I am unsuccessful in my attempts to actually achieve 6.1 discrete output from my Top Gun HD-DVD. I have tried both HDMI and Optical output and I get 5.1 PCM from HDMI and regular 5.1 DTS from the optical output. I can only assume that my player is decoding the DTS signal to PCM for HDMI, and decoding and re-encoding to DTS for the optical output so that it can mix the menu sounds in with it.

I have the re-release of the Top Gun DVD with the 6.1 discrete DTS track on it and it sounds amazing. I just wish I could get it from the HD-DVD.

I have an HD-A1 player that I am using and I also just bought an HD-A3 which I have not tried yet. I don't have the latest firmware, but I don't know if it will make any difference.

Bottom line: can anyone get 6.1 discrete to work?

Thanks,
Mike

It should be outputting the core track on optical, I'm not at home now to look at the box but does it say on the box it is 6.1 ? It might be only a 5.1 mix on the HD DVD ?

My receiver in 6/7.1 mode is always in DD EX or DTS ES matrixed mode when fed DD or DTS respectively. If fed DTS discrete, it'll say so, however.

Yes, it says "English 6.1 DTS-ES" on the box.

I think the issue is limited to HD-DVD's. If you watch a regular DVD, DTS-ES 6.1 discrete works fine (I assume).

When you go home, please try it and see if you can get 6.1 discrete.

Thanks.

AFAIK you'd need it to be output via HDMI to a receiver that can decode it.

I have an HDMI receiver but it sends the sound already decoded as PCM, not DTS.

Hmm... In my XA2's setup menu I can select HDMI to pass PCM, Bitstream or Auto. Have you set your HDMI to output bitstream? Mine is auto, attached to my 5.1 rig.

I have an HDMI receiver but it sends the sound already decoded as PCM, not DTS.

That's only 1/2 of it. You need an HDMI receiver that can decode the new codecs.

This has been discussed several times here.

It is technically impossible to get discrete 6.1 from any currently known HD DVD on any current player EXCEPT the HD-A35 in bitstream mode.

This is because the discs are authored in advanced mode, requiring the player to decode the audio, and no existing player has a 6.1 DTS decoder.

However this might not really be a big deal. In discrete 6.1 tracks, all the info in the back channel is also matrixed into the surrounds (a discrete 6.1 decoder subtracts that info from the surrounds). So you should be able to turn on matrix decoding in your receiver to recover the back channel.

My theory is that an HDMI connection is best for this, since there is no lossy re-encode (which might degrade the matrixed info). Just a theory. Since I have an HD-A35, I have not bothered to investigate this further.

Thanks for the information. I had not seen this mentioned before and I did a lot of searching.

I just got done hooking up my HD-A3 with an interesting result. It will send DTS out the optical output but not DTS-ES discrete 6.1 when I choose the DTS 6.1 track on Top Gun. The rest of the audio tracks output Dolby Digital on Optical as expected. This basically tells me that the player still has a DTS encoder built into it but it is disabled for anything but DTS. When selecting a DTS track and using optical output, the player decodes and then re-encodes DTS before sending it out. It sure would be nice if there was a way to just get the raw DTS track.

I will stick with HDMI and the DTS ES matrixed idea, although I wonder if Dolby Pro Logic IIx would be better in this case...

Thanks!
Mike

The NEC Emma3 is the SoC inside Gen2 and Gen3 HD DVD players.

Here is an excerpt from the "specs"

Advanced functions for HD DVD systems all on a single chip

New high definition video formats such as H.264 and VC -1 that support high image quality, Dolby Digital Plus and DTS-HD audio decoders for superior sound quality, stream processing, and HD graphics processing are all included on a single chip, greatly reducing the number of components needed to build an HD DVD player.

If I recall the HD DVD of Face Off offered DTS ES 6.1? Or was it some other DTS 6.1 format? I know at a minimum it had a menu choice of DTS 6.1 - just can't recall if it had the "ES" in there.

At any rate - for those of us with only 5.1 setups and the Toshiba A35 handling bitstream - would it even make sense to chose DTS ES 6.1 over TrueHD? Or for 5.1 setups that format is no good? Confused... thanks.

If you have a 5.1 system, might as well stick with TrueHD. Only difference I noted between the two is the DTS track was louder.

HD-A35 -> Denon 3808.

