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

[Xavier Roy-Bois]

David you should try Paramount hd-dvds because they all include DTS tracks at 1500 kbps along with the DD+ track. By the comments of people listening to them the DD+ track always sound better practically than the full DTS track even using coaxial input. For those using the analogue input the DD+ track is a KILLER !

Try SKY CAPTAIN, SAHARA, AEON FLUX, WE WHERE SOLDIERS ( the best DD+ track ) and you should convinced that DD+ is here to stay !


Regarding Warner"s hd dvds it seems that SWORDFISH is getting the better improvement of the lot. Comparing the standard dvd and the Hd version is a revelation. See Dvd File review to undestand it :

http://www.dvdfile.com/index.php?opt...=5575&Itemid=3

 

[Roger Dressler]

Thanks much for this info. I'm really glad that both D-VHS and the Warner HD discs mark an improvement for you. I feel the same. Aside from the sheer increase in bitrate over LD/DVD, the encoder parameters are somewhat changed as they have more bits to work with. More of the data, for example, is devoted to the very high portion of the spectrum, above 14 kHz or thereabouts. One would not think that's so important, but it does improve the openness and "air" of the space.

BD should sound equal or better than D-VHS, as it will use 640 instead of 576 kbps DD.

 

[AndreGB]

Wow! This conversation is amazing! Thank you all participating on this.

 

[JediFonger]

1. what would be the "default" diag normalization on TrueHD if there is any?

2. many comments in this thread have brought up an interesting feeling that i've had since the inception of DVD's but wasn't able to verbalize =). when you watch a great mix at a properly calibrated cinema (like TAP certified) it's just hard to beat. when i come home and watch the same title on a HT (any HT) there's just somn missing on the audio side. now i know what it is =). hopefully we'll get more and more TrueHD/lossless audio attached to newer HD discs.

 

[DaViD Boulet]

Roger,

Your confirmation would be appreciated. Are you saying that in a 5.1 configuration that the DD+ on HD DVD provides the same sound quality as 640 kbps DD on Blu-ray? In other words, in 5.1 mode is the added funcationality of DD+ only really being used on HD DVD to increase the bit-rate beyond DVD's conventional limit of 448?

If "plain" DD at 640 on BD in 5.1 is the *same* as DD+ on HD DVD in 5.1 it would be great to know.

So much to learn!

 

[ChristopherDAC]

I've been enjoying this, partly because I had such fun reading the technical papers, and it's good to have some of my conclusions confirmed. No, I'm not a usual person!

My impression is that the usual bitrate for 5.1 DD+ on HD-DVD would be 504 kbps, which uses the full-length 6-block coding frame. If you don't use that, it locks out most of the new coding tools, and the coding itself gets less efficient, which seems to me as though it would obviate the advantage of the higher bitrate. Because of the better coding tools, including a somewhat more efficient DCT-exponent coding scheme, and in particular one which uses the Discrete Sine Transform to add phase values to frequency bands which are blended [mostly highs], I think it would come out about as well as 640 kbps standard DD.
640 kbps is, of course, twice the theatrical bitrate, and on most material I'd expect it to be high enough to avoid using some of the bitrate-reduction techniques which have the most compromising effect on audio quality. In particular, I've always been suspicious of the high-frequency trunking technique, because the main effect of high frequencies is to affect the sound of the lows, and the output waveshape is extremely variable under phase error.
The result would be something like tape-head azimuth error, and I think that would be about right to account for the subtle feeling of dissatisfaction, lack of "smoothness" or "spaciousness" or "air", which some people find in DVD and LD Dolby Digital soundtracks.

 

[Xavier Roy-Bois]

I would like to have comments from DOLBY, Warner, Paramount and UNIVERSAL to give us THE EXACT tech details on HD DVD DD+ tracks. Because why DOLBY is claiming a minimum of 3 mbps for bit rate performance on their web site if Warner is using only 504 kbps ? And the fact that a DD+ track win a full DTS track at 1500 kbps ?And I just don"t buy the fact that a DD BLU-RAY will equal a DD+ HD DVD.

I want real response with tech and details .

Thanks !

 

[Roger Dressler]

There is no difference in how dialnorm is calculated between DD, DD+, and TrueHD. It's measured on the source PCM, then encoded into the bitstream.

 

[Roger Dressler]

I cannot say that we have attempted to drill down to the 99th degree. There are some differences, such as the 3-block frames in HD DVD vs the 6-block frames in BD (at this data rate). I cannot tell you what that will translate to in sound quality, if any. We'll just have to listen carefully to see what comes out.

 

[DaViD Boulet]

Thanks for the particpation in this thread Roger.

Could you answer the question this way then.

