Is DD Plus better than DTS ES?

Discussion in 'Blu-ray & DVD Players & Recorders' started by AngelEyes, Apr 19, 2007.

  1. AngelEyes

    AngelEyes
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    Hi Chaps,

    I wonder if anyone would be kind enough to explain the difference in bitrate between the lower res HD sound formats (DD Plus) and a good DTS soundtrack for instance?

    I am annoyed to see so many HD DVD disks with 'only' a DD Plus soundtrack. With a 42" Fuji Plasma the increased screen res is nice but not noticeably better than Sky HD but the sound on an uncompressed source IS a lot better and I am more inclined to buy into a format when the sound is as good as the PQ.

    Adam

    EDIT: I also forgot to ask whether there is any difference between PCM 7.1 and DD HD or DTS HD? ...and more importantly do all work via analogue connections? So many sound formats now, my poor brain :)
     
  2. Ian_S

    Ian_S
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    It's a tough call this one...

    Having only heard DD+ through the crippled 360 Xbox player software, even normal DVD's sound better... :(

    My personal opinion is as follows. Normal DD and DD+ at 640kbps, along with normal DTS at 768kbps are indistinguishable. DD+ and normal DTS at 1.5mpbs are a step up over the previous ones, but again you'd be hard pressed to choose between them. I've not heard DTS-HD HR at 3.0mpbs, and there aren't any discs yet with DD+ that exceed 1.5mbps.

    At rates higher than 1.5mbps on film, IMO you might as well go DTS-HD MA or TrueHD. With average compression on films being quoted as 4:1, (PCM uncompressed for 5.1 and 16bit 48Khz is 4.6mbps) the use of say 3.0mbps as a fixed rate (lossless is variable) would seem an odd choice as it would take more space having a constant compression ratio of less than 2:1.

    So I agree, for films, I really would like to see more use of lossless codecs, in theory providing they're TrueHD or DTS-HD MA, then they shouldn't use much more space than a 1.5mbps track on average...

    For music related content the numbers jump higher much more quickly, but again, we ought to have capacity for lossless audio. BD for example can support 24-bit, 192kHz in 5.1 channels... 96Khz if you want 7.1.

    Oh for a re-release of Pulse on an HD format, compression artifact free SD picture and lossless high resolution 5.1 audio... :lease:

    The only difference between TrueHD, DTS-HD MA and PCM that I am aware of is that TrueHD still applies dialog normalisation as part of the decoding so does play around with volume. DTS-HD MA and PCM do not. This is a choice of the content author and apparently Sony are going to provide some releases with it turned off to see how people like it. Players on both formats HAVE to be able to handle 5.1 PCM. After that it gets more optional. But, as long as a player has a TrueHD or DTS-HD MA decoder built in, then you should get either PCM over HDMI at full decoded resolution or full output over analogue outs if the player has them.

    For HD-DVD, the Toshiba HD-E1 has only 2ch analogue outs, but will output full resolution decoded PCM over HDMI, the XE1 adds 5.1 analogue outs and both decode 5.1 TrueHD but NOT anything other than std 1.5mbps DTS. The Xbox 360 only has 2ch analogue outs and std optical digital out. It decodes DD+ (badly) and TrueHD 5.1 and outputs currently as normal DD over optical, or 2ch downconvert. An upgrade is expected that fixes DD+ decoding and adds a conversion to DTS option over optical.

    On BD, the Samsung only handles PCM lossless in 5.1 and normal DD and DTS. The PS3 adds TrueHD decoding but will only output it as PCM over HDMI, no analogue outs. The Panasonic (with v2.0 firmware) now supports, 7.1 DD+, 7.1 TrueHD and 7.1 DTS-HD HR (which is high resolution up to 6.0mpbs not lossless) and outputs over HDMI as full resolution PCM or over 7.1 analogue outputs...

    HTH...
     
  3. AngelEyes

    AngelEyes
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    Hi Ian,

    Thanks for that comprehensive reply.

    I am currently using an HTPC for playback with PowerDVD 7.3 and an X-FI soundcard via 7.1 analogue to my Rotel Processor.

    I currently have the X-FI set to 'Dolby Digital/DTS Bitstream Out' should I hav this set to 'Built in Decoder' as I assume my Processor won't be able to decode TrueHD? (Although I think it can handle PCM...?)

