Ask questions to Audio insider Sir Terrence

[milou6]

And tell it to Peter Bracke over at hidefdigest:

(reviewing audio for Miami Vice on BD):
" Universal continues to prove their forced move to Blu-ray from the HD DVD format is no token gesture. They've exceeded the HD DVD audio presentation (which offered a Dolby Digital Plus 5.1 track), giving us a fresh DTS-HD Lossless Master Audio 5.1 Surround (48kHz/24-bit) high-res mix. It doesn't completely fix all of the problem areas with the film's source material, but it's a heck of a lot better.

The best elements of the mix sounds can be found in the film's action sequences. Rears snap, crackle, and pop with explosions and gunfire, with pans and imaging far superior on the DTS-MA track. The mix is on the bright side (there is a harshness to all the gunplay that quickly grows tiresome), but movement of sounds in the rears is excellent, with a force of sound that fully envelopes. Dynamics in these scenes are excellent; highs are clean (if again bright) and the subwoofer noticeably stronger than before. The score by John Murphy is also impressively integrated, with wonderful score bleed throughout that is almost like an other character in the surrounds.

Unfortunately, my biggest complaint with the previous HD DVD is still present, if to a lesser degree, which is that I couldn't hear much of the dialogue. 'Miami Vice' is a very talky film, and with the plot already nearly incomprehensible, it doesn't help that dialogue sounds low and mumbled, and further obscured by score and effects. To be fair, the DTS-MA mix is much better here, with the front channel in particular sounding more pronounced even after volume level matching, but I still struggled to fully comprehend spoken words. To Universal's great credit this Blu-ray is a far superior aural presentation to the HD DVD, though still marred by its source. "

http://bluray.highdefdigest.com/1448/miamivice2006.html

[Sir Terrence]

Originally Posted by Mr. Cinema

This comment is from Joshua Zyber, commenting on DD+ and Lossless:

"They are not technically identical in bit data, obviously. But audibily, if you can submit yourself to a legitimate double-blind listening test under properly controlled circumstances and consistently tell the difference between a DD+ track and a lossless track from the same audio mix, I will give you $100.

My money is safe.

The high-resolution Dolby Digital Plus and DTS-HD High Resolution formats are lossy, but use psychoacoustic modeling to remove frequencies beyond the range of human hearing. Do you believe yourself to have better hearing than is physiologically possible for a human being?

DD+ and DTS HR are much more efficient and transparent than traditional DVD quality Dolby Digital 5.1 and DTS 5.1, which are more highly compressed and remove frequencies within the range of human hearing. There are audible differences between low-res DD 5.1 and the original master. But a high-res DD+ track and the master? Not so much."

What do you make of this post?

Not much, and quite frankly you should not make much of it either. Save yourself the trouble. Its his opinion, and he is entitled to it, though there have been a few who work at the studio I do who would have slimmed his wallet of that $100.

Keep this is mind, what is the point of removing signals that are beyond the range of human hearing, when you cannot hear them in the first place? Its beyond the range of human hearing!

[Robert Siegel]

Originally Posted by Mr. Cinema

This comment is from Joshua Zyber, commenting on DD+ and Lossless:

"They are not technically identical in bit data, obviously. But audibily, if you can submit yourself to a legitimate double-blind listening test under properly controlled circumstances and consistently tell the difference between a DD+ track and a lossless track from the same audio mix, I will give you $100.

My money is safe.

The high-resolution Dolby Digital Plus and DTS-HD High Resolution formats are lossy, but use psychoacoustic modeling to remove frequencies beyond the range of human hearing. Do you believe yourself to have better hearing than is physiologically possible for a human being?

DD+ and DTS HR are much more efficient and transparent than traditional DVD quality Dolby Digital 5.1 and DTS 5.1, which are more highly compressed and remove frequencies within the range of human hearing. There are audible differences between low-res DD 5.1 and the original master. But a high-res DD+ track and the master? Not so much."

What do you make of this post?

A friend and I decided to take 2 blu-rays and 2 hd-dvd's in which the dvd had the DD+ and the blu-ray lossless. In my opinion, and keeping in mind we all have different ears, the lossless beat the DD+ (one was PCM and the other DTS MA I think). I have commented on this before when I used to post on High Def Digest often and Joshua Zyber was always there to argue my points, which is fine, to each their own opinion, but I felt I heard a difference. This as I recall was during the period when Transformers was released on hd-dvd without a lossless track, and the hd-dvd fans were defending dd+ to the hilt, though I think deep down they all wanted a lossless track on it.

