is made by Acoustic Solutions. How do i know if it will support the uncompressed audio?
 

kingfats

Distinguished Member
What I can't fully understand is why the new Dolby TrueHD and DTS-HD MA formats are needed, as PCM audio seems to be mandatory for Blu-ray and also seems to be lossless (or at least uncompressed).:
Hi mate. :)
Something to do with money:confused:...........i guess.
I don't care what they call the audio track ;) as long as it's lossless :cool: that's all what matters. :D
All the best.
 

Nic Rhodes

Well-known Member
People seem to be willing to pay for 3 versions of video and 3 versions of audio codecs (lossloess), all of which do the 'same' job. It is a bit like scalers, people seem to want to buy them in players, receivers and displays nowdays, when they only need one. People seem to think it is a good thing, personally I think they are daft doing this and it is all about money and most of the punters fall for it.
 

WolfCarnage77

Novice Member
I have my PS3 set to bitstream and the sound from an uncompressed pcm 5.1 track sounds just fine. 5.1 multichannel PCM at 4.6Mb per secs. Is the PS3 detecting this by auto as I don't have it set to LPCM.
 

kingfats

Distinguished Member
I have my PS3 set to bitstream and the sound from an uncompressed pcm 5.1 track sounds just fine. 5.1 multichannel PCM at 4.6Mb per secs. Is the PS3 detecting this by auto as I don't have it set to LPCM.
Hi Thrapwinkle. :)
For TrueHD,DTS-MA you have to set the PS3 to LPCM :cool: otherwise no HD audio. :(
I presume you have a HDMI 1.3 amp? (PCM track can be sent either way then)
Cheers.
 

Blu4KHD

Well-known Member
What I can't fully understand is why the new Dolby TrueHD and DTS-HD MA formats are needed, as PCM audio seems to be mandatory for Blu-ray and also seems to be lossless (or at least uncompressed).

I can understand the older DD and DTS formats being needed for DVDs, as they were providing something otherwise unavailable.

I must be missing something?! :confused:
Eventually you will see the decline of PCM tracks on blu ray as it is in effect a space hogging audio format, Already studios have realised that the new lossless codecs ie Dolby TrueHD and DTS-HD Master Audio offer the same but in less space.
 

RODCULL

Novice Member
Thanks all for the info on the inclusion of the new lossless Dolby and DTS HD audio formats in addition to PCM. Perhaps I'm not missing something after all and there isn't any great reason for their inclusion, other than for marketing and financial purposes. As I understand it, PCM is mandatory for Blu-ray whereas Dolby TrueHD and DTS-HD Master Audio are optional. Given the space PCM audio takes up, which it seems must be available, I wonder whether the other two Dolby and DTS HD audio formats will eventually die out, once optical/coaxal interfaces have been replaced with HDMI (assuming that ever happens!).
 

Bald Monkey

Novice Member
Dolby True HD and DTS-HD MA in particular will far better suit downloads too.. :D Whilst current legal HD downloads seem to favour just a DD track, the compression from TrueHD and DTS-HD MA mean they are the only possible HD sound fromats that may be downloadable in the future IMO, I don't think we'll ever see uncompressed PCM downloads... and the core and extension nature of DTS-HD would make it easy to have various download options of various quality, depending on cost/time etc..

Also with the 'jitter' issues with HDMI ;) I'd rather have a codec I can bitstream direct to my receiver when possible.. :D
 

Bald Monkey

Novice Member
Thanks all for the info on the inclusion of the new lossless Dolby and DTS HD audio formats in addition to PCM. Perhaps I'm not missing something after all and there isn't any great reason for their inclusion, other than for marketing and financial purposes. As I understand it, PCM is mandatory for Blu-ray whereas Dolby TrueHD and DTS-HD Master Audio are optional. Given the space PCM audio takes up, which it seems must be available, I wonder whether the other two Dolby and DTS HD audio formats will eventually die out.
Nahh I see it the other way around. PCM will and is already dying out.. The studios want more space and PCM is a lazy way of getting a HD soundtrack on to disc. With no compression at all, bad on BD50's but even worse on a BD25 when space is already short!

Also downloads as mentioned above.. HD movies are avaliable in many different ways BR is just one option and IMO DTS-HD and TrueHD are far better alternatives for most of these.

The financial reasons why people like Sony use PCM is so they don't have to pay for the Dolby / DTS licencse, using PCM is to save money not the other way around..

Also if you've ever compared inplayer decoding with bitstream output which is decoded in the receiver you may find the latter is far better, many on here have, because of inherant problems with jitter on HDMI connections, which is bad enough to be audiable. PCM can't be bitstreamed as such, so is useless for these players and receivers with Bitstream capabillity.. Strangely the PS3 can't do this.. ;) which is another reason why PCM was so popular at first... It's yet again another decision made to make more money, sell more hardware and not for quality reasons... IMHO. :D
 

Nic Rhodes

Well-known Member
I think PCM is on the way out and recent disc releases would seem to support this as well.
 

RODCULL

Novice Member
Thanks again all! The overwhelming consensus certainly seems to be that the new lossless Dolby and DTS audio formats are the future, both for Blu-ray and downloads etc, with PCM dying out.

Being a newbie, and to play devils advocate ;) I still wonder whether PCM will be the future for Blu-ray (if not downloads), mainly coz':

1. It seems to be mandatory
2. It doesn't seem to incurr any licencing fees
3. It does take up considerable space, but with internet connectivity available in future players, presumably space will be available at less of a premium as any extras will be downloadable, with the disc containing only the main movie (and audio).

:devil:

I guess only time will tell! :)
 

Bald Monkey

Novice Member
I guess only time will tell! :)
:D But time is already telling... Studios that use PCM are now moving over to DTS-HD and Dolby-TrueHD.

