First Blu-Ray titles not encoded with new audio codecs (1 Viewer)

[Craig W]

...

in addition less efficient MPEG2 and a 25-GB single-layer disc I believe will cause sacrifices to be made in the video quality.

Again, I really don't care who wins, but I think some are assuming that Blu-Ray is automatically better due to the higher hardware numbers that don't tell the whole story.

Peter, I am on your side in that I want the best quality possible. If Sony was using VC1 or H.264 right out of the gate I probably wouldn't be so vocal about the audio issue, but when you place the uncompressed audio on top of a 10-year-old compression technology I am not as enthusiastic about Blu-Ray as you currently.

If in another year or so Sony moves away from MPEG2, proves the 50-GB disc works and proves the thinner protection layer is reliable, then I will say its a better format.

Right now I don't think we have enough information to say either format is superior.

 

[JediFonger]

no one has answered me question yet. isn't PCM 44.1kHz/16-bit? isn't TrueHD=24-bit/96kHz or 24-bit/192kHz across all channels? aren't both uncompresssed anyway? in that case TrueHD would work.

 

[ChristopherDAC]

PCM is only 16-44.1 on CD and LaserDisc. On DVD it is sampled at 48 or 96 kHz, at 16, 20, or 24 bits ; on DVD-A it is possible to have 2 channels of 24 bit 192 kHz PCM ; and on Blu-Ray it may go up to 8 channels of 24-192. In any case the 44.1 kHz sampling rate, a relic of the days when digital audio recording was done on videotape, will not be an option. In any case, studio masters have been 24-48 or 24-96 for years now.

Also, TrueHD is "losslessly compressed", that is, packed like a ZIP file. When decompressed it is bit-for-bit identical to the uncompressed original. This has been stated several times already.

 

[DaViD Boulet]

Ok everyone,

Just stop! (not you ChrisDac )

There are a few facts mentioned in this thread but most of what's being tossed around is either just flat-out wrong or, in most cases, half-truthes that are very misleading.

I know this is *the* most confusing part of the new HD formats and even over at AVS with Roger from DD and other "experts" it's still often ambiguous.

I'll try to state the facts very simply (repeating what some others have already said...thanks!):

FACTS:

• 
  Initial BDs FROM SONY STUDIOS will not use DD+ , Dolby THD or DTS-HD. Instead they will use LPCM (16/48 so it seems) and will ALSO have a conventional DD or DTS soundtrack for legacy listeners without HDMI or analog inputs. Ok? Did everyone hear that? Lee? You get your DD or DTS like normal on BDs...it's not just LPCM on there.
  
  Warner will not be using LPCM--they'll use DD+ etc. just like on HD DVD.
  
  BD requires that a legacy-style DD or DTS signal be present for legacy lisenters so all LPCM titles will still have and provide a traditional DD or DTS signal. Even those legacy codecs will sound better than DVD because the DD will be at 640 and the DTS would be at 1500. Also, at least in the case of DD, it can be extracted by all BD players from any DD+ signal (so a DD+ signal on DVD does the job all by itself). This may also be true for DTS-HD but that hasn't been tested yet.
  
  
  LPCM provides the HIGHEST quality audio possible...it's just as good sounding as Dolby True HD, MLP, or DTS-HD in lossless mode. Why? Because all those codecs are doing is compression LPCM in bit-for-bit manner. Dolby True HD and DTS-HD lossless are just "zip files" for LPCM audio. LPCM is the unzipped file...and it's what you get back after unzipping the Dolby True HD/DTS-HD signal prior to d/a conversion.
  
  Make sense?
  
  So there's nothing "lesser" about Sony opting for LPCM in terms of sound quality. The only downside would be the data space tha raw LPCM requires which may push the limits of a 25gig BD. But if they can do it without sacrificing image quality, then there's no problem.
  
  The bummer is that the resolution will only be 16/48 on these initial titles. HOWEVER...it also happens to be 16/48 on the HD DVD titles using DD+ and Dolby True HD! So they are ABSOLUTELY NO BETTER SOUNDING than the LPCM on early BDs.
  
  Ideally, everyone would use at least 20/48 and preferrably 24/48 or 24/96.
  