It does seem strange to me he would offer $100 when the main reviewer on the site, Peter Bracke, has said many times when comparing that the lossless buried the DD+ track. (Miami Vice reviews, The Mummy reviews and many more there).

[Clark Kent]

A key piece of information is that Joshua Zyber was a well known and vocal on-line advocate for HD DVD during the format war and openly rooted for HD DVD to beat Blu-ray. The nonsense that lossy audio sounded as good as lossless audio was a key point of propaganda pushed by the HD DVD PRG in forums when they realized most HD DVDs couldn't be released with lossless audio. Unfortunately some of the more gullible believed this argument back then and still do to this day.

[Big Daddy]

Originally Posted by merrick97

I wanted to know how much space in GB a PCM track could take up vs. a TrueHD track or DTS-HD MA track.

Thanks.

This is from Engadgethd.com.
The same 2 hour movie with a 16/24, 5.1 sound track requires 4.14 GB with LPCM vs 1.26 GB for either TrueHD or DTS HD.
http://www.engadgethd.com/2007/04/26...d-demystified/

[Bobby Henderson]

That figure on LPCM bandwidth versus lossless seems very odd. I thought Dolby TrueHD and DTS-HD Master Audio used no more than 2:1 compression ratios. The bit rates I've seen on my BD movie collection seem to suggest a 2:1 ratio on those kinds of audio tracks. That engadgethd figure seems to suggest something more along the lines of a 3:1 or 4:1 ratio.

[Big Daddy]

Originally Posted by Mr. Cinema

This comment is from Joshua Zyber, commenting on DD+ and Lossless:

But audibily, if you can submit yourself to a legitimate double-blind listening test under properly controlled circumstances and consistently tell the difference between a DD+ track and a lossless track from the same audio mix, I will give you $100.

Joshua Zyber, despite his many flaws, is not completely wrong.

A group of experts went to Dolby Labs and DTS headquarters to evaluate the new HD codecs under controlled conditions. They had a hard time distinguishing between lossy and lossless audio codecs. Here is a summary of their Dolby Labs visit:

“To get the latest scoop on these new codecs, Editor-in-Chief Geoffrey Morrison and I (David Birch-Jones) made arrangements to visit both companies’ (Dolby Labs & DTS) respective headquarters, where we would be able to hear definitive A/B comparisons that would be otherwise impossible to properly set up in our own facilities.

Our first stop was at Dolby Laboratories’ headquarters in San Francisco. After a short tour of their impressive facilities, our hosts ushered us into what one of their engineers called their “codec killer room.” The specially designed room adheres to the ITU-R BS.1161-1 critical listening evaluation specification and companion BS.1284-1 Annex document that together specify in great detail the precise conditions, procedures and protocols necessary to achieve repeatable and truly useful results in the on-going development of these codecs. A suitably high resolution 5.1 system resides in the room, with five Revel Ultima Studio full range loudspeakers, along with a Paradigm subwoofer and a stack of Bryston power amplifiers rounding out the gear.

The control panel allowed for selection between a number of sources, including the original PCM multi-channel audio track, as well as TrueHD, Dolby Digital Plus, high bitrate 640 kilobits per second (kbps)Dolby Digital, and lower 448 kbps DVD-format Dolby Digital choices that have all been through the full encode/decode process.

The computer chooses which clips are presented to the listener on a randomized basis to ensure true subjectivity, and the post-session scoring data is then entered into a database and statistically validated against the actual presentation order of the test clips. From that, the engineers can glean a useful score as to the performance of the codec compared to the reference uncompressed source clip, and the process ensures that individual biases are eliminated along the way.

Neither Geoff nor I could hear any differences between the original PCM track and the TrueHD version, which should be the case, as they’re bit-for-bit identical.

Next, we compared the original to the Dolby Digital Plus version (that codec is found on numerous BD titles, and like TrueHD, is fully backward compatible with regular Dolby Digital decoders). Even on this extremely high-end system, we couldn’t hear any difference between the uncompressed and the compressed. Then, we compared the higher bitrate (640 kbps) that is found on the Dolby Digital tracks on Blu-rays to the original. "Golden Ears" Morrison was able to hear the difference, but I, and most others in the room with us, did not. Each of us had our turn in the prime listening chair, and couldn’t know the origin of the clips or their order of presentation.

The shocker came when we compared the lower 448 kbps Dolby Digital DVD bitrate to the original. There was an audible difference, but it was only ever-so-slightly noticeable (and this is with a high end audio system in an acoustically controlled environment that is so far beyond what typical home theater systems are capable of resolving). There was just the slightest decrease in presence with the DD version, not exactly a softening of the sound, but just a tad less ambience and a similarly small tightening of the front sound-stage’s depth. Quite a remarkable result, I thought, and I was highly impressed with how much fidelity can be packed into such a relatively small amount of bit space.”