Shows as DTS-HD Hi Res. Not sure why it says that though, I thought that some SD discs also have DTS ES. Could it be that this is DTS-HD and they mislabeled the cover information?

For 5.1 setups normally the TrueHD should be better than DTS-ES 6.1 but depending on how the sound is mixed, it may not always be the case.

I just tried Top Gun again choosing Dolby True HD and DTS 6.1 and set my receiver to Dolby Pro Logic IIx using HDMI with PCM and I am happy to report that both sound tracks get decoded to the back channel nearly as if they were discrete instead of matrix decoded. An easy way to tell is at the very beginning while the credits are rolling, some scratchy voices come over the radios and they come out the back speakers but hardly any of this comes out the side rears.

I am not sure which sounds better but DTS is louder. I almost want to say the subwoofer is used more with DTS than TrueHD but I am not sure yet.

Shows as DTS-HD Hi Res. Not sure why it says that though, I thought that some SD discs also have DTS ES. Could it be that this is DTS-HD and they mislabeled the cover information?

Woah! That is very interesting! Do you have any DVD's with DTS ES 6.1 you can test to see what your receiver says? Lord of the Rings Extended Edition would be an example...

I remember watching some of my dvds on my old Marantz SR-4300 receiver where they would label a DTS-ES or DD-EX track and the ES or EX wouldn't flag my receiver. (Star Wars Epi I&II wouldn't flag the EX encoding. Manually had to set it) Have you tried enabling the ES on the receiver itself?

I just checked out the LOR extended sd-dvds and my hd-a2 outputs the 6.1 DTS without any issues! Sounded GREAT!

Hrm, well it's not outputting a discrete track, but the box art and menu only say ES, not matrixed or discrete.

Do we know of any HD DVDs with DTS-ES Discrete ? The only way to test for now might be to rip some footage from a DTS-ES Discrete DVD and dump it into a HD DVD (3X style), burn, and test.

As far as I know, Top Gun has a matrixed 6.1 DTS track, not a discrete one. This means it is just 5.1 with the center surround speaker mixed in the left and right surround speaker.

Thanks, I had been trying to play a few HD DVDs with DTS 6.1, DD ex plus (u2 ect) on the weekend and was going batty changing all the option to get it to play. I have an a1 and a Denon 2807 over HDMI.

So even though on sd dvd the a1 can out put over bitstream DTS 6.1 on HD dvds you need a A35 and a reciever with the decoder right?

I just checked out the LOR extended sd-dvds and my hd-a2 outputs the 6.1 DTS without any issues! Sounded GREAT!

You're not going to have any issues on SD-DVD's. We're talking HD movies.

I just checked out the LOR extended sd-dvds and my hd-a2 outputs the 6.1 DTS without any issues! Sounded GREAT!

Simple explanation most don't seem to understand is that hd dvd players decode all audio in the player to combine menu sounds and IME second track and sends it out as DD/DTS or PCM. SD dvds just send audio bitstream for your receiver to decode.

Wow, very informative.
I remember going through this when I rented Untouchables which says it has a DTS-ES track.
No matter what setting I changed on my A1, I couldn't get 6.1 to show up on my receiver via HDMI.
I guess that explains it.
I never tried hooking up the optical, I'll do that next time.

Wow, very informative.
I remember going through this when I rented Untouchables which says it has a DTS-ES track.
No matter what setting I changed on my A1, I couldn't get 6.1 to show up on my receiver via HDMI.
I guess that explains it.
I never tried hooking up the optical, I'll do that next time.

hooking it up with optical isn't going to get you 6.1. All the audio is decoded to 5.1 and sent out either DD or DTS.

Simple explanation most don't seem to understand is that hd dvd players decode all audio in the player to combine menu sounds and IME second track and sends it out as DD/DTS or PCM. SD dvds just send audio bitstream for your receiver to decode.

*faceplant* Duh, I go so preoccupied with the "it's DTS so it should fit on toslink" that I forgot all about that and wasted my time trying to verify the OP's findings!

I can't believe nobody pointed that out before you, man..

This has been discussed several times here.

It is technically impossible to get discrete 6.1 from any currently known HD DVD on any current player EXCEPT the HD-A35 in bitstream mode.

This is because the discs are authored in advanced mode, requiring the player to decode the audio, and no existing player has a 6.1 DTS decoder.