    A couple of titles have either DDTrueHD or PCM 5.1 or 7.1, will I get maximum available audio resolution to my processor using this setup or does it not work that way?

    Thanks,

    Adam
     
  4. Ian_S

    Ian_S
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    Oh god.... PowerDVD Ultra 7.3 and sound... :eek:

    That complicates things no end. I'm well and truly struggling with that combination myself and Vista has made it much worse!!

    As I understand it, the X-Fi 'built in decoder' option determines simply whether the X-Fi does the DD/DTS decoding or whether it simply passes it through to an external processor over the SPDIF out... Apparently the X-Fi decoder is supposed to be very good. However, the X-Fi won't decode TrueHD or any DTS-HD variant. I'm guessing it's already doing a PCM to analogue conversion.

    It's the PowerDVD software that does the TrueHD and DTS-HD decoding and according to the 'show information' option on my copy, it decodes DTS-HD Master Audio at full variable bit-rate and not just at core 1.5mbps... Which might just make PowerDVD the only DTS-HD Master Audio decoder available to the public. Presumably PowerDVD then just pumps the decoded stream digitally at the X-Fi card (or whatever is installed) to do the multi-channel D/A conversion...

    I say presumably because under Vista I cannot get PowerDVD to control the SPDIF output exclusively and get DTS out over optical. Everything gets re-mangled to DD at 640kbps by Vista... So I can't switch between core DTS and whatever PowerDVD is throwing at the multi-channel analogue outputs to compare the sound and see if PowerDVD really IS doing DTS-HD MA decoding. Also PowerDVD on my system creates loads of loud pops and crackles whenever it attempts to mix in menu sounds etc on discs... sounds terrible. However, once you're watching a film it sounds pretty good. It's just not quite all working together very well just now. Of course this could simply be a Vista issue and it may all work better on XP... only having Vista I couldn't tell.
     
  5. AngelEyes

    AngelEyes
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    The more I hear about Vista the more I am inclined to wait for SP2 or 3 lol

    My only problem is that the X-FI picks up interference from my gfx card (no they have seperate IRQ settings) and buzzes and hums all the time.

    Maybe this is a ground loop problem because it is faint on digital coaxial but much louder on analogue connections. It also occurs whether the HTPC is the selected source or not :mad:

    Anyway I digress...

    I listened very briefly to ghost in the Shell II inocence and the sound was very noticabley better listening to the PCM track so my guess is that works ok but I haven't tried and TrueHD or DTS HD tracks as I haven't got any.
     
  6. TrevorS

    TrevorS
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    FWIW -- I prefer DD+ to SD DVD DD5.1 (448Kbps). I think SD DVD half bitrate DTS (768Kbps) beats DD+ at 640Kbps. I consider SD DVD full bitrate DTS (1.5Mbps) to be equivalent to DD+ at 1.5Mbps. All the advanced Dolby tracks are available over S/PDIF if the player supports DD+/DD-THD crosscode to DTS.
     
  7. richard plumb

    richard plumb
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    I thought the different DD flavours only differed on bitrate? I.e DD+ at 448k would be the same quality as DD at 448k. The '+' is just to allow for larger packets on the HD formats, and also extensions for 7.1 etc.
     
  8. AngelEyes

    AngelEyes
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    Can you explain this please? Are you implying if the HTPC software supports uncompressed audio it can be sent to the processor via S/PDIF without any bitrate loss?

    Thanks,

    Adam
     
  9. TrevorS

    TrevorS
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    I haven't heard of a 448Kbps DD+. From what I've read, the bottom DD+ standard bitrate is 640Kbps (HD DVD), and the top DD standard bitrate is 448Kbps (SD DVD).

    I'm no CODEC expert, but at the very least, DD-THD is heavily different from DD+ and DD core -- DD-THD is fundamentally MLP. I've no idea on the degree of commonality or difference between the core DD and DD+ CODECs -- only that they have different bitrate standards.
     
  10. TrevorS

    TrevorS
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    I didn't mean to imply that. S/PDIF digital audio communications is considered a legacy format and standard CE players, receivers, and processors treat it according to the legacy standards. They allow for 640Kbps DD, 1.536Mbps DTS, and 1.536Mbps Dual Channel PCM (don't know the MPEG1 audio spec).

