DD+ & True HD diiference not as noticeable as PCM 5.1?
03-02-07, 09:48 AM
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DD+ & True HD diiference not as noticeable as PCM 5.1?
I got the Denon 887 for my PS3 & the difference between the 5.1 track & the PCM 5.1 or DTS HD is extremely noticeable. First, they're much louder. And they also have much better quality. The PS3 shows bitrates & regular 5.1 is about 666kbps. DTS HD is 1.5Mbps & PCM is either 4.6 or 6.9Mbps depending on the disc. I just got my first True HD BluRay (NIN concert) & that fluctuates from the high 3s to the low 5s. That only had a stereo track as a secondary, so I couldn't direct compare with 5.1, but it sounded as good as the PCM. I just traded in my 360 HD & got the Toshiba A2 & so far from what I tried (Batman & Fear & Loathing), the difference between the Plus tracks & the True HD is barely noticable. Is this because the Plus track is at a higher bitrate than 5.1 (this player doesn't show bitrates, so I can't tell- does anyone have one that does show it?). Or is the True HD on HD-Dvd not as high as the BluRay version? I have the player output set to PCM, and the receiver seems to be showing it correctly, so I'm pretty sure it's playing it right. I was just hoping for a bigger difference. I also have to turn the volume up louder for HD-Dvds. I thought it was just because of the 360 downconverting the Plus to regular 5.1, but this player is also not as loud.
03-02-07, 10:02 AM
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Similar to DTS-HD, Dolby Digital Plus is 1.5Mbps. There are discs, however, where the Plus track is half that rate, which would be more or less equivalent to DTS tracks on standard DVDs. TrueHD and PCM 5.1 are quite the same in terms of quality, however, TrueHD does have the edge on efficiency.
03-02-07, 10:38 AM
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Once decoded, TrueHD is bit-for-bit identical to PCM. If the PCM tracks has a 0101, the TrueHD track has a 0101. It is impossible for the zeroes and ones on one track to be "better" than the zeroes and ones on the other.
03-02-07, 10:57 AM
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Originally Posted by Josh Z
Once decoded, TrueHD is bit-for-bit identical to PCM. If the PCM tracks has a 0101, the TrueHD track has a 0101. It is impossible for the zeroes and ones on one track to be "better" than the zeroes and ones on the other.
TrueHD has a variable bitrate, doesn't it? So the same ones and zeroes can all be packed into a tighter package than with constant bitrate PCM?
03-02-07, 01:09 PM
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Originally Posted by applesandrice
TrueHD has a variable bitrate, doesn't it? So the same ones and zeroes can all be packed into a tighter package than with constant bitrate PCM?
Yes, it has a variable bit rate. Amir from Microsoft explained this the most clearly. Say you have a movie with one hour of audio and one hour of absolute dead silence. An uncompressed track requires the same high bit rate regardless of the fact that there's no sound, thus wasting a ton of disc space. A lossless track saves that space by only encoding the actual audio.
03-02-07, 01:09 PM
#6
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Originally Posted by applesandrice
TrueHD has a variable bitrate, doesn't it? So the same ones and zeroes can all be packed into a tighter package than with constant bitrate PCM?
Edit: Josh Z beat me to it.
Last edited by Drexl; 03-02-07 at 02:53 PM.
03-02-07, 02:11 PM
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So, the answer is that the difference between the Plus track & the True HD isn't as great as 5.1 & PCM because the bitrate isn't that much higher? Because the DTS HD sound just about as good as PCM tracks & they're only about a third of the size. And I'd say that the 24bit (rather than 18, which most have) PCM tracks are better than True HD. They're 6.9Mbps the whole time (and yes I know it isn't needed the whole time) whereas the True HD stayed in the low 5s. Do you guys hear a huge difference between the Plus & True HD (no one answered that yet), or is it just me. Because like I said, the difference in regular DD & PCM or DTS HD is huge.
03-02-07, 02:28 PM
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There is no audible difference between TrueHD and PCM. If any difference could be heard, it could only be due to playback/processing on different pieces of equipment -- ie., what the player or receiver chooses to do with the signal. Or craziness. I guess that might explain somebody thinking they heard a difference.