However this might not really be a big deal. In discrete 6.1 tracks, all the info in the back channel is also matrixed into the surrounds (a discrete 6.1 decoder subtracts that info from the surrounds). So you should be able to turn on matrix decoding in your receiver to recover the back channel.

My theory is that an HDMI connection is best for this, since there is no lossy re-encode (which might degrade the matrixed info). Just a theory. Since I have an HD-A35, I have not bothered to investigate this further.

I'm confused. I have the A35. Does this mean I should be getting 6.1 on my receiver?

I'm confused. I have the A35. Does this mean I should be getting 6.1 on my receiver?

The first answer that comes to mind is "what kind of receiver do you have and how have you connected the HD-A35 to it?"

However there is actually an interesting question lurking in here. With an HD-A35 in bitstream mode, is HDMI 1.3 required to pass a legacy audio codec?

I suspect that the answer to that question, and the issue with legacy DTS being flagged as "DTS-HD" in some cases, are related somehow.

I'm connected through HDMI. I'm guessing you still need a receiver that can receive the newer codecs regardless of your player.

In order to take advantage of the A35's capabilities, you would need an HDMI 1.3a compliant receiver.

I am guessing that when running HDMI 1.3 in bitstream mode you would lose the menu and IME sounds and the original audio track would be streamed bit for bit. This would allow any track to be played back unmolested including the DTS ES 6.1 discrete tracks. I think that the receivers that show DTS-HD are just confused because the signal is coming via HDMI 1.3 as opposed to standard HDMI or S/PDIF DTS signals.

My receiver manual states that you lose those features (IME, etc) when running HDMI 1.3 so it basically confirms that theory.

This has been discussed several times here.

It is technically impossible to get discrete 6.1 from any currently known HD DVD on any current player EXCEPT the HD-A35 in bitstream mode.

This is because the discs are authored in advanced mode, requiring the player to decode the audio, and no existing player has a 6.1 DTS decoder.

However this might not really be a big deal. In discrete 6.1 tracks, all the info in the back channel is also matrixed into the surrounds (a discrete 6.1 decoder subtracts that info from the surrounds). So you should be able to turn on matrix decoding in your receiver to recover the back channel.

My theory is that an HDMI connection is best for this, since there is no lossy re-encode (which might degrade the matrixed info). Just a theory. Since I have an HD-A35, I have not bothered to investigate this further.

This is a legacy codec not the new HBR one. This should be passed as is via both connections, depending how the player is set up.

I am guessing that when running HDMI 1.3 in bitstream mode you would lose the menu and IME sounds and the original audio track would be streamed bit for bit. This would allow any track to be played back unmolested including the DTS ES 6.1 discrete tracks.

Yes.

I think that the receivers that show DTS-HD are just confused because the signal is coming via HDMI 1.3 as opposed to standard HDMI or S/PDIF DTS signals.

No. I have seen "proper" DTS indicators from an HD DVD over HDMI.

This is a legacy codec not the new HBR one. This should be passed as is via both connections, depending how the player is set up.

No. There is no distinction between legacy sound formats and new ones as far as what the player is required to do for HD DVDs authored in advanced mode. No A35 or XA2 means no bitstream audio in *any* format (legacy or new).

In order to take advantage of the A35's capabilities, you would need an HDMI 1.3a compliant receiver.

I am guessing that when running HDMI 1.3 in bitstream mode you would lose the menu and IME sounds and the original audio track would be streamed bit for bit. This would allow any track to be played back unmolested including the DTS ES 6.1 discrete tracks. I think that the receivers that show DTS-HD are just confused because the signal is coming via HDMI 1.3 as opposed to standard HDMI or S/PDIF DTS signals.

My receiver manual states that you lose those features (IME, etc) when running HDMI 1.3 so it basically confirms that theory.

That's so strange. So the new receivers aren't able to properly decode the signal? You're still only getting 5.1 unless you switch to bitstream?

That's so strange. So the new receivers aren't able to properly decode the signal? You're still only getting 5.1 unless you switch to bitstream?

The issue is that if the player doesn't decode the audio, it can't mix the button sounds, IME tracks, etc into the audio signal, and therefore those "auxiliary" sounds are not present in the output signal at all. It has nothing to do with deficiencies in the receiver.

