BD-Audio format - Blu-ray Forum

mlts22 · 01-18-2006, 04:45 AM

This sounds crazy right now, but does Blu-ray provide a standard, similar to SACD or DVD-Audio?

Blue · 01-18-2006, 08:20 AM

There is no dedicated Audio only Format, but the specifications allow for a Turbo charged Dolby Digital and DTS that both companies call lossless - so presumably there is nothing to stop an Audio Disk - it will just be black video.

James Morrow · 01-18-2006, 09:44 AM

... but a maximum of 96/24 multichannel isn't high resolution - lossless or not. 192/24 is audibly much better than 96/24 (on a good system), along with DSD (SACD). Given the higher capacity and data transfer date of BD surely we could have at least SACD and/or multichannel 192/24 audio?

thunderhawk · 01-18-2006, 01:30 PM

Quote:

Originally Posted by James Morrow

... but a maximum of 96/24 multichannel isn't high resolution - lossless or not. 192/24 is audibly much better than 96/24 (on a good system), along with DSD (SACD).

Argh, what's the point of haveing a 192 kHz system for playback use? Most audiophiles (I'm talking about +90% here) don't hear the difference between the high compression standards (MP3 @ VBR, WMA @ VBR, ACC @ VBR,..) and normal CD quality, while there is a big difference in size.
Ofcourse 96 kHz will be awesome to hear and will sound better and will impress more. 192 kHz is good for studio usage, when you have to convert a lot, so there a higher max. frequency does pay off to reduce artifacts. But I don't believe in investing $/€ 500 more in 192 kHz equipment when you'll be able to hardly hear the difference. Even when you have a 192 kHz capable reciever, then still there are few speakers available to 'unleash' the full potential of 192 kHz. Multichannel 192/24 can theoretically be supported by Blu-ray Disc, however personally I don't feel much for it.
On paper 192/24 may seem to many times more surperior then 96/24, but in reality you'll hardly hear the difference.

James Morrow · 01-18-2006, 02:18 PM

... a major problem is that most of the music we ever hear is at CD quality or less - as a consequence our hearing adapts to what it's given. The point is that CD sound quality is very low - SACD/DVDA192 are much better, but it can take quite a while for your hearing to adapt to something it doesn't normally hear in music. Yet still SACD/DVDA192 are nowhere near reality. To use a visual analogy, you might claim that DVD quality is great, but when you see well produced 720p you're likely to agree that, yes - it's better. ... and 1080p then shows you something that's obviously better again. ... then SHDV and UHDV show you something that seems much closer to reality again.

I can tell you that there is a vast difference between 96/24 and 192/24 - and indeed between 192/24 and 384/24. but you need a high quality system and to give your hearing system time to become accustomed to it. Both audio and video can get to a standard at which the brain can't tell the difference between the recording and reality - but even 384/24 is nowhere near...

Whilst it's good to have speaker frequency response out to 100kHz or so - and it makes a very audible difference to sound quality, it's nothing to do with hearing frequencies beyond 20kHz (I'm sorry if this comes as a shock to you) but much more about the temporal resolution of the system and its phase response. Any good speakers (supertweeter or not) will clearly show the difference between 96, 192 and 384, when properly driven. Several have even gone beyond this and still the difference is clear ...

... and then of course there's DSD - currently at 2.8224MHz but clearly much better at 11.2896MHz - and without all that ultrasonic "noise-shaping" ...

... and of course you can use entropic considerations to throw away a lot of redundancy in these higher resolution systems ...

Shadowself · 01-18-2006, 03:36 PM

I need a little clarification.

When people have posted here about 96 versus 192, etc. are you talking about 96 thousand samples per second (often referred to as a 96 kHz sampling rate or a 96 kHz signal)? If so then the follow up question becomes what is the bit depth per sample? 12? 16? 20? 24?

Or are you referring to a signal that that has been compressed to a 96 kbps signal or 192 kbps signal?

As a different way to look at the topic...

There was a study done in the early 80s by the U.S. military looking at digitally sampling non linear analog signals. The outcome of the study essentially state that except for rare circumstances a sampling rate of 17 times the highest frequency of interest would allow faithful reproduction of the signal of interest. If we assume the highest range of hearing for people is never above 30 kHz then the maximum realistic sampling rate of 510,000 samples per second would be more than sufficient.