  The reason that Sony's early BD titles are avoiding advanced codecs is because not all BD players can provide full-quality from advanced codecs, but they all can provide full quality from LPCM and all BD players (unlike HD DVD players) can provide the "core" DD stream from a DD+ signal via coax/optical output. HD DVD players are required to have decoders on board for DD+ and other codecs so that's why you're seeing them on HD DVD sooner. Expect decoders to become standard on BD players within a year and by that time you'll see DD+ etc. on BD as well.
  
  The packing method for DD+ on BD preserves a "core" DD stream at 640 datarate which can be extracted by *all BD players* and sent out via coax/optical output for conventional decoders. This is cool. It's also something that HD DVD player's can't do...they have to fully decode DD+ and then *recompress* it to DD or DTS for coax/optical output. See below.
  
  HD DVD players don't pack DD+ the same way, there is NO CORE DD COMPONENT to the DD+ on HD DVD. We've been through that on AVS and read the Dolby white paper...don't tell me I'm wrong because it's already been established this is really the case. This is why early Toshiba players are outputing DTS for legacy listeners via SPDIF instead of a DD "core" from DD+ soundtracks. Basically, the HD DVD player has to decode the entire DD+ stream to LPCM internally, and then *recompress it* on the fly with either a DD or a DTS encoder in real time. Turns out that DTS encoders were cheaper and easier to get so Toshiba picked that as the only option. Bizarre in a way, but it works and folks get sound for their legacy gear. The Toshiba on-board DTS encoders are running at full bit-rate of 1500.

Ok, that's all I can think of for now.

Bottom line:

LPCM on BD will sound JUST AS GOOD as Dolby true HD on HD DVD which is just a 'zip file' for LPCM.

By 6 months advanced codec decoders will show up in BD players and Sony will start to use other codecs for audio.

I should add that ONLY SONY is using LPCM for audio. Warner will probably use the same DD+ (etc.) codecs they are using on HD DVD. And on BD it will work more elegantly in that the "core" DD 640 data-rate signal will be sent right out the SPDIF for legacy listeners.

Wait for HDMI 1.3 and BD players with decoder chips if you want full DD+/DTS-HD from your Blu-ray player.

 

[PeterTHX]

DaViD...you just summed up the content of my last few posts (albiet more elegantly).

You can be my Barf (from Spaceballs) to my Lone Starr "When you're right, you're right. And you? You're always right!"

Spaceballs: a future Blu-ray exclusive I might add...

 

[JeremyErwin]

Meridian Lossless Packing is often described as being a "zip file" for audio, but pkzip, gnuzip, bzip2 etc are all notoriously bad at compressing audio.

if you're interested, the technical bits of mlp are described in this white paper.

 

[Larry Sutliff]

But David didn't mention the modified laptop!

 

[JediFonger]

jeremy,

audio compression is not the same as file compression. hopefully we all know that =).

 

[Tony Richardson]

Fact #1

Until we actually see a real player with real software to play on it, no one knows what BD will actually do. Just look at what happened to the PS3 player specs or the dual layer BD discs at launch! Need I say more.

If you trust Sony to actually do what they say they will do. Get help, you need to see a good head shrinker! Same goes for Toshiba or any other manufacturer out there with this new technology.

 

[DaViD Boulet]

Sony isn't setting the standard for BD. You don't need to trust them. Warner and other studios are waiting and have big Blu-ray plans (that don't involve MPEG2, for instance).

Neither format can be adequately judged "in practice" until we've had discs and players on the market for at least a year to see what features and mastering choices are being offered.

 

[JeremyErwin]

OK, I grabbed a sample song at random:

"Hold On, Hold On20062:43Neko Case"

filesize in bytes

wav: 28790876 (1413 kb/s)
apple lossless: 19783376 (970 kb/s)
flac: 19765057 (970 kb/s
gz: 27730867 (1361 kb/s)
bzip2: 27373795 (1344 kb/s)

all of these encoders are lossless, but some are more efficient at compressing audio than others. I'm still waiting for gnu to release a mlp compressor...

970 kb is unusually high. I suppose my random pick was serendipitous

 

[ChristopherDAC]

Audio data lacks the kinds of structural redundancies which the usual file-compression algorithms, such as the LZW, exploit. It has others, which can be exploited by other, specialised algorithms, which would be no good in compressing ordinary datafiles. Among other things, it's desirable to be able to extract the data in linear time sequence!

