uncompressed audio confusions

[xboxweasel]

I started getting into Blue Ray movies a while ago (it helps having a PS3 ). A lot of movies that I have looked at offer a 5.1 uncompressed audio format. Sometimes they also list 48kHz/24bit or PCM along with that description.

I have some questions:
1) What does all that mean?

2a) I am currently using a fibre optic cable for audio, and component cables for video. How is it that my older Yamaha RX-V2500 can play uncompressed audio? I did not see that as a feature in the specs. I thought that a fibre optic cable could only transfer two channel uncompressed audio (as in CD's) or up to 8
channels compressed (as in 7.1).

2b) Will my even older Yamaha RX-v1400 play back uncompressed 5.1 audio as well?

3) The other formats, like DTS HD Master, are harder to come by. Are there receivers out there that can play back these formats? Is it something that can be attained through a software upgrade (like in the case of the Anthem AVM product line)?

4) How is DTS HD Master different from the uncompressed format?

5) Until I get a receiver with HDMI and HDCP I will have to stick with DD or DTS or uncompressed audio. Correct?

6) Are uncompressed and PCM same thing? It that not how they refer to the data stored on an audio CD?

7) Are they releasing BD movies with different bit rates? Two of the movies in my BD collection specify 48kHz/24bit. The rest do not.

Thanks people.

 

[MDS]

Uncompressed audio is the raw bitstream - a sequence of numbers that represent the amplitude of the signal at points in time. The number of samples is the sampling rate (48 kHz, 96 kHz, etc) and the size of each number is the bit depth (16 bit, 24 bit, etc). So for example 16/44.1 (PCM on a compact disc) is 44,100 16 bit numbers for every second of audio (per channel).

Compressed can mean a number of different things. DD/DTS/MP3/WMA and the like are lossy compression. This is data reduction as the encoder discards things that its model of human hearing says we wouldn't hear anyway. There is also lossless compression which reduces the file size but doesn't discard any of the audio data - it would be analogous to using WinZip to zip up a text file (although the algorithm is quite different).

The uncompressed audio from the HD disc is the same in principle to two channel PCM, there are just more channels and a higher sampling rate and bit depth. The s/pdif interface, whether using coax or optical connections, cannot carry those uncompressed streams because the data rate is too high - they require HDMI.

 

[GHUNTY]

Uncompressed audio is the raw bitstream - a sequence of numbers that represent the amplitude of the signal at points in time. The number of samples is the sampling rate (48 kHz, 96 kHz, etc) and the size of each number is the bit depth (16 bit, 24 bit, etc). So for example 16/44.1 (PCM on a compact disc) is 44,100 16 bit numbers for every second of audio (per channel).

Compressed can mean a number of different things. DD/DTS/MP3/WMA and the like are lossy compression. This is data reduction as the encoder discards things that its model of human hearing says we wouldn't hear anyway. There is also lossless compression which reduces the file size but doesn't discard any of the audio data - it would be analogous to using WinZip to zip up a text file (although the algorithm is quite different).

The uncompressed audio from the HD disc is the same in principle to two channel PCM, there are just more channels and a higher sampling rate and bit depth. The s/pdif interface, whether using coax or optical connections, cannot carry those uncompressed streams because the data rate is too high - they require HDMI.

Exellent job MDS! Best explaination yet that Ive seen on all the forums! THANK YOU

 

[xboxweasel]

The uncompressed audio from the HD disc is the same in principle to two channel PCM, there are just more channels and a higher sampling rate and bit depth. The s/pdif interface, whether using coax or optical connections, cannot carry those uncompressed streams because the data rate is too high - they require HDMI.

First let me say. WOW! That was awesome. Thanks for the explanation.

So, when I select uncompressed audio, have my BD player connected to my receiver with a fibre optic line and I hear things, that means it really is not uncompressed audio.

It could be the PS3 is defaulting to DTS or DD because of something in the system setup.

 

[xboxweasel]

I checked the various audio outputs that the PS3 supports.

Via s/pdif it supports DD5.1, DTS5.1, AAC, linear PCM 2 channel at 44.1/88.2/176.4 & 48 kHz.

Via HDMI it also supports in addition to the above: linear PCM 2 channel at 96 & 192kHZ, and linear PCM 5.1 and 7.1 channels at 44.1/88.2/176.4/48/96 & 192 kHz.


I then checked the receivers manual. It states that the digital inputs are compatible with 96kHz sampling digital signals. The DACs it uses are rated at 192kHz/24bit.

I am gathering that I can enable linear PCM 2 channel output at 44.1, 88.2 and 48kHz. But not at 176.4kHz. I won't be able to use any of the 5.1 or 7.1 PCM audio streams.

It this correct?

I guess it's time for a new receiver and TV with HDMI inputs. Might as well throw in a new sub and spend an even $10k.

 

[Adam]

I guess it's time for a new receiver and TV with HDMI inputs.

Why the long face? This should be a time of celebration!

 

[xboxweasel]

Why the long face? This should be a time of celebration!

I just quit my job. Haven't found a replacement yet. Had to buy a car. And get the driveway repaved. My money is rather short these days.

 

[Adam]

I just quit my job. Haven't found a replacement yet. Had to buy a car. And get the driveway repaved. My money is rather short these days.

Ahhh, gotcha. Well, it if makes you feel any better, you're currently more advanced on your system than I am. Of course, a new job would probably feel better than that.

 

[jostenmeat]

3) The other formats, like DTS HD Master, are harder to come by. Are there receivers out there that can play back these formats? Is it something that can be attained through a software upgrade (like in the case of the Anthem AVM product line)?