Since the loudest sounds recorded are about 160 dB (as compared to the "sound" of the Brownian motion of the air molecules themselves defined as 0 dB) this would necessitate about 27 bits per sample. Making the fairly safe assumption that the lowest order and highest order bits out of the A/D are distorted (or at least non linear) and adding bits to cover this distorted range ... a total bit depth per sample of 32 bits is probably more than sufficient.

Combining this the lowest order, true digital representation of sound would be approximately 16.3 Mbps.

But I would guess that is NOT what we are talking about here.

Getting back to topick... what are we really talking about here? Sample rates? Bit rates? Bit depths? Number of channels?

James Morrow · 01-18-2006, 04:24 PM

Hi SS, yes we're talking about reasonably high quality audio - so it's 96kHz/24bit, 192kHz/24bit, etc.. Note that 17B assumes that phase distortion caused by anti-aliasing filters is minimal within the "in-band" - generally a reasonable assumption (compare this to the vast quantities of phase distortion caused by the "brickwall" filters in 44.1kHz/48kHz systems). Note also that the maximum frequency generated by musical instruments can exceed 100kHz, and the temporal resolution of the human auditory system is typically 7 us or better - this also has implications for required sampling rate.

Nevertheless, taking 17B and B as 20kHz as a reasonable minimum gives a sample rate of 340kHz. 24 bits is the current consumer standard - but then again whilst many Hi-Fis can sound painful not many can take you beyond the threshold of pain. ... but if we're really talking fidelity, transient response, etc., certainly a few more bits would be good. Coincidentally, Intel's current PC audio standard (HD Audio) supports up to eight channels at 192kHz/32bit.

As you'd expect from 17B, 192/24 sounds much better than 96/24, ceteris paribus, whilst 384/24 sounds much better again, with higher rates sounding even better again ...

As far as number of channels is concerned, current surround sound is not true stereo, but forms a ring of sound - instead of a three-dimensional soundfield. True stereo using a dozen or more drivers placed around the room (including G_d speakers above and floor speakers below) and probably including beam-forming/steering technology, as required.

Based upon current technology I guess we're talking maybe 16 channels of 384kHz/24bit - around 150Mbps. Of course, there's plenty of lossless redundancy in there, and entropy-based compression can be used to get it down to around 12Mbps, and Blu-Ray's 54Mbps/72Mbps capabilities could be used with a 50GB disc to give HD video and superb audio simultaneously - imagine a concert on that!

.. and of course, DSD's (SACD's) 2.8224MHz/1bit system could be seriously upgraded as a viable alternative to 384/24 and higher ...

When you see the figures it's not surprising that the brain devotes almost as much processing power to audio as it does to video ...

... and where does 17B leave the perfect sound of (16bit) CD? ...

Shadowself · 01-18-2006, 05:19 PM

I was just curious as to what is actually being discussed as the Digital Cinema Standard gives

Sample rate: 48 kHz or 96 kHz
Bit depth: 24 bits per sample
Channels: 16 (though only 8 are actually defined, the rest are "suggestions")

James Morrow · 01-18-2006, 06:59 PM

They're certainly going for quality ....

OK, so it's low quality - but they have to start somewhere ...

AlexKx · 01-19-2006, 02:22 AM

I don't know what the hell you all are talking about but I am looking forward to the entire music cannon being re-released in stereo, 5.1, plus all the film related clips related to a project both new and old. This is mind blowing to me the oportunity here unlike ever before. Someone here was saying how no one are really interested but so far Universal Music seem ready and willing and planning for all of this. It makes sense to me so that there will not be c.d.s and the music d.v.d. sections in stores but all in one plus all these artists can start releasing more of their unreleased visual and audio material.

jgr757 · 02-06-2006, 08:36 PM

Quote:

Originally Posted by Blue

There is no dedicated Audio only Format, but the specifications allow for a Turbo charged Dolby Digital and DTS that both companies call lossless - so presumably there is nothing to stop an Audio Disk - it will just be black video.