Read the entire article in the July issue of Home Entertainment magazine.
http://www.hemagazine.com/node/Dolby...PCM?page=0%2C0

[red_5ive]

Originally Posted by Big Daddy

Joshua Zyber, despite his many flaws, is not completely wrong.

A group of experts went to Dolby Labs and DTS headquarters to evaluate the new HD codecs under controlled conditions. They had a hard time distinguishing between lossy and lossless audio codecs. Here is a summary of their Dolby Labs visit:

“To get the latest scoop on these new codecs, Editor-in-Chief Geoffrey Morrison and I (David Birch-Jones) made arrangements to visit both companies’ (Dolby Labs & DTS) respective headquarters, where we would be able to hear definitive A/B comparisons that would be otherwise impossible to properly set up in our own facilities.

Our first stop was at Dolby Laboratories’ headquarters in San Francisco. After a short tour of their impressive facilities, our hosts ushered us into what one of their engineers called their “codec killer room.” The specially designed room adheres to the ITU-R BS.1161-1 critical listening evaluation specification and companion BS.1284-1 Annex document that together specify in great detail the precise conditions, procedures and protocols necessary to achieve repeatable and truly useful results in the on-going development of these codecs. A suitably high resolution 5.1 system resides in the room, with five Revel Ultima Studio full range loudspeakers, along with a Paradigm subwoofer and a stack of Bryston power amplifiers rounding out the gear.

The control panel allowed for selection between a number of sources, including the original PCM multi-channel audio track, as well as TrueHD, Dolby Digital Plus, high bitrate 640 kilobits per second (kbps)Dolby Digital, and lower 448 kbps DVD-format Dolby Digital choices that have all been through the full encode/decode process.

The computer chooses which clips are presented to the listener on a randomized basis to ensure true subjectivity, and the post-session scoring data is then entered into a database and statistically validated against the actual presentation order of the test clips. From that, the engineers can glean a useful score as to the performance of the codec compared to the reference uncompressed source clip, and the process ensures that individual biases are eliminated along the way.

Neither Geoff nor I could hear any differences between the original PCM track and the TrueHD version, which should be the case, as they’re bit-for-bit identical.

Next, we compared the original to the Dolby Digital Plus version (that codec is found on numerous BD titles, and like TrueHD, is fully backward compatible with regular Dolby Digital decoders). Even on this extremely high-end system, we couldn’t hear any difference between the uncompressed and the compressed. Then, we compared the higher bitrate (640 kbps) that is found on the Dolby Digital tracks on Blu-rays to the original. "Golden Ears" Morrison was able to hear the difference, but I, and most others in the room with us, did not. Each of us had our turn in the prime listening chair, and couldn’t know the origin of the clips or their order of presentation.

The shocker came when we compared the lower 448 kbps Dolby Digital DVD bitrate to the original. There was an audible difference, but it was only ever-so-slightly noticeable (and this is with a high end audio system in an acoustically controlled environment that is so far beyond what typical home theater systems are capable of resolving). There was just the slightest decrease in presence with the DD version, not exactly a softening of the sound, but just a tad less ambience and a similarly small tightening of the front sound-stage’s depth. Quite a remarkable result, I thought, and I was highly impressed with how much fidelity can be packed into such a relatively small amount of bit space.”

Read the entire article in the July issue of Home Entertainment magazine.
http://www.hemagazine.com/node/Dolby...PCM?page=0%2C0

I have to agree based on what I've experienced with separates and higher end gear. Rather than exposing their differences, I think the reason is that separates improve sound across the board as long as the source material isn't garbage. I honestly prefer to watch a movie in vanilla Dolby Digital 5.1 using separates versus my old setup with a receiver playing HD audio. With my old AVR running solo (used to own an Onkyo 805 and also have a Yamaha RX-V1800), the difference between HD audio and vanilla codecs were noticeable. After upgrading to separates, the gap between the HD codecs and vanilla codecs has narrowed significantly.

