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Dolby Digital Plus to be announced at NAB


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#41 of 58 OFFLINE   Kevin C Brown

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Posted April 22 2004 - 12:36 PM

I believe that full bit rate DTS is 750-ish, and 1/2 rate is 384 or so. 1.5Mb/s is LPCM (1.411 or something), and I don't think DTS goes anywhere near that. Not for movie soundtracks anyway.
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#42 of 58 OFFLINE   Richard Paul

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Posted April 22 2004 - 02:11 PM

When my thread was merged into this one many people on this thread may have missed my overview of the DD+. My overview of DD+ can be found here as the second post on the first page of this thread. It explains how many channels can be supported along what information I could find at the time.

Roger, since the ATSC candidate standard already mentioned that DD+ could support up to 14 channels could you confirm that the DD+ standard submitted for HD-DVD would have the same capability? Would DD+ have a maximum bit rate of up to 6 Megabits as this article states? Also what is the highest bit rate that a single 5.1 channel independent audio stream can have? I know I'm asking many questions but this is the first new codec by Dolby since Dolby Digital and I'm very interested in any information on it.

#43 of 58 OFFLINE   Lewis Besze

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Posted April 22 2004 - 03:20 PM

Half rate DTS is 754 kbps, full bitrate DTS is 1506 kbps[DVD, LD was slightly lower, full bit rate only] roughly same as the PCM,however DTS slice that rate for 6 channels, PCM is only 2ch,which is why there is compression roughly 4:1 for DTS at full bit rate.

#44 of 58 OFFLINE   Roger Dressler

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Posted April 22 2004 - 05:44 PM

Richard wrote: >>Roger, since the ATSC candidate standard already mentioned that DD+ could support up to 14 channels could you confirm that the DD+ standard submitted for HD-DVD would have the same capability?<< There is no direct connection between what a codec supports and what a format supports when using that codec. For example, Dolby Digital allows 640 kbps, but DVD limits to 448 kbps. MLP allows up to 32 channels, but DVD-A limits to 6. For DD+, Dolby designed in enough room to grow in several dimensions, none of which we hope is maxed out any time soon! >>Would DD+ have a maximum bit rate of up to 6 Megabits as this article states? Also what is the highest bit rate that a single 5.1 channel independent audio stream can have? I know I'm asking many questions but this is the first new codec by Dolby since Dolby Digital and I'm very interested in any information on it.<< Yes, technically 6 Mbps is possible in DD+ and all of it can be used for one 5.1 program if one wanted. This figure derives from the maximim throughput based on the coding frame and current Dolby Digital DSP input buffer sizes, and not from any practical need to use those bitrates. Don't expect to see such rates except for lossless or PCM audio.
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#45 of 58 OFFLINE   Kevin C Brown

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Posted April 22 2004 - 06:13 PM

Lewis- So I was half right. Posted Image Thanks for the correction!
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#46 of 58 OFFLINE   Cary P

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Posted April 23 2004 - 11:00 AM

As I believe the DVD's formats biggest weakness is subpar sound due to lossy audio codecs, I hope the content providers don't use this as an excuse to lower the audio bitrate on a disc in order to squeeze in more mundane DVD special features. Perhaps DD+ will be a good thing if the existing bit rate is kept the same, but the audio quality is improved. But I doubt if the content provider's see it that way. With Blue-Ray and HD-DVD coming, I really don't understand why lossy audio codecs need to be used at all for these future disc-based formats. Shouldn't there be enough disc capacity for full bitrate 5 channel 96/24 PCM sound?

#47 of 58 OFFLINE   Roger Dressler

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Posted April 23 2004 - 03:12 PM

>>Shouldn't there be enough disc capacity for full bitrate 5 channel 96/24 PCM sound?<< 5.1-ch 96/24 PCM uses 13.8 Mbps. It can fit. Content makers will indeed have this as an option.
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#48 of 58 OFFLINE   Roger J

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Posted April 23 2004 - 03:19 PM

Might have something to do with the millions of receivers and pre/pros out there that are already compatible with Dolby Digital. Virtually any audio format can be used as an option, and I'm sure there will be something like MLP included, but there has to be backward compatibility with all that hardware already out there and that means Dolby Digital.

#49 of 58 OFFLINE   Roger Dressler

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Posted April 24 2004 - 07:24 AM

>>there has to be backward compatibility with all that hardware already out there and that means Dolby Digital<< Excellent observation! Just so there's no confusion, it doesn't mean that the need to address this compatibility means the option for 96/24 PCM or MLP is in any way restricted.
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#50 of 58 OFFLINE   Richard Paul

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Posted April 24 2004 - 02:53 PM

Roger, thanks for the information and could you tell the maximum bit rate and highest number of channels that DD+ can support in the candidate ATSC standard.
This is actually why I see the HDMI interface as a great leap forward for a/v connections. When it becomes the standard connection it will make which audio or video codec used irrelevant to an A/V receiver. Since the audio and video over HDMI is sent in uncompressed form it will not restrict what codec can be used. Another advantage is that video consoles and computers could send out up to 7.1 channels of uncompressed audio instead of having to change it to a compressed form as is currently done for the X-box. Though HDMI was made mainly for copy protection it will help make future A/V receivers codec neutral, which I consider to be a very good development.

#51 of 58 OFFLINE   Roger J

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Posted April 24 2004 - 04:43 PM

How do you figure? Something has to turn that digital bitstream into separate analog channels somewhere.