The issue is that if the player doesn't decode the audio, it can't mix the button sounds, IME tracks, etc into the audio signal, and therefore those "auxiliary" sounds are not present in the output signal at all. It has nothing to do with deficiencies in the receiver.

So it's the players problems? Or is this a limitation of HDMI? I'm completely perplexed.

So it's the players problems? Or is this a limitation of HDMI? I'm completely perplexed.

its the limitation of the current players. When the players coe out that can send out audio using bitstream, the receiver should be able to decode the audio.

its the limitation of the current players. When the players coe out that can send out audio using bitstream, the receiver should be able to decode the audio.

confirmed. tried top gun and we were soldiers last night after 2.7 update. reciever labeled as dts-es discrete. perfect storm was labeled as dolby tru hd ex. thought that was pretty cool.

No. There is no distinction between legacy sound formats and new ones as far as what the player is required to do for HD DVDs authored in advanced mode. No A35 or XA2 means no bitstream audio in *any* format (legacy or new).

You missed the point. but it's OK.

You missed the point. but it's OK.

Actually, I think he responded correctly. You had said that we are talking about the legacy codecs (regular DTS-ES Discrete 6.1) as opposed to the new High Bit Rate codes such as DTS-HD or Dolby Digital Plus or TrueHD, and that the legacy codecs should just work as is. This is not correct when they are on an HD-DVD. The reason is because of the menu sounds and IME sounds, etc. In order for you to hear those sounds, the original sound must be mixed with the additional sounds from the menus etc. This means that the old DTS-ES track is decoded inside the player, mixed with the menu sounds, and then re-encoded back into DTS 5.1 for optical output on 1st and 2nd generation players and DD5.1 on 3rd generation players. For HDMI it sends the decoded DTS-ES track and mixed menu sounds out as 5.1 PCM. If it wasn't for the menu and IME sounds, the tracks could be sent out in their original forms and you would have been correct.

It would be nice if they would do a firmware update to allow the original sounds to be output at the expense of the menu sounds for the legacy codecs. This *should* be possible, but does not happen currently.

Mike

confirmed. tried top gun and we were soldiers last night after 2.7 update. reciever labeled as dts-es discrete. perfect storm was labeled as dolby tru hd ex. thought that was pretty cool.

Sweet! I didn't realize that there were any Dolby Tru HD EX soundtracks out there.

So it's the players problems? Or is this a limitation of HDMI? I'm completely perplexed.

In my opinion this is a limitation of HDMI. They should come out with HDMI 1.4 or something that allows a low-bit rate stereo track to be muxed with the un-decoded audio stream. It would be the best of both worlds. Then you could send DTS-HD Master Audio or whatever you want and still have menu sounds and commentary, etc.

As it is today, you can either send the movie audio track without menu sounds etc. by using HDMI 1.3a on the player and the receiver, or you can have the player decode the movie audio track and mix in the menu sounds etc. before sending the decoded signal out the HDMI port.

An alternative that would be possible today using the older HDMI technology would be to do all the decoding in the player and applying Dolby Pro Logic IIx to it inside the player and muxing in the menu sounds etc. and then sending it out the HDMI port as 7.1 instead of 5.1 sound. That would be possible but currently no player does this.

Mike

Actually, I think he responded correctly. I agree!

It would be nice if they would do a firmware update to allow the original sounds to be output at the expense of the menu sounds for the legacy codecs. This *should* be possible, but does not happen currently.You mean on the S/PDIF output? Anyway the mixing also includes the PiP HDi commentary audio, not just button sounds. I understand that if you have selected HBR on a X35 or XA2 but you then ask for PiP that has audio, the player reverts the HDMI 1.3 output down from raw bitstream and back to linear PCM that was mixed with the commentary audio.

BTW, IMHO, this whole thread should have been in the HD DVD Players forum.

In retrospect, I agree. I wasn't sure which way it would head, but it has turned into more of a hardware discussion than a software discussion. I was thinking about the HD-DVD's that have the DTS 6.1 tracks rather than the players that play them.

Yes, S/PDIF output and also HDMI. You can send legacy bitstreams over HDMI.

You can send legacy bitstreams over HDMI.But Toshiba likely thinks since it can use 5.1 channel lossless PCM sent out via HDMI, then why do a re-encode to a lossy codec.