FOX are completely DTS-HD MA

The previous HD-DVD studios also seem to be going down this route..

It's not so much what will happen but how long will PCM be around.. IMHO. :thumbsup:

What I want to know is what's the point in having both Dolby True HD and DTS-HD MA, neither seems to have a specific advantage and both should sound the same... I wonder if DTS will dominate this generation of discs I think it might??

Oh and PCM is only mandatory on players not the discs themselves... standard DD decoding is also mandatory, doesn't mean that will be the norm on BR's does it! :D
 

Nic Rhodes

Well-known Member
Thanks again all! The overwhelming consensus certainly seems to be that the new lossless Dolby and DTS audio formats are the future, both for Blu-ray and downloads etc, with PCM dying out.

Being a newbie, and to play devils advocate ;) I still wonder whether PCM will be the future for Blu-ray (if not downloads), mainly coz':

1. It seems to be mandatory
2. It doesn't seem to incurr any licencing fees
3. It does take up considerable space, but with internet connectivity available in future players, presumably space will be available at less of a premium as any extras will be downloadable, with the disc containing only the main movie (and audio).

:devil:

I guess only time will tell! :)
OKay I'm game :devil:

1. It is not mandatory on the discs, only the players.
2. Existing licence fees cover the lossless formats as well as the lossy formats which are mandatory anyway
3. My bluray player does not have internet connectivity, neither do the majority of standalones sold in the last 2 years, not that I and many other have these internet player connected up to the internet anyway.
 

Bald Monkey

Novice Member
2. Existing licence fees cover the lossless formats as well as the lossy formats which are mandatory anyway
:thumbsup: Didn't know that.. so are the costs of putting a Dobly True HD or DTS-HD MA track on a BR more?? I always presumed it was due to extra license payments. I presume it still costs a little more due to the process of encoding the audio etc.. ?? Or is adding a HD audio format such as Dolby True HD and DTS-HD a no cost option for the studios??
 

Mike Groves

Active Member
.........3. It does take up considerable space, but with internet connectivity available in future players, presumably space will be available at less of a premium as any extras will be downloadable, with the disc containing only the main movie (and audio).

:devil:

I guess only time will tell! :)
I'd love to see this happening - put the movie on the disc where it belongs & if you want all the rest of the cr*p like extras, coming attractions, blah, blah, then download them. While I have ethernet connectivity on my BD player and on my receiver, and on my PC, I most certainly would not be downloading it.

Can't see it happening though. :(
 

scumball

Distinguished Member
I presume it still costs a little more due to the process of encoding the audio etc.. ?? Or is adding a HD audio format such as Dolby True HD and DTS-HD a no cost option for the studios??
Exactly, it takes time to encode the PCM master tracks to DTS or Dolby, which will cost money one way or another....

To get uncompressed audio on a slightly older player and amp you need PCM on the disc, only the newest players and amps can actually process the new lossless formats, but then if you have PCM on the disc you really need to add a DD or DTS track for people with legacy 5.1 setups, which takes up more space and time (money). Encoding to DTS-MA and thus getting the 'core' at the same time is a one hit cost and does seem to cater for most scenarios...
 

Rsaeire

Member
:D But time is already telling... Studios that use PCM are now moving over to DTS-HD and Dolby-TrueHD.

FOX are completely DTS-HD MA

The previous HD-DVD studios also seem to be going down this route..

It's not so much what will happen but how long will PCM be around.. IMHO. :thumbsup:

What I want to know is what's the point in having both Dolby True HD and DTS-HD MA, neither seems to have a specific advantage and both should sound the same... I wonder if DTS will dominate this generation of discs I think it might??

Oh and PCM is only mandatory on players not the discs themselves... standard DD decoding is also mandatory, doesn't mean that will be the norm on BR's does it! :D
Looking at the maximum bitrate possible for both Dolby True-HD and DTS-HD MA and the current maximum bitrate of both formats on all Blu-ray titles, DTS-HD MA wins on the numbers alone.

The only title I could find that has both formats is "Close Encounters of The Third Kind: 30th Anniversary Ultimate Edition". By any chance, has anyone compared the tracks in question on this disc?
 

scumball

Distinguished Member
Looking at the maximum bitrate possible for both Dolby True-HD and DTS-HD MA and the current maximum bitrate of both formats on all Blu-ray titles, DTS-HD MA wins on the numbers alone.

The only title I could find that has both formats is "Close Encounters of The Third Kind: 30th Anniversary Ultimate Edition". By any chance, has anyone compared the tracks in question on this disc?
In all honesty bitrate is irrelavant in lossless compression, it just means Dolby is a better system if it can do lossless at a smaller file size....
 

Rsaeire

Member
In all honesty bitrate is irrelavant in lossless compression, it just means Dolby is a better system if it can do lossless at a smaller file size....
Yeah, that would make sense :rolleyes:

I've been so used to higher bitrates being better that I completely disregarded the fact that we're dealing with lossless sound.
 

Sonic67

Banned
I'd love to see this happening - put the movie on the disc where it belongs & if you want all the rest of the cr*p like extras, coming attractions, blah, blah, then download them.
On a 6GB DVD I imagine that at most the extras would be around 1GB. The same extras on a 50GB disk would be hardly noticed. Then there's still a second disk option.
 

Bald Monkey

Novice Member
On a 6GB DVD I imagine that at most the extras would be around 1GB. The same extras on a 50GB disk would be hardly noticed. Then there's still a second disk option.

Also not everyone has their machine connected to the net, (a lot of BR players don't even have ethernet connections) So who would pay what?

Would everyone pay the same prcie for the disc, if they had access to all these online extras or not?? :rolleyes:

Or would you have to pay extra to download these erm... Extras :D ??

I can't see either being popular.... ;)
 

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