03-02-07, 03:38 PM
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Difference between True HD & PCM? I didn't say anything about that. I also didn't ask why the bitrate is variable on True HD- that's just logic, the rate is lower when the music is quiter or just applause & goes up when it's louder & more instruments are playing, etc. It's the same as videos bitrate being almost 0 when the screen is blank & going up the more that's going on onscreen. The only question I'm asking, which no one has answered yet, is if I'm the only one who can't hear much difference between the DD Plus & TrueHD tracks on HD-Dvds. Because when I switch back & forth, I can't really hear any difference. While on BluRays, the difference is very easy to hear right away. And the BluRay I have with TrueHD sounds much better than the TrueHD on Batman Begins, which sounded pretty much the same as the DD Plus track.
03-02-07, 03:57 PM
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Originally Posted by El Kabong
Difference between True HD & PCM? I didn't say anything about that. I also didn't ask why the bitrate is variable on True HD- that's just logic, the rate is lower when the music is quiter or just applause & goes up when it's louder & more instruments are playing, etc.
The only question I'm asking, which no one has answered yet, is if I'm the only one who can't hear much difference between the DD Plus & TrueHD tracks on HD-Dvds. Because when I switch back & forth, I can't really hear any difference. While on BluRays, the difference is very easy to hear right away.
And the BluRay I have with TrueHD sounds much better than the TrueHD on Batman Begins, which sounded pretty much the same as the DD Plus track.
03-02-07, 04:03 PM
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Originally Posted by El Kabong
Difference between True HD & PCM? I didn't say anything about that. I also didn't ask why the bitrate is variable on True HD- that's just logic, the rate is lower when the music is quiter or just applause & goes up when it's louder & more instruments are playing, etc. It's the same as videos bitrate being almost 0 when the screen is blank & going up the more that's going on onscreen. The only question I'm asking, which no one has answered yet, is if I'm the only one who can't hear much difference between the DD Plus & TrueHD tracks on HD-Dvds. Because when I switch back & forth, I can't really hear any difference. While on BluRays, the difference is very easy to hear right away. And the BluRay I have with TrueHD sounds much better than the TrueHD on Batman Begins, which sounded pretty much the same as the DD Plus track.
Holy cow -- I'm sorry. I totally mis-read your earlier post! Honestly, I haven't done a lot of back-to-back comparissons between Plus and TrueHD, and from the little which I have done -- also with "Batman Begins" -- I can't really put my finger on a terribly compelling difference, but it did seem a bit more "open and airy". Whatever that means.
As for why Blu-Ray TrueHD sounds so much better than their DD tracks -- yes -- it is because, as you pointed out earlier, their DD tracks are lower in bitrate.
Also, regarding TrueHD on HD-DVD vs. TrueHD on Blu-Ray, they are the same -- bit for bit. The only differences you would hear would have to do with your equipment -- the A2 vs. the PS3 -- and a better comparisson would have to be between NIN HD-DVD and NIN Blu-Ray, instead of two different titles.
Anyhow, sorry I misunderstood earlier. Maybe I should just gracefully bow out of this discussion before I get myself into real trouble!
03-02-07, 04:26 PM
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Originally Posted by XavierMike
I thought I read on another post where Blu-ray's DD is equal in terms of bit rate just without the "+" in the name.
I read that, too, but I don't buy it. Blu-Ray's DD is at that 600-whatever bitrate which is essentially half the rate of a full DD+ track. There are of course DD+ tracks which have that cut rate -- I think "Slither" is one, for example -- but what Josh says above about transparency goes a long way toward making a whole lot of sense. Wait -- what am I doing posting again!! AACK!! Somebody get me a 12-step program!!
03-02-07, 05:25 PM
#15
It is equal at 640kbps, which is why people don't complain about the lack of the DD+ moniker on Warner titles anymore:
From Roger Dressler of Dolby Labs:
and regarding Universal's 1.5mbps DD+ tracks:
From Roger Dressler of Dolby Labs:
Due to the way HD DVD structures audio data in packets, the only way to offer advanced capabilities--higher quality sound and option for more channels--was to adopt a different codec than DD, which was locked at 5.1 and 448 kbps, same as DVD. DD+ was specifically designed to address HD DVD's structure--the DD+ coding frames become progressively shorter (from 6 to 3 or 2) to allow more of them to pass thru the framing structure in a given time, thereby raising the data thruput.