[Anthony P]

Joshua Zyber, despite his many flaws, is not completely wrong

but you mist the most important parts

Due to the masking of sounds that inevitably occurs during complex and bombastic passages, the best evaluation results are obtained using relatively simple program clips, limited in duration to around 10 seconds or so and on constant replay. For our limited test, our hosts chose a brief audio clip from the movie American Beauty, the so-called “Spectacular” dream sequence where Kevin Spacey’s character ruminates on his life while looking upward at the inviting Mina Suvari, barely dressed in rose petals and surrounded by additional petals that fall towards him. The track features simple, center-channel anchored dialog, along with gentle percussive bell-like notes (xylophone, perhaps?) along with even more gentle triangle bell embellishments—just the ticket for an A/B codec comparison.

yes it is easier to compare simple sounds, but simple sounds are also much easier to compress. You want to compare something chaotic (though I agree that it should be short and on replay) that uses the full 5.1, that is when the lossy CODEC (and even possibly a lossless CODEC) will need to give up some info, why not compare complete silence while you are at it? They did the exact opposit of what they should have done and even then

Morrison was able to hear the difference

so it proves that one does not need to be a dog to hear the difference (and yes I know some where deaf enough or did not pay attention enough to hear the difference, but what does that prove?

[Big Daddy]

Originally Posted by Bobby Henderson

That figure on LPCM bandwidth versus lossless seems very odd. I thought Dolby TrueHD and DTS-HD Master Audio used no more than 2:1 compression ratios. The bit rates I've seen on my BD movie collection seem to suggest a 2:1 ratio on those kinds of audio tracks. That engadgethd figure seems to suggest something more along the lines of a 3:1 or 4:1 ratio.

LPCM uses constant bit rate. Dolby TrueHD and DTS HD MA use variable bit rates.

[LembasBread]

Originally Posted by Big Daddy

Joshua Zyber, despite his many flaws, is not completely wrong.

A group of experts went to Dolby Labs and DTS headquarters to evaluate the new HD codecs under controlled conditions. They had a hard time distinguishing between lossy and lossless audio codecs. Here is a summary of their Dolby Labs visit:

“To get the latest scoop on these new codecs, Editor-in-Chief Geoffrey Morrison and I (David Birch-Jones) made arrangements to visit both companies’ (Dolby Labs & DTS) respective headquarters, where we would be able to hear definitive A/B comparisons that would be otherwise impossible to properly set up in our own facilities.

Our first stop was at Dolby Laboratories’ headquarters in San Francisco. After a short tour of their impressive facilities, our hosts ushered us into what one of their engineers called their “codec killer room.” The specially designed room adheres to the ITU-R BS.1161-1 critical listening evaluation specification and companion BS.1284-1 Annex document that together specify in great detail the precise conditions, procedures and protocols necessary to achieve repeatable and truly useful results in the on-going development of these codecs. A suitably high resolution 5.1 system resides in the room, with five Revel Ultima Studio full range loudspeakers, along with a Paradigm subwoofer and a stack of Bryston power amplifiers rounding out the gear.

The control panel allowed for selection between a number of sources, including the original PCM multi-channel audio track, as well as TrueHD, Dolby Digital Plus, high bitrate 640 kilobits per second (kbps)Dolby Digital, and lower 448 kbps DVD-format Dolby Digital choices that have all been through the full encode/decode process.

The computer chooses which clips are presented to the listener on a randomized basis to ensure true subjectivity, and the post-session scoring data is then entered into a database and statistically validated against the actual presentation order of the test clips. From that, the engineers can glean a useful score as to the performance of the codec compared to the reference uncompressed source clip, and the process ensures that individual biases are eliminated along the way.

Neither Geoff nor I could hear any differences between the original PCM track and the TrueHD version, which should be the case, as they’re bit-for-bit identical.

Next, we compared the original to the Dolby Digital Plus version (that codec is found on numerous BD titles, and like TrueHD, is fully backward compatible with regular Dolby Digital decoders). Even on this extremely high-end system, we couldn’t hear any difference between the uncompressed and the compressed. Then, we compared the higher bitrate (640 kbps) that is found on the Dolby Digital tracks on Blu-rays to the original. "Golden Ears" Morrison was able to hear the difference, but I, and most others in the room with us, did not. Each of us had our turn in the prime listening chair, and couldn’t know the origin of the clips or their order of presentation.

The shocker came when we compared the lower 448 kbps Dolby Digital DVD bitrate to the original. There was an audible difference, but it was only ever-so-slightly noticeable (and this is with a high end audio system in an acoustically controlled environment that is so far beyond what typical home theater systems are capable of resolving). There was just the slightest decrease in presence with the DD version, not exactly a softening of the sound, but just a tad less ambience and a similarly small tightening of the front sound-stage’s depth. Quite a remarkable result, I thought, and I was highly impressed with how much fidelity can be packed into such a relatively small amount of bit space.”

