PCM5.1 & lossless audio discussion - split thread from A Knight's Tale review (1 Viewer)

[Roger Dressler]

I would say that given the capacities of these new formats, there's no excuse not to use 640 kbps for either format. HD DVD has the option to go higher, but you mentioned that there is insufficient space for TrueHD. At the end of the day, no disc should go out with unused bits after all the elements are decided. Wind up either the video or the audio bitrate, or both, as best serves the product.

 

[JediFonger]

the most optimal philosophy would be to provide the highest quality a/v and then let the playback device scale it down to be backwards compatible.

i had always imagined a device that can playback uncompressed audio and video film but scale it back to NTSC & stereo for people that still have it, but scale to 1080p or uncompressed x.1 or ultra definition when that comes along.

come out with a product ONCE and have people buy the license to watch a movie ONCE but always scalable.

 

[DaViD Boulet]

Agreed.

I think that in practice a 1080p format with lossless/high-res audio might come close to our imagined goal.

 

[JediFonger]

yeah, but my lofty goal was truly uncompressed film and studio grade audio that downscales via the player to whatever "lower" quality consumer electronics were at. then as the CE catches up to uncompressed video and audio, the player would induce less scaling and compression.

 

[DaViD Boulet]

Regarding audio, if we get 24/96 or even 24/48 lossless we *are* getting studio-grade copies of those masters.

Regarding video, aside from 4K native scans, the vastly more transparent-encoding we're seeing with VC1 on HD DVD (and soon BD) at 1920 x 1080p resolution is also very close to "studio" quality. Actually, most technicians haven't even seen images as good as we're seeing on our 1080p projectors in their own labs. Still room for learning and improving... but we really are very, very close to the real goal of replicating the look/feel of that original film authentically in our private viewing rooms maintaining proper integrity to the film original.

Had they provided both formats with the ability to encode greater color depth for HDMI 1.3 it would have been ideal.

 

[JediFonger]

oh you know what i mean =).

re: video, i was thinking 4k masters stored on somn like Holographic video discs.

 

[Michael TLV]

Greetings

So why does the Dolby site always talk about DD+ as being 3 mbps and higher if it is just 640 kbps?

Is it 3 mbps on the disc ... and only 640 kbps out the digital outputs or is it 3 mbps (quality) out the analog 5.1 outputs?

Regards

 

[DaViD Boulet]

I assumed that DD+ could possibly provide even better quality given various features (like 7.1 encoding) etc., but that maybe the current implimentation on HD DVD with 5.1 tracks just happens to be "approximating" what we're seeing with native 640 DD on Blu-ray?

 

[Michael TLV]

Greetings

Thanks Dave.

I see at another part of their site that HD DVD max is 3 mbps.

Also heard that Universal does 1.5 mbps DD+ ... then compared to 640 kbps DD+ of Warner titles ...

Given all this ... I guess the DTS 1.5 mbps tracks when available are definitely a viable alternative afterall.

Regards

 

[ChristopherDAC]

The packetising structure of DD+ on HD DVD would allow for a series of bitrates : 504 kbps with six blocks per coding frame (most efficient), 1508 with three blocks per frame, 2016 with two, or 3024 kbps with one block per coding frame (least efficient), if my reading of the relevant technical papers is correct.

 

[Xavier Roy-Bois]

It just sad not to have THE EXACT technical details about DD+ tracks.

When DTS said they use 1500 mbps on their website we have exactly the same bits on our dvds or HD DVDS. I like companies who deliver what they claim on their web site... I mean don"t tell anybody you will use 6 mbps if in the fact you will only use 640 kbps or maybe 1.5 mbps some times. I don"t want to be hard on DOLBY because I have always been a great fan of their new technologies. But I would like them to put real facts on their web site and not claiming technical stuff that they will not use.

Roger, please If you can explain to us once and for all .

Thanks !

 

[DaViD Boulet]

In fairness to Dolby,

they aren't the ones authoring the HD DVDs. Dolby has provided a very flexible suite of tools with their codecs... DD+ is a "swiss army knife" of audio codecs if you will. The studio has immense flexibility about how to impliment features based on the requirements of their disc production and content.

I agree that it would be nice to have clarity about what's going on with each soundtrack implimentation, but perhaps the solution is to have an agreed-upon/industry standard for how disc packaging is labeled to make these things clear...but that's a *studio* issue, not a Dolby one.

 

[Roger Dressler]

DTS makes some DVDs, so they would be in control of the bitrates. They now report that most DVDs were made with half bitrate, 768 kbps. If you look at their info on DTS-HD, it says "All DTS-HD encoded content contains the original DTS 1.5 Mbps core," but in fine print it says "In certain instances Blu-ray or HD DVD content encoded in DTS-HD may not contain the full DTS 1.5 Mbps core." Doesn't say what it will be. So I don't see their situation as being any more clear than Dolby's.

We're dealing with very flexible codecs and delivery formats. No longer is it a CD with narrowly defined parameters. Same is the case with DTV, satellite radio, MP3. etc. It can certainly be a challenge to get one's head wrapped around it. Luckily we have HTF to help!

 

[Michael Osadciw]

Thanks Roger for clearing up many so many questions. Your contribution is appreciated. You are so correct in saying that this is all unlike CDs narrowly defined parameters...it's really something to get the head wrapped around.

Mike

 

[Dan Hitchman]

Maybe we wouldn't have to have as much confusion if archival, master grade Dolby TrueHD became the defacto audio standard for all releases. The DD+ codec would only be a back up (just like DD or DTS was only a back up for the MLP high res. track on DVD-Audio), and need not take up a lot of space (like only 640 kilobits/sec).

 

[DaViD Boulet]

And on BD the Dolby True HD would be sufficient because it would contain a DD 640 core already (and I beleive all HD DVD players will eventually support 5.1 decoding and transcoding to DTS/DD as well).

 

[Lee-c]

DaViD Boulet: Is it possible to access the files on a movie DVD, turn off the dialog normalization setting (change flag to 0), copy the corrected movie back to a blank disk and then watch the movie without this annoying problem (for those that don't have DVD players where you can manually switch it off on the player itself)?

 

[Roger Dressler]

There aren't any players that offer a switch for Dialog Normalization on/off. What is the annoyance it causes you?

 

[DaViD Boulet]

Hey Roger,

If Lee is thinking what I'm thinking, he's just trying to get as "direct" a reproduction of the signal as possible with the least amount of additional DSP. I understand the theory of how dialog-norm shouldn't degrade audio performance to any significant degree based on what you've shared... but I can't help but notice how the few DVDs I have where dialog norm was not applied (like the DEHT mix on Lion King... according to the mixing engineer) sound subjectively better to my ears. By "better" I don't mean louder... I mean subtleties like a greater sense space, musical textures and the like. I haven't had the opportunity to judge the same sound mix with/without dialog norm applied to do a direct-a/b so none of this is being stated as an absolute... but my ears still seem to indicate that something's sounding better with the tracks where dialog norm isn't being applied.

 

[Lee-c]

Exactly, since David said he noticed a difference in sound quality when he heard such a movie soundtrack without dialog normalization, I wanted to know if there is a way to turn the diag norm flag off in the movie files themselves, so the soundtrack never goes through this processing. In case one doesn't have a switch on the player itself to turn it off manually. So, can this be changed in the files on the movie disk?