Blu ray appears to be a better boob tube format/storage medium and audio again is an after thought. People's CPU cycles are attached to their eyes and this format is primary concerned with video and storage. If Dolby is attached to this medium, the audio will be pointless anyway. The amount of processing and, in essence being nothing more than a low pass filter at the end is making quality audio reproduction pointless. Audio would have done much better to brake with video during the Beta vs. VHS format wars as Beta had an outstanding 90db + dynamic range and S/N ratio w/o Dolby to wipe out the timbre of instruments by dropping the high frequencies and cutting out what was considered by many, hiss, only to have a total loss of timbral accuracy of instruments and the sound of the venue (when recording live) wiped out.

thunderhawk · 02-06-2006, 08:40 PM

Quote:

Originally Posted by jgr757

Blu ray appears to be a better boob

Mmm... I wish

Knight-Errant · 02-06-2006, 11:04 PM

Quote:

Originally Posted by thunderhawk

Mmm... I wish

Oh come on, if it comes to a contest between Blu-ray and the opposite sex, I know which I prefer :P

thunderhawk · 02-06-2006, 11:48 PM

By the way, on the audio...
Dolby True HD

http://www.dolby.com/consumer/technology/trueHD.html

DTS

http://www.dts.com/consumer/technolo...al_7sept05.pdf

~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Quote:

Originally Posted by Knight-Errant

Oh come on, if it comes to a contest between Blu-ray and the opposite sex, I know which I prefer :P

Mmm.. Though one for me =P I'm already with Blu-ray so...

dvda-sacd · 01-13-2007, 10:35 AM

Quote:

Originally Posted by James Morrow

... and then of course there's DSD - currently at 2.8224MHz but clearly much better at 11.2896MHz - and without all that ultrasonic "noise-shaping" ...

Oh yeah! That would be fantastic!

Cheers!

01-18-2006, 04:45 AM	#1
mlts22 Junior Member Member since:Jan 2006	BD-Audio format This sounds crazy right now, but does Blu-ray provide a standard, similar to SACD or DVD-Audio?

01-18-2006, 03:36 PM	#6
Shadowself Senior Member Member since:Sep 2005	Clarification needed I need a little clarification. When people have posted here about 96 versus 192, etc. are you talking about 96 thousand samples per second (often referred to as a 96 kHz sampling rate or a 96 kHz signal)? If so then the follow up question becomes what is the bit depth per sample? 12? 16? 20? 24? Or are you referring to a signal that that has been compressed to a 96 kbps signal or 192 kbps signal? As a different way to look at the topic... There was a study done in the early 80s by the U.S. military looking at digitally sampling non linear analog signals. The outcome of the study essentially state that except for rare circumstances a sampling rate of 17 times the highest frequency of interest would allow faithful reproduction of the signal of interest. If we assume the highest range of hearing for people is never above 30 kHz then the maximum realistic sampling rate of 510,000 samples per second would be more than sufficient. Since the loudest sounds recorded are about 160 dB (as compared to the "sound" of the Brownian motion of the air molecules themselves defined as 0 dB) this would necessitate about 27 bits per sample. Making the fairly safe assumption that the lowest order and highest order bits out of the A/D are distorted (or at least non linear) and adding bits to cover this distorted range ... a total bit depth per sample of 32 bits is probably more than sufficient. Combining this the lowest order, true digital representation of sound would be approximately 16.3 Mbps. But I would guess that is NOT what we are talking about here. Getting back to topick... what are we really talking about here? Sample rates? Bit rates? Bit depths? Number of channels?

01-18-2006, 05:19 PM	#8
Shadowself Senior Member Member since:Sep 2005	Just curious I was just curious as to what is actually being discussed as the Digital Cinema Standard gives Sample rate: 48 kHz or 96 kHz Bit depth: 24 bits per sample Channels: 16 (though only 8 are actually defined, the rest are "suggestions")

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01-18-2006, 08:20 AM	#2
Blue Super Moderator Top contributor Member since:Jan 2005 Location:Melbourne Australia Blu-ray collection:206	There is no dedicated Audio only Format, but the specifications allow for a Turbo charged Dolby Digital and DTS that both companies call lossless - so presumably there is nothing to stop an Audio Disk - it will just be black video.

01-18-2006, 09:44 AM	#3
James Morrow Member Member since:Jun 2004	... but a maximum of 96/24 multichannel isn't high resolution - lossless or not. 192/24 is audibly much better than 96/24 (on a good system), along with DSD (SACD). Given the higher capacity and data transfer date of BD surely we could have at least SACD and/or multichannel 192/24 audio?