Blu-ray, on the other hand, has no such packet constraint. That allows DD to be used in its full 6-block frame for maximum coding efficiency (efficiency drops slightly as the frame size is reduced), and to use its full 640 kbps capability for the very first time on optical media, thereby bringing higher quality.
If you look at the DD+ structure when delivering a 7.1 program (someday), you will see a 2-frame pairing. The first frame is the usual complete 5.1 mix. The second frame has the new channels for the 7.1 mix. The second frame also has all the new metadata and channel management DD+ info needed to control the overall reconstruction process. This explanation is identical for HD DVD and BD. The only difference is that both frames in HD DVD are DD+ because they must have a shorter frame duration, whereas in BD the first frame is standard DD because it does not have to be shorter. Both frames in the BD pair are full 6-blocks, highest efficiency mode.
Furthermore, while HD DVD discs generally do not let you stream the DD+ to an output without going thru the mixer (and yes, the Toshiba player has the DD+ to DD640 converter, FWIW), BD does allow that option. So you have a chance to get the 640 DD stream right off the disc and into your AVR via S/PDIF. One might prefer that option to DD+ transcoded to DTS.
Given distinctly different circumstances, Dolby was able to adapt its coding technologies to bring improved quality and more channels to both formats. The goal was not to make the end results different, but the same in spite of the situation.
Blu-ray, on the other hand, has no such packet constraint. That allows DD to be used in its full 6-block frame for maximum coding efficiency (efficiency drops slightly as the frame size is reduced), and to use its full 640 kbps capability for the very first time on optical media, thereby bringing higher quality.
If you look at the DD+ structure when delivering a 7.1 program (someday), you will see a 2-frame pairing. The first frame is the usual complete 5.1 mix. The second frame has the new channels for the 7.1 mix. The second frame also has all the new metadata and channel management DD+ info needed to control the overall reconstruction process. This explanation is identical for HD DVD and BD. The only difference is that both frames in HD DVD are DD+ because they must have a shorter frame duration, whereas in BD the first frame is standard DD because it does not have to be shorter. Both frames in the BD pair are full 6-blocks, highest efficiency mode.
Furthermore, while HD DVD discs generally do not let you stream the DD+ to an output without going thru the mixer (and yes, the Toshiba player has the DD+ to DD640 converter, FWIW), BD does allow that option. So you have a chance to get the 640 DD stream right off the disc and into your AVR via S/PDIF. One might prefer that option to DD+ transcoded to DTS.
Given distinctly different circumstances, Dolby was able to adapt its coding technologies to bring improved quality and more channels to both formats. The goal was not to make the end results different, but the same in spite of the situation.
The same question can be asked for the 1.5 Mbps rate, but at least in that case there's ample room to grow for the 7.1 option, but after that, we're almost maxed out again. We thought it was cool that Universal matched our bitrate to DTS's. But that rate is not necessary to get the full benefit of DD+ for 5.1. It is indeed rapidly diminishing returns beyond 640 kbs.
03-02-07, 06:26 PM
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Alright. I thought there might be something wrong the Hd-Dvd player that I wasn't noticing it very much, but if it's the same as the DTS HD that would definitely explain it, since the difference between the DTS HD & PCM are also not that huge. And sorry applesandrice, I wasn't trying to be a jerk to you. Just a little frustrating when someone (wasn't you) posts something right at the top that's not really about your question then the whole thread goes off on that tangent. I just wanted some other ears' opinions, not really any specs that I already had- except for the DD+ rates.
03-03-07, 01:02 AM
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Originally Posted by El Kabong
Alright. I thought there might be something wrong the Hd-Dvd player that I wasn't noticing it very much, but if it's the same as the DTS HD that would definitely explain it, since the difference between the DTS HD & PCM are also not that huge. And sorry applesandrice, I wasn't trying to be a jerk to you. Just a little frustrating when someone (wasn't you) posts something right at the top that's not really about your question then the whole thread goes off on that tangent. I just wanted some other ears' opinions, not really any specs that I already had- except for the DD+ rates.