    All I'm saying is that some HD players support crosscoding of certain Advanced Audio streams to legacy DTS for S/PDIF output. If it wasn't legacy DTS, then it wouldn't be compatible with normal consumer home theater equipment.

    Specifically, the A1, XA1, A2, E1, A20 and E10 support crosscoding of DD+ and DD-TrueHD to max bitrate legacy DTS via S/PDIF. The XA2, XE1 and XBOX 360 add-on drive are supposed to be picking up this ability as well -- though I believe it will be selectable with those models.
     
  11. Geoff_D

    Geoff_D
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    Most of the DD+ tracks I've heard are at 1.5mbps and they sound superb. Regular DVD audio tracks, even 768kbps DTS, sound thin in comparison. Only the richness of full-rate DTS can better DD+. TrueHD sounds better than both, of course. :D
     
  12. Ian_S

    Ian_S
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    DD+ actually had most work done on it to be much better at very low bitrates for use in broadcast situations. I believe Dolby stated that it was pretty much the same at the 640kbps mark, but used very different algorithms as the bitrate reduces. (King King Europe edition HD-DVD for example has foreign language DD+ tracks at 384kbps)

    Normal DD wasn't really an option on HD-DVD as you cannot use 640kbps on it, much like you can't on DVD. So DD+ has enhancements for low bitrate broadcast and also gives Dolby a competitor to DTS in the high quality lossy stakes.
     
  13. TrevorS

    TrevorS
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    Thanks Ian,

    Dolby Labs used to have a very interesting white paper description of their DD CODEC on their website, but it seems they pulled it in favor of marketing verbiage :(. As you probably know, the early SD DVD DD5.1 bitrate was also 384Kbps, though I noticed that within about a year the studios recognized 448Kbps made a worthwhile improvement and made the change (they ignored the sadly lacking 2.0 stereo and Prologic tracks unfortunately :().

    Actually, one can legally use 640Kbps DD on SD DVD, however it is a non-standard track -- therefore, the SD DVD must also have a standard track included. An example of this is Pink Floyd's Pulse Concert SD DVD which augments the standard 448Kbps DD5.1 with a 640Kbps version. I haven't run across any other titles like this, but there may be some.

    That could be the inverse situation to using 384Kbps language tracks on an HD DVD. That is, are the 384Kbps tracks within the standard, or is it just the primary track/s that meet the standards requirements? Guess I'll have to find a copy of the HD DVD specifications to answer that one.

    That's interesting that Dolby would spec DD+ for broadcast at levels as low as 384Kbps -- makes me wonder why they bothered unless to add either more channels or more marketing flair :)! I'm going to guess flair (at last as the primary reason) :)!
     
  14. Ian_S

    Ian_S
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    Actually anything on DVD over 448kbps or HD-DVD over 509kbps (I think) is out of spec for each format due to the way packets are created on each physical format. Blu-ray is actually the first optical format capable of coding DD at 640kbps within spec. This is why Pulse doesn't play on quite a few players. Conversely, all DD receivers have to handle 640kbps to gain the logo...

    So, for HD-DVD, they needed something to go beyond DD, so DD+ was born and they also added support fot 7.1 channels too. Although the spec on HD-DVD allows for up to 3.0mbps I believe, it's likely no-one will go above 1.5 so that if they do use 7.1, they can claim a corresponding increase in bandwidth. Besides after that for movies you may as well go to TrueHD.

    BD didn't need DD+ as much, they decided that DD at 640kbps and DTS at up to 1.5mbps was sufficient and also compatible with more existing kit. HD-DVD simply didn't have that luxury and had to go DD+ or else be accused of not delivering anything better than DVD with DD.

    As it happens, HD-DVD get given the Kudos for a next gen "+" codec which really isn't that next gen and doesn't work with any existing kit in digital form. BD get slammed even though there's no difference between DD and DD+ at Warners favourite bitrate and 1.5mbps DTS has always been excellent. So good that Toshiba's players use it for all their output over legacy digital... :)
     
  15. TrevorS

    TrevorS
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    Some interesting numbers and perspectives :)!

    I was presuming 640Kbps DD would be legal on both HD video disc formats -- apparently not. Though as you say, HD DVD's choice of DD+ obviates the need -- a successful marketing gambit ("HD Audio Format") that side-steps a technical complication :).