Remember the normal Advanced Authored HD DVD title practice is to decode, mix with button sounds/PiP commentary audio, and then send the mixed result out of the player.

This new HBR thingy seems to have taken Toshiba quite a while to react to, given the AA mixing requirments. They finally gave in and allowed native raw bitstream to those screaming audiophiles demanding it. Such people, IMHO, are expected to have money to throw around (to buy new high end HDMI 1.3 players, AVRs/Pre-Pros, etc. ;) ).

I can only assume that my player is decoding the DTS signal to PCM for HDMI, and decoding and re-encoding to DTS for the optical output so that it can mix the menu sounds in with it.Yes. The DTS decoder in the player only sees the 5.1-channel core packet and not the extension packet that contains the discrete surround-back (6th) channel. As mentioned, this isn't a problem since all the contents of the surround-back channel are duplicated in the L/R surround channels (for backwards compatibility). I will stick with HDMI and the DTS ES matrixed idea, although I wonder if Dolby Pro Logic IIx would be better in this case...It would. EX/ES decoding extracts a mono surround-back channel, which is sent to both rear speakers. PLIIx extracts stereo surround-back channels, allowing sound to move between the two rear speakers for smoother pans across the surround field. Personally, I'd leave the receiver in PLIIx mode for all 5.1 material, EX/ES encoded or not. I didn't realize that there were any Dolby Tru HD EX soundtracks out there.When a soundtrack is encoded in Surround EX, the surround-back channel is matrixed into the L/R surround channels. When this soundtrack is prepped for home video release, it will be compressed using a lossy codec (DD, DTS, DD+, DTS-HD HR) and/or packed using a lossless codec (Dolby TrueHD, DTS-HD MA) and/or simply delivered as uncompressed PCM.

In all those cases, the surround-back information is still there. It's not like encoding it in TrueHD will somehow remove it. So if a movie was mixed in Surround EX, then it remains that way irrespective of the codec (Dolby or DTS) used for storage/delivery; or even if there is no codec used (LPCM).

Sanjay

Actually, I think he responded correctly. You had said that we are talking about the legacy codecs (regular DTS-ES Discrete 6.1) as opposed to the new High Bit Rate codes such as DTS-HD or Dolby Digital Plus or TrueHD, and that the legacy codecs should just work as is. This is not correct when they are on an HD-DVD. The reason is because of the menu sounds and IME sounds, etc. In order for you to hear those sounds, the original sound must be mixed with the additional sounds from the menus etc. This means that the old DTS-ES track is decoded inside the player, mixed with the menu sounds, and then re-encoded back into DTS 5.1 for optical output on 1st and 2nd generation players and DD5.1 on 3rd generation players. For HDMI it sends the decoded DTS-ES track and mixed menu sounds out as 5.1 PCM. If it wasn't for the menu and IME sounds, the tracks could be sent out in their original forms and you would have been correct.

It would be nice if they would do a firmware update to allow the original sounds to be output at the expense of the menu sounds for the legacy codecs. This *should* be possible, but does not happen currently.

Mike
I can see why you guys are confused here, I should have been more clear. My point wasn't about what happens when this is authored as "advanced', but why would that be needed in the first place since DTS isn't even a mandatory format for HD DVD.

BTW the FW 2.7 update on the Tosh XA2 this track will passed as "ES Discrete" over HDMI [provided you use a 7.1 set up] and just DTS on the SPDIF output as you correctly assesed it already. So yeah there is FW update but it won't affect the SPDIF outputs. One more reason to get HDMI 1.3 receivers that can decode everything. :)

confirmed. tried top gun and we were soldiers last night after 2.7 update. reciever labeled as dts-es discrete. perfect storm was labeled as dolby tru hd ex. thought that was pretty cool.

With what player, and which connection ?

It would be nice if they would do a firmware update to allow the original sounds to be output at the expense of the menu sounds for the legacy codecs. This *should* be possible

Exactly ! The IME feature is nice, but not necessary when you first watch a movie, and that's when you need the best sound.

Please anyone let me know as soon as you hear from a player (HD or BD) having this feature, that's probably going to be the one I'll buy...

By the way, isn't it the case for the PS3 ?

Yes. The DTS decoder in the player only sees the 5.1-channel core packet and not the extension packet that contains the discrete surround-back (6th) channel.