Read the entire article in the July issue of Home Entertainment magazine.
http://www.hemagazine.com/node/Dolby...PCM?page=0%2C0

One key flaw that renders the test, or at least the article moot, is the bit rates for the regular Dolby test are given, but not for the Dolby Digital Plus. The question I have is what bit rate were the testers listening to Dolby Digital Plus at? It can vary from 640kbps up to 6Mbps (though not on BD, but via software decoders I'm sure it can) and be 16 or 24-bit, AFAIK. Perhaps the Dolby engineers were playing Dolby Digital Plus at 6Mbps with a 24-bit resolution and this accounted for the apparent indistinguishable quality between lossy and lossless.

Also, as was mentioned, less dynamic, "simpler" scenes such as the one chosen from American Beauty are "easier" to encode; there are by nature less frequencies to have to mask and/or throw out.

[Teazle]

Originally Posted by LembasBread

Also, as was mentioned, less dynamic, "simpler" scenes such as the one chosen from American Beauty are "easier" to encode; there are by nature less frequencies to have to mask and/or throw out.

Absolutely yes. They need to redo the test for musical sequences from films such as Across the Universe and Immortal Beloved.

If on their high-end system they can't hear the difference between 640kbps DD and lossless for Beethoven's 9th (!!) or the Beatles (at 24/48!), something's wrong and it isn't with lossless.

For anyone who doubts the importance of lossless audio I give them the following argument.

Lossless is essential for music. Music is essential for film. Therefore lossless is essential for film. (By transitivity of "essential for" relation.) QED.

[milou6]

Isn't the entire Dolby Labs test influenced by Dolby's desire to showcase their format's ability to compress? It's not an independent test to start with.

[PeterTHX]

Originally Posted by milou6

Isn't the entire Dolby Labs test influenced by Dolby's desire to showcase their format's ability to compress? It's not an independent test to start with.

Independent tests (& tests in studios and at places such as Skywalker Sound) have had the same results.

Lossless is what we're aiming for, but DD @640kbps is no slouch and certainly not trash.

[Clark Kent]

Originally Posted by PeterTHX

Independent tests (& tests studios and places such as Skywalker Sound) have had the same results.

Lossless is what we're aiming for, but DD @640kbps is no slouch and certainly not trash.

I do find 640 kbps Dolby Digital tracks much better sounding than their 384 kbps DD counterparts on standard dvds. But of course lossless audio is best of all.

[Big Daddy]

Originally Posted by PeterTHX

Independent tests (& tests in studios and at places such as Skywalker Sound) have had the same results.

Lossless is what we're aiming for, but DD @640kbps is no slouch and certainly not trash.

I agree. I prefer listening to Dolby Digital or DTS on a system with separate pream/amp and high-end speakers to lossless audio on HTIB trash that most people own. There is no doubt that lossless is better, but DD, DD+ DTS, and DTS HD HR sound excellent on a good system.

[dialog_gvf]

There sure is a lot of effort being expended lately to push the claims of lack of a significant difference, and try to change people's perception of the superiority of LPCM/lossless, when Blu-ray is quite capable of always having a lossless track.

Gary

[Anthony P]

when Blu-ray is quite capable of always having a lossless track.

lol, isn't that the point the next step would be you can't tell a big difference between DD 512 and 640 then 480 @512.... to try and decrease BW needed.

The simple fact that one guy in one test could tell the difference and differentiate between the two in one test is enough to have to demand none lossy.

PS the person or team that comes 4th in the Olympics in an event is no slouch, but he is just as far from the podium as I am

[Knight-Errant]

Originally Posted by dialog_gvf

There sure is a lot of effort being expended lately to push the claims of lack of a significant difference, and try to change people's perception of the superiority of LPCM/lossless, when Blu-ray is quite capable of always having a lossless track.

Gary

Interestingly, these are exactly the arguments the DUDers used to use during the format war. "Oh you don't need lossless, oh you don't need high bitrate" blah blah.

[Sir Terrence]

Originally Posted by PeterTHX

Independent tests (& tests in studios and at places such as Skywalker Sound) have had the same results.

Lossless is what we're aiming for, but DD @640kbps is no slouch and certainly not trash.

I actually agree with you on DD at 640kbps. However, with the relationship of Dolby and THX being so close, I would not exactly considering any testing done there as a disinterested third party.

I know Soldare did a white paper submitted to AES that showed that DD was not transparent, and his group of listeners where able to distinguish between a lossless master and DD encode on a frequent basis.

I know of no other testing done on DD except test conducted by Dolby themselves.