All of these lossless compression techniques, however, have their foundation in Shannon's entropy concept of information theory.

 

[JediFonger]

i don't what you're trying to prove. you take an original .wav file and "compress" it using mp3 and you can achieve a fraction of the original size. you use zip and it doesn't do anything except pack the i/o's closer together (hence they're of similar size). thus audio compression techniques/formats can't be compared to file compression techniques.

 

[DaViD Boulet]

YiFeng,

he's talking about *LOSSLESS* audio compression. In that sense, simple reduncy techniques commonly used for datafiles don't get you much savings...the zipped file might only be a fraction smaller than the original.

In order to get the larger compressed-file efficiency different approaches needed to be applied to auido data.

The MP3 compressed file that you mentioned was not a lossy-compressed format. It discards data.

Yes, you can just "zip" a wave file like an ordinary data file. No one is desputing that. but try it and see how much space-savings you really get doing that in comparison to the figures posted for the audio-oriented lossless compression algorithms. The space savings are too minimal to be a real benefit to a medium like HD DVD or BD.

Also as was mentioned... audio data "packing" algorithms (a better term than "compression" when talking about lossless IMO) need to be decoded on-the-fly in real time. You can't "zip" the whole movie soundtrack and then "unzip" it as a single file all at once...you need a different approach that allows packets to be zipped and unzipped in a manner that *both* gives you decent packing efficiency ratios *and* allows for instant expansion back to LPCM.

 

[Lew Crippen]

To add a bit to Dave’s comments on compression, basically compression techniques relay on discarding redundant (or repeating) bits (but keeping track of them and restoring the discarded bits when the file is expanded to its original size.

Clearly (or perhaps not, if you are not familiar with file structure at the bit level) different kinds of files are most efficiently compressed with different kinds of algorithms and techniques. An algorithm/technique that compresses a text file compactly may not be as efficient when used to compress an audio file.

Of course the issue of packing and unpacking a file as a whole (e.g. PKZip) is one that does not lend itself well to large files designed to be used on the fly (just as Dave points out).

 

[aidie.t]

I'm beginning to have doubts if it's worth investing in any of the hd formats most reviews have been average and going back and looking at some of my sd dvd's such as unforgiven and the fugitive special edition viewed on a pioneer 505xde plasma using a yamaha 2500 dvd player with the picture scaled to 1125 lines,picture quality is very good.Audio is excellent,i'm all for improvement in sound dts being my choice format but if hd/blu ray discs arent going to use new audio codecs why bother upgrading,considering all the negatives i've read it's putting me off either format and wanting me to cancel my pre ordered blu ray titles

 

[JediFonger]

interesting we're all talking about "lossless" when in a philosophical sense, a recording of *any kind* even analogue, is "lossy" because it isn't heard live . ok, i'll stop there, lol =).

 

[ChristopherDAC]

So where have you been pre-ordering Blu-Ray titles?

In any case, I don't understand not wanting them just because they're going to use uncompressed PCM audio instead of a compressed format, no matter how advanced.

 

[DaViD Boulet]

Chris Dac is correct.

The LPCM on the BD titles is as good as Dolby True HD or DTS-HD... which are merely "zipped" LPCM signals (short story explanation).

The *real* problem, as long as the bit-space allows for LPCM etc. without compromise of the image quality, is that the LPCM is only being done at the 16/48 resolution. But then again... the Dolby True HD and DD+ resolution on the first batch of HD DVDs is *also* only 16/48! So the Sony BD titles *still* are just as good.

The real adantage of lossless advanced codecs are:

1. Use less space/bandwidth than LPCM if space is at a premium.

2. provide (in the case of DTS-HD) for backwards compatibility with non-HDMI users by the presence of a "DTS core" stream in the same signal.

other than that... 16/48 is 16/48... whether LPCM or lossless packing!



Very, very true. One reason why it pisses me off that the early titles are all only 16/48... just *barely* better than CD audio. Give me 20/48 at the minumum guys!

 

[Edwin-S]

So early audio tracks are going to be 16 bits? Wow, even my 12 year old Yamaha CD player was 20 bit/48Khz. These new formats, with all that space, are starting out with a bit structure and sampling rate that is no better than a 12 year old CD player? Doesn't seem like an auspicious start for either format.