Then I understand that it would take a 6.1 decoder to do that. Aren't there any players with a 6.1 decoder on the market, or soon to be ?

As mentioned, this isn't a problem since all the contents of the surround-back channel are duplicated in the L/R surround channels (for backwards compatibility).

Do you mean you can manually set the receiver to DTS-ES and get 6.1 sound from the 5.1 signal ? I assume this would be at the cost of some quality loss, but it's probably acceptable.

Personally, I'd leave the receiver in PLIIx mode for all 5.1 material, EX/ES encoded or not.

Why would the back channel be better decoded in PLIIx mode than in DTS-ES mode ? I have a 6.1 receiver, therefore only one back speaker. And also I understand that DTS uses less compression than DD.

One more reason to get HDMI 1.3 receivers that can decode everything. :)

Sure, but they're quite expensive. For the moment I'll want to stick with my cheap S/PDIF receiver, and get a full featured HDMI 1.3 one when the price is right...

Sure, but they're quite expensive. For the moment I'll want to stick with my cheap S/PDIF receiver, and get a full featured HDMI 1.3 one when the price is right...

I think what they offer right now compared to some models I owned in the past, some of these are outright bargain. My first DD receiver a Denon AVR-3600 was retailed for $1800 back in 1997. And that was 1997 dollars, if you know what I mean. ;)
I do agree that with time you will find these HDMI 1.3 receivers on every price point.

Aren't there any players with a 6.1 decoder on the market, or soon to be ?There don't seem to be any currently on the market that can decode more than the core DTS 5.1 packet. I don't know if any are coming out in the near future. Do you mean you can manually set the receiver to DTS-ES and get 6.1 sound from the 5.1 signal ?Sure. The entire contents of the 6.1-channel soundtrack is contained in the 5.1-channel core, so you can use DTS-ES matrix decoding to extract the surround-back information and send it to your rear speakers. The difference is that you'll have a matrix derived surround-back channel instead of a discrete one. I assume this would be at the cost of some quality loss, but it's probably acceptable.Discrete channels always have the potential to sound better because of greater channel separation. But modern matrix decoding is so good that you'll probably never notice the difference, especially behind you where our human hearing is weak. Certainly better than having your rear speakers go silent. Why would the back channel be better decoded in PLIIx mode than in DTS-ES mode ?Because EX/ES decoding extracts mono surround-back channel while PLIIx extracts stereo surround-back information. I have a 6.1 receiver, therefore only one back speaker.In that case there will be no difference between PLIIx and ES matrix decoding. PLIIx has the advantage when using 2 rear speakers because it can steer sound between them. And also I understand that DTS uses less compression than DD.Yes, DTS is a less efficient codec than DD so it needs a higher data rate. Same thing happens with video codecs: MPEG2 is less compressed than VC-1 because it's not as efficient.

Sanjay

Either I'm confused about the question here, or the replies.

I am seeing DTS-ES 6.1 Discrete (as identified by my receiver) from the optical output of my HD-A3 player. I don't have any HD DVDs with DTS sound to test, but I have lots of SD DVDs with DTS 6.1 sound and all of those are properly passing DTS 6.1 over the optical.

So is the question about HDMI not doing this? Or is the question about HD DVDs not having DTS 6.1?

Both HDMI and HD DVD are capabable to store and transmit DTS ES.

Both HDMI and HD DVD are capabable to store and transmit DTS ES.

not the players that can't output bitstream core audio. Currently other than xa2 and A35, all the players decode audio in the player and sent out.

Quick noob question, is this the same as DTS NEO 6?

Either I'm confused about the question here, or the replies.

I am seeing DTS-ES 6.1 Discrete (as identified by my receiver) from the optical output of my HD-A3 player. I don't have any HD DVDs with DTS sound to test, but I have lots of SD DVDs with DTS 6.1 sound and all of those are properly passing DTS 6.1 over the optical.

So is the question about HDMI not doing this? Or is the question about HD DVDs not having DTS 6.1?

The issue being discussed in this thread is about HD DVD only. For DVD, the players output the bitstream and you get 6.1.

not the players that can't output bitstream core audio. Currently other than xa2 and A35, all the players decode audio in the player and sent out.

The question was theoritical, so was my answer.

According to this picture from Dolby's website - DD+ only supports 5.1 and 7.1 Discrete:

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

Does this help?