    One note: Although DD+ is not supported by HDMI bitstream by existing kit (most of which doesn't support HDMI audio either), the crosscode to DTS via S/PDIF does solve that problem very nicely. People are frequently surprised to discover how good HD DVD sounds via S/PDIF -- as in VERY good.

    I agree that 1.5Mbps DTS (even LD's 1.2Mbps DTS) works exceedingly well. No question that lossless is inherently unbeatable, but I honestly feel 1.5Mbps DTS is very nearly there (and for most movie soundtracks, near-enough qualifies as there). However, as you mentioned earlier -- music/concert releases certainly deserve the lossless treatment. :)
     
  16. Ian_S

    Ian_S
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    Don't forget though that that DTS crosscode is not in the HD-DVD spec and was entirely Toshiba's idea for which IMO they deserve a lot of credit. MS may eventually copy them somewhen:rolleyes: for the 360 as a result.

    Somewhat interestingly though the XA2 and XE1 only crosscode to normal 640kps Dolby Digital which surprises me. Evidence of cost cutting? Is the DTS encoder that expensive?
     
  17. TrevorS

    TrevorS
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    I agree, that was smart (and clever) thinking on Toshiba's part. It's also very consistent with their providing the buyer the best immediate experience of the new format (without having to replace equipment). It fits in well with their effort to provide a very respectable upscaling performance for the buyer's existing SD library.

    Before I started following the A1 and XA1 threads on AVSforum las April, I had never heard of such a transformation from advanced CODECs to DTS, though, I'd never heard of DD+ and DD-THD either :). When I first installed my G1 player, I used Toslink for near four months and then a problem with my old AV processor prompted my purchase of an HDMI capable receiver as an approximate plug-in replacement. The old processor has excellent DTS playback and the S/PDIF (heavily jitter filtered) sounded really great. (Unfortunately, the old processor developed a noisy center channel output :(.)

    There was an intention imparted by Toshiba reps to a very reliable "insider" retailer (AVSforum) to provide a DTS crosscode option for the XA2. It's currently expected to show sometime this summer, though of course, there's never a guarantee with this kind of thing. However, if the XA2 gets it, I'm sure the XE1 will as well. From what Amir has said, it seems probable the option will be in place for X-BOX 360 very soon -- together with the solution to the compressed DD dynamics issue. Here's hoping. :)
     
  18. Quickbeam

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    Note that there is no difference in sound quality between DD and DD+ at 640kbps.

    DD+ is necessary on HD-DVD in order to allow higher bitrates than 448kbps and additional discrete sound channels; otherwise it's the same codec as DD.
     
  19. Smurfin

    Smurfin
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    Why do people just assume the higher bitrate = better quality? Trevor, if you can clearly hear an improvement between 640kbps DD and 768kbps DTS then you must have 24carat golden ears!

    Marginally better bit-rate doesn't necessarily mean marginally better sound, especially when comparing 2 different codecs.

    That said, if you can cite an example then I'll happily compare :thumbsup:
     
  20. TrevorS

    TrevorS
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    You are responding as though I made an absolute declaration that the one is superior to the other. I didn't, I limited it specifically to what "I think". You are welcome to think otherwise -- I've no objection!

    PS. For that matter, I've read many strong statements that DTS at any bitrate sounds no better than DD at 448Kbps. Whatever lights one's fire, I guess!
     
  21. Smurfin

    Smurfin
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    Trevor, that wasn't meant to be arsey, I just don't believe you can tell the difference. What discs have you compared? Let me know and I'll stand to be corrected :thumbsup:
     
  22. TrevorS

    TrevorS
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    I'm not interested in "correcting" anyone -- in fact, I'm not even interested in discussing it. It's pretty safe to presume your equipment is very different from mine and probably the tuning of our hearing is different as well (what I listen for Vs what you listen for). And suppose we disagree, all it would prove is that we disagree! Thanks, but no thanks! Have a good day :)!
     
  23. Smurfin

    Smurfin
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    Well personally I'm open to having my mind changed and my point of view "corrected", part of the fun of this for me is learning about AV.

    I listen for detail, dynamics, placement, separation. What do you listen for? :confused:

    Of course that's your opinion, I was asking you to qualify it, that's what debate and discussions are for, like I said I didn't mean my initial comment as arsey as it sounded :)

    However, as you've taken serious umbridge to me asking where your experience has been formed from, I take it that you've not actually compared anything and can't qualify it. Nuff said.
     

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