#52 of 58 OFFLINE   Roger Dressler

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Posted April 24 2004 - 07:54 PM

Richard wrote: >>could you tell the maximum bit rate and highest number of channels that DD+ can support in the candidate ATSC standard<< ATSC Robust Channel has the same data rate max as the main channel: 448 kbps, and 5.1 channels. >>Since the audio and video over HDMI is sent in uncompressed form it will not restrict what codec can be used. Another advantage is that video consoles and computers could send out up to 7.1 channels of uncompressed audio instead of having to change it to a compressed form as is currently done for the X-box.<< HDMI certainly is a great step forward. Would have been a big help for DVD-A had it come 5 years sooner. And it doesn't care if the data is PCM or coded. One of the complications of decoding all the audio in the source unit occurs when one wants to instruct the audio to change, such as to turn on DRC, for example. Now the instructions that normally go to the AV receiver have to go to the source player/decoder. Kind of suggests rather than fatter pipes and 2-way communications we should just put the sources into the same box as the AV decoder.
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#53 of 58 OFFLINE   john_FE

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Posted April 27 2004 - 12:01 AM

Correct me If Im wrong but even If this format allows more discrete channels like 7.1, wouldnt the movie studios still have to pay to encode it as opposed to the 5.1 standard? I mean we have a 6.1 option but how many DvD's come out with that. I really think 5.1 has become the standard.

#54 of 58 OFFLINE   Dave Moritz

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Posted April 28 2004 - 03:33 PM

I think most of us would like to hear about the home side as much as the broadcast side. And besides not sure what almost no, but yes really means. Is there any chance that the subject will be covered soon regarding the decoding for home theater and what the specs will be. I realize that the specs do not tell it all but it helps to know what DD+ should be able to do. The only reason I did not respond right away is because I have been away from my computer lately. I would love to know how a processor with a previous codec can take full advantage of the new DD+ format? Wouldn't we need to have the updated processor with the new codec to truely take advantage of improvements and more channels? Will DD+ be the default surround for HD-DVD? Or will it be a combination of DD and DD+? Until DD+ can prove itself and provide a rich and transparent soundfield. I will continue to buy and prefere DTS soundtracks over DD! It is great that Dolby is working to continually improve its product and I hope there is a big diffence when DD+ is available. Time Will Tell! And as a side note how many people give SDDS another 2 years before it disapears? Sony obviously doesn't seem to be interested in keeping SDDS viable or updating it.

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#55 of 58 OFFLINE   Dave Moritz

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Posted April 28 2004 - 03:58 PM

While you are correct that Meridian still owns MLP. MLP is most likely the best format for audio today. While Dolby can realize that MLP that Meridian solved a critical problem. Dolby taking credit for recongnizing that MLP solved critical problems for dvd-a and helping in adopting it. Is like Meridian taking credit for DD being the primary digital format on dvd by helping persude the DVD Forum that DD was the logical choice. While it will be great to see MLP and what it can do for movies like it has done for multi channel audio. If both Dolby and DTS camps adopt MLP and use similar bit rates then the Dolby vs DTS contiversy may finally end, and become mute.

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#56 of 58 OFFLINE   Roger Dressler

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Posted April 28 2004 - 06:02 PM

Dave Moritz wrote: >>My system is good enough to be able to tell the difference between DD and DTS on most movies. It is not an assumtion and it is my opinion as well that matters to me as well. So the comment regarding assumptions is out line IMHO. And the differences I find are audible and not assumption!<< I would only comment that Dolby has consistently said that it is very easy to hear the differences on these various DVDs between the DD and DTS tracks. The changes in volume, bass, EQ, surround levels, are often quite easy to hear, other times more subtle. We wrote some papers documenting a few. Where this gets slippery is in ascribing these audible differences solely to the codecs that deliver these different renditions of the soundtracks. >>And besides not sure what almost no, but yes really means. Is there any chance that the subject will be covered soon regarding the decoding for home theater and what the specs will be.<< The lower bitrate efficiency improvements for mono to 5.1 DD+ broadcasts, for example, will be equally beneficial to all listeners, whether they have a DD or a DD+ decoder. This is the “no” part—-no, you don’t need a new decoder to take advantage of DD+. But if a DD+ signal delivers, say, 7.1 discrete signals, then yes, you will need a new decoder to take full advantage of that. Existing decoders will get the usual 5.1 mix. >>I would love to know how a processor with a previous codec can take full advantage of the new DD+ format? Wouldn't we need to have the updated processor with the new codec to truely take advantage of improvements and more channels?<< Not full advantage, as above. DD+ signals are easily converted back to standard DD format, but the process raises the bitrate. No one cares because it just goes over the S/PDIF link to the decoder. The broadcaster still gets the lower bitrate benefit. >>Will DD+ be the default surround for HD-DVD? Or will it be a combination of DD and DD+? << No one knows what the audio options will be until the HD formats are decided. It is all in discussion. >>Dolby taking credit for recongnizing that MLP solved critical problems for dvd-a and helping in adopting it. Is like Meridian taking credit for DD being the primary digital format on dvd by helping persude the DVD Forum that DD was the logical choice.<< I don’t follow. The fact is this, MLP might not be in DVD-A had Dolby not participated with Meridian. There were various other solutions on the table. >>If both Dolby and DTS camps adopt MLP and use similar bit rates then the Dolby vs DTS contiversy may finally end.<< Just to be clear, DTS cannot adopt MLP, but they, and others, can consider other lossless coding techniques.
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#57 of 58 OFFLINE   Lewis Besze

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Posted April 28 2004 - 06:29 PM

Sure you can it just not relevant,since you didn't compare them to the source.

#58 of 58 OFFLINE   Kevin C Brown

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Posted April 29 2004 - 06:13 PM

Good point. "Different" doesn't necessarily mean better or worse.
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