01-18-2006, 02:18 PM	#5
James Morrow Member Member since:Jun 2004	... a major problem is that most of the music we ever hear is at CD quality or less - as a consequence our hearing adapts to what it's given. The point is that CD sound quality is very low - SACD/DVDA192 are much better, but it can take quite a while for your hearing to adapt to something it doesn't normally hear in music. Yet still SACD/DVDA192 are nowhere near reality. To use a visual analogy, you might claim that DVD quality is great, but when you see well produced 720p you're likely to agree that, yes - it's better. ... and 1080p then shows you something that's obviously better again. ... then SHDV and UHDV show you something that seems much closer to reality again. I can tell you that there is a vast difference between 96/24 and 192/24 - and indeed between 192/24 and 384/24. but you need a high quality system and to give your hearing system time to become accustomed to it. Both audio and video can get to a standard at which the brain can't tell the difference between the recording and reality - but even 384/24 is nowhere near... Whilst it's good to have speaker frequency response out to 100kHz or so - and it makes a very audible difference to sound quality, it's nothing to do with hearing frequencies beyond 20kHz (I'm sorry if this comes as a shock to you) but much more about the temporal resolution of the system and its phase response. Any good speakers (supertweeter or not) will clearly show the difference between 96, 192 and 384, when properly driven. Several have even gone beyond this and still the difference is clear ... ... and then of course there's DSD - currently at 2.8224MHz but clearly much better at 11.2896MHz - and without all that ultrasonic "noise-shaping" ... ... and of course you can use entropic considerations to throw away a lot of redundancy in these higher resolution systems ...

01-18-2006, 04:24 PM	#7
James Morrow Member Member since:Jun 2004	Hi SS, yes we're talking about reasonably high quality audio - so it's 96kHz/24bit, 192kHz/24bit, etc.. Note that 17B assumes that phase distortion caused by anti-aliasing filters is minimal within the "in-band" - generally a reasonable assumption (compare this to the vast quantities of phase distortion caused by the "brickwall" filters in 44.1kHz/48kHz systems). Note also that the maximum frequency generated by musical instruments can exceed 100kHz, and the temporal resolution of the human auditory system is typically 7 us or better - this also has implications for required sampling rate. Nevertheless, taking 17B and B as 20kHz as a reasonable minimum gives a sample rate of 340kHz. 24 bits is the current consumer standard - but then again whilst many Hi-Fis can sound painful not many can take you beyond the threshold of pain. ... but if we're really talking fidelity, transient response, etc., certainly a few more bits would be good. Coincidentally, Intel's current PC audio standard (HD Audio) supports up to eight channels at 192kHz/32bit. As you'd expect from 17B, 192/24 sounds much better than 96/24, ceteris paribus, whilst 384/24 sounds much better again, with higher rates sounding even better again ... As far as number of channels is concerned, current surround sound is not true stereo, but forms a ring of sound - instead of a three-dimensional soundfield. True stereo using a dozen or more drivers placed around the room (including G_d speakers above and floor speakers below) and probably including beam-forming/steering technology, as required. Based upon current technology I guess we're talking maybe 16 channels of 384kHz/24bit - around 150Mbps. Of course, there's plenty of lossless redundancy in there, and entropy-based compression can be used to get it down to around 12Mbps, and Blu-Ray's 54Mbps/72Mbps capabilities could be used with a 50GB disc to give HD video and superb audio simultaneously - imagine a concert on that! .. and of course, DSD's (SACD's) 2.8224MHz/1bit system could be seriously upgraded as a viable alternative to 384/24 and higher ... When you see the figures it's not surprising that the brain devotes almost as much processing power to audio as it does to video ... ... and where does 17B leave the perfect sound of (16bit) CD? ...

01-18-2006, 06:59 PM	#9
James Morrow Member Member since:Jun 2004	They're certainly going for quality .... OK, so it's low quality - but they have to start somewhere ...

01-19-2006, 02:22 AM	#10
AlexKx Active Member Member since:Jan 2005	I don't know what the hell you all are talking about but I am looking forward to the entire music cannon being re-released in stereo, 5.1, plus all the film related clips related to a project both new and old. This is mind blowing to me the oportunity here unlike ever before. Someone here was saying how no one are really interested but so far Universal Music seem ready and willing and planning for all of this. It makes sense to me so that there will not be c.d.s and the music d.v.d. sections in stores but all in one plus all these artists can start releasing more of their unreleased visual and audio material.

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