If you had a 5.1 DD track and didn't have space (let's say) for Dolby True HD lossless, then what would be the "best" way to encode it on each format... DD+ on HD DVD and 640 DD on BD? You said earlier that there was no reason to go to DD+ on BD since the mix was limited to 5.1 channels. Is this the case?

I can understand how subjective it can be to evaluate resultant sound quality so I'm not asking for a definitive statement on that... but do you feel that the "optimial" way to encode a comparable 5.1 mix on both formats would be DD+ on HD DVD and 640 DD on BD?

It's interesting given how the same VC1 encoding could be used on both formats but apparently not the same Dolby Digital encoding!

 

[DeeF]

I don't understand the difference between the various terms, but I have a question. In order to get any sound at all from my new Toshiba HD-A1 (for HD-DVDs), I have to set Audio out to PCM (going through coaxial to my Boston Acoustics surround sound system). The sound seems to be at a lower volume level. But when I watch a DVD, in order to get 5.1 sound, I have to reset the Audio to Bitstream.

What am I missing here?

 

[DaViD Boulet]

Hey Dee,

If you set the output to PCM via coax/SPDIF, then you'll be getting 2.0 stereo LCPM only. Setting to "bitstream" over coax should work much better... leave it set to that. In the case of Dolby True HD it will convert it to 2.0 LPCM anyway since that's what the internal decoder does. And with DD+ HD DVD tracks it will decompress them internally and re-encode them as DTS at 1500 kbps for coax which sounds really, really good.

Can you decode DTS?

If so, then always leave your output set to bitstream.

Again, LPCM over coax/spdif is only spec.ed up to two channels so saying "PCM" will take everything and just downmix to 2.0 stereo. That's your problem!

 

[DeeF]

David, there's only one problem (but it's a big one). When I set the Audio out to Bitstream on the Toshiba (for HD-DVDs), there's no sound at all. Nada. Zip. Silence.

But, it will play my DVDs fine. Hence, my question here.

 

[DaViD Boulet]

Dee,

do you have DTS decoding in your recevier/audio decoder?

 

[DeeF]

I guess not. I always thought I did, because I thought the DVD players did it for me.

 

[DaViD Boulet]

A dts-enabled DVD player just means that it can read and pass the DTS bistream out the digital coax output to your receiver...

but whether DD or DTS it's still up to your receiver to do the decoding unless you're using the 5.1-channel analog output of your DVD player and feeding the 5.1 analog input on the receiver with the already-fully-decoded signal (and yes, some DVD players can do this for DTS as well as DD to provide analog 5.1 output from both).

If you have 5.1 analog inputs on your receiver you will get the ***BEST*** sound quality from the Toshiba A1 by using the 5.1 analog output of the player and feeding your receiver this way. In fact, that way you'll get the full DD+ sound quality right off the bat.

If your recevier can't accept a 5.1 analog input, then it's time to get a new receiver... one that can do DTS in addition to DD. The Toshiba is basically converting the DD+ soundtracks to DTS to send over coax since no receiver can do DD+ yet (and it won't ever work over coax... you'd need hdmi 1.3 to do it in the future if you wanted to do all decoding in the receiver).

Can you send the audio in 5.1 analog form between the player and receiver for the moment? That would get some more life out of your receiver in the meantime and sound *fantastic* with HD DVD software.

 

[DeeF]

It isn't a receiver. It's a Boston Acoustics Surround Sound system, bought 6 years ago for $1000. It only has a single optical input, a single coaxial input, and 2 sets of stereo RCA inputs. All these inputs can be found on the back of the subwoofer box.

Sadly, I think I'm out of luck here, and I'm a little annoyed about it.

 

[DeeF]

Maybe there's a receiver which could go between my BA Digital Theater and the players?

 

[DaViD Boulet]

Yep... you're out of luck and basically will be stuck switching from LPCM to bistream when you swictch from HD DVD and DVD and vice versa.

At least now I hope you understand what's going on... that with HD DVD you're basically getting a DTS signal over your coax in bitstream which your BA home-theater-in-a-box system apparently doesn't know how to decode. And then switching to LCPM basically drops you to 2.0 stereo over coax so you lose your 5.1 when listening to DVD.

I know that you're something of a music guy so I'd actually suggest that it's time you start to plan your new audio system. If the BA speakers are satisfying for you, you could actually use them and drive them directly from a new receiver so you don't have to all of your upgrading (speakers and receiver) at the same time. Chances are you could easily feed the BA sub via the subwoofer output from a recevier and use it as a "normal" sub driving the smaller satelites from the recevier's power as long as your receiver has a crossover high enough to work well with them.

Either way... time to start planning that next audio purchase. I *promise* you'll be amazed at how much better your sound is when you do, and if you want some help planning a budget-audio system that delivers real satisfaction we could have that conversation off-thread so it won't hijack this thread's discussion.

dave

 

[DeeF]

Kool! I sent you a PM.