No sweat. Sorry I didn't read your posts carefully enough!
03-03-07, 10:20 AM
#18
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Seeing a lot of mention of DTS-HD, etc. Right now, the players are just outputting the core DTS (up to 1.5 Mbps). Once players and decoders are on the market that can handle the full capability of DTS-HD, then we can start doing some true head to head comparisons.
03-03-07, 01:07 PM
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Originally Posted by rexinnih
Seeing a lot of mention of DTS-HD, etc. Right now, the players are just outputting the core DTS (up to 1.5 Mbps). Once players and decoders are on the market that can handle the full capability of DTS-HD, then we can start doing some true head to head comparisons.
The PCM 010101011 versus the Dolby TrueHD 010101011 vs the DTS-HD 010101011?
03-03-07, 09:20 PM
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I'm pretty sure from all the reviews that I've read & from what I can hear that the PS3 does play the DTS-HD track. The difference in the Alien Predator sound when I got the new receiver was pretty impressive. All DvdTalk reviews say it's the only player that does right now. And Bus, what do you mean by the 0s & 1s? Are you saying that they all sound the same? so I guess on dvds, the DD5.1 & DTS tracks all sound the same too? Read any review & you'll find they don't. And those have very close bitrates. Why do you think it would be stupid to compare these? Why would they include multiple tracks if they're exactly the same?
03-03-07, 10:01 PM
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Originally Posted by El Kabong
And Bus, what do you mean by the 0s & 1s? Are you saying that they all sound the same? so I guess on dvds, the DD5.1 & DTS tracks all sound the same too? Read any review & you'll find they don't. And those have very close bitrates. Why do you think it would be stupid to compare these?
However, Dolby TrueHD and DTS-HD Master Audio are both lossless audio formats. They don't throw out any portion of the spectrum. They contain the exact same digital data present on the audio master. Lossless = no loss. You can't have one lossless format that's more lossless than another lossless format. If that were true, then they wouldn't be lossless at all, would they?
03-03-07, 10:02 PM
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Originally Posted by Josh Z
The answer to this should be obvious. Dolby Digital Plus (the base standard on HD DVD) comes closer to audible transparency with its master than standard Dolby Digital (the base standard on Blu-ray) does. Both formats also offer lossless or uncompressed tracks that are 100% transparent to their master. If you've got a DD+ track that's, say, 90% transparent, it's going to be damn difficult to tell that from TrueHD. Whereas a standard DD track that's more like 75% transparent will be much easier to tell apart.
03-03-07, 10:21 PM
#23
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Originally Posted by El Kabong
And Bus, what do you mean by the 0s & 1s? Are you saying that they all sound the same?
so I guess on dvds, the DD5.1 & DTS tracks all sound the same too?
[DD and DTS] have very close bitrates.
Why would they include multiple tracks if they're exactly the same?
As to why an individual disc would contain more that one of the three formats, it would be pretty much a waste of space. Are there any discs that actually contain two or more of the three formats?
03-03-07, 11:41 PM
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Originally Posted by Spiky
In addition to this, many of the HDDVD TrueHD tracks have not been high quality lossless. I'm guessing this is changing with competition from the PCM on BD, but I haven't looked it up.
03-04-07, 02:00 AM
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Originally Posted by Josh Z
TrueHD is losslessly compressed. Once decoded, it is identical to uncompressed PCM. Lossless = No loss.
Yes, it has a variable bit rate. Amir from Microsoft explained this the most clearly. Say you have a movie with one hour of audio and one hour of absolute dead silence. An uncompressed track requires the same high bit rate regardless of the fact that there's no sound, thus wasting a ton of disc space. A lossless track saves that space by only encoding the actual audio.
Yes, it has a variable bit rate. Amir from Microsoft explained this the most clearly. Say you have a movie with one hour of audio and one hour of absolute dead silence. An uncompressed track requires the same high bit rate regardless of the fact that there's no sound, thus wasting a ton of disc space. A lossless track saves that space by only encoding the actual audio.
I don't think an uncompressed soundtrack can ever be truly identical to a lossless track just because the nature of the thing. I guess we need some more examples to make sure that Dolby did their homework when designing the codec.