4) How is DTS HD Master different from the uncompressed format?

5) Until I get a receiver with HDMI and HDCP I will have to stick with DD or DTS or uncompressed audio. Correct?

6) Are uncompressed and PCM same thing?
Thanks people.

#3 Your receiver can handle lossless formats if your player decodes. After that, all you need are the analog outputs on player and analog inputs on receiver. No need for hdmi then. However, MA is impossible to obtain at this point in time.

#4 Master is actually compressed, yet lossless. Why do we need compressed formats? Read here, I thought it to be very informative:
http://www.avsforum.com/avs-vb/showthread.php?p=10271234&&#post10271234

#5 Answered in #3

#6 In a word, yes.

 

[mtrycrafts]

Compressed can mean a number of different things. DD/DTS/MP3/WMA and the like are lossy compression. This is data reduction as the encoder discards things that its model of human hearing says we wouldn't hear anyway..

Just a small addition/correction to this. The more it is compressed like MP3, the more you discard data that is audible to some degree.

 

[xboxweasel]

What receivers / preamps are available right now that support uncompressed audio, DTS HD MASTER, DOLBY TRUE HD?

 

[MDS]

What receivers / preamps are available right now that support uncompressed audio, DTS HD MASTER, DOLBY TRUE HD?

The 2007 Onkyo lineup, the soon to be released Denons, and surely every other manufacturer in the near future.

 

[darien87]

What receivers / preamps are available right now that support uncompressed audio, DTS HD MASTER, DOLBY TRUE HD?

The new Onkyo's do and are great products. But if money is a concern, than check out the Yamaha 661. I use mine to do uncompressed audio via HDMI from my PS 3. You can get one on the web for less than $400.

In my experience uncompressed audio is kind of "hit and miss". I was absolutely blown away by the PCM track on Blackhawk Down, but not very impressed with the PCM on Underworld Evolution and Casino Royale.

 

[xboxweasel]

more ????

Okay. I just bought 300. It comes with a Dolby True HD track and PCM track.

Dolby True HD is lossless. But it can be compressed.

PCM is uncompressed and lossless. But I have seen audio tracks on BD movies listed under both. Are they the same or not?

How do they differ? What about DTS HD Master? Are there 3 high definition audio formats now?

Too many choices. Not healthy.


PS: I use a PS3 to playback BD movies. I can select either DD 5.1 or uncompressed 5.1 playback. Both produce audio. In the case of uncompressed the PS3 must be converting it to DD 5.1.

 

[jostenmeat]

...Dolby True HD is lossless. But it can be compressed.

PCM is uncompressed and lossless. But I have seen audio tracks on BD movies listed under both. Are they the same or not?

How do they differ? What about DTS HD Master? Are there 3 high definition audio formats now?

They are not the same. There is PCM, and the 3 new formats. DTS-HD Master is impossible to obtain right now, regardless of hdmi vs analogs.

The other DTS format, the HR version, is very lossy in comparison to MA and THD. Without having to buy any new receiver, etc, a simple optical/coax will give you the improved core at about 1.5 mps, being twice the former DTS' 768 kbs.

Just read around the forums. Its all over everywhere.

For your reference, a BD spec list with audio format used per disc (look under "audio" on the right):
http://www.blu-raystats.com/index.php

 

[avaserfi]

And wouldn't you guys also agree that no compression at all is better than any compression? Thus, uncompressed audio is theoretically better than DTS-MA and Dolby TruHD?

Theoretically maybe, but audibly? If the compression is truly lossless as these claim to be then who cares? If they both carry the same frequencies and just do it in different ways it doesn't matter to me. Thats why all my CDs are stored on my computer in lossless, yet compressed, files.

 

[AcuDefTechGuy]

Theoretically maybe, but audibly? If the compression is truly lossless as these claim to be then who cares? If they both carry the same frequencies and just do it in different ways it doesn't matter to me. Thats why all my CDs are stored on my computer in lossless, yet compressed, files.

Oh, I agree 100%. I can't hear a difference. When sound level matched, I'm not sure I can even tell a difference between DTS-MA and plain DTS or Dolby TruHD and plain Dolby Digital.
For example, on Batman Begins HDDVD, when I switch back betweem DD and TruHD, I have a hard time hearing the difference that critics have claimed.

I just e-mailed the editor of "The Audio Critic" regarding all these sound formats.
He wrote me back and said, "multi-channel music is over-rated, and all multi-channel formats for movies are GOOD ENOUGH."
I guess that means TAC doesn't care all that much about all these new surround sound formats.

 

[no. 5]

Theoretically maybe, but audibly? If the compression is truly lossless as these claim to be then who cares? If they both carry the same frequencies and just do it in different ways it doesn't matter to me. Thats why all my CDs are stored on my computer in lossless, yet compressed, files.

Exactly, it's a 'perceptual' compression, the intent of which is to sound almost, if not completely, indistinguishable form the original.

 

[Johnd]

He wrote me back and said, "multi-channel music is over-rated...

I never heard of him, but does he understand that "multi-channel music" includes stereo? Furthermore, dare I say this critic has never heard sacds' such as dsoth or bia on studio 100's via a Denon 2900 and a Denon 5803. Let me tell you it's a real trip. Or maybe he has, and he is just not so aurally perceptive...like so many people.

 

[no. 5]

Furthermore, dare I say this critic has never heard sacds' such as dsoth or bia on studio 100's via a Denon 2900 and a Denon 5803.

Nah, I think he's just cranky.