[FrantzM]

Hi


A new thread. I am an audiophile. I am very deceived by the sound quality of Dolby AC-3. I understand that there was a need for low bandwidth encoding in 1993. but we are in 2003 and there exist technology able to provide multimegabit/s enough to have bluebook CD quality on all 5 channels... AC-3 is so far behind CD it is laughable. Please conduct that experience. Listen to anything on the soundtrack of a movie without the picture...


We must acknowledge that HT has opened up a new era in music reproduction.

It is now easier and more affordable to reproduce true bass in the home.

The flexibility of new Processors and receivers in term of calibration begs the transfer of such flexibility to the audiophile world. I know we will be reluctant but so were we for CD and with good reasons see how much CD have advanced and now we have 24/96 and the technology exist for 24/192 !! We are still lumbering around with 320 Kbps or may be slightly more for Dolby AC-3. Aren't we being cheated? In term of fidelity and musicality to my ears AC-3 is not far from MP-3. Shouldn't we ask for more?


Your opinions as usual will be much appreciated.



Frantz

Port-au-Prince, Haiti

 

[tpigeon2003]

All I can say to this is I hope HD-DVD comes out with SACD quality audio and 1080p video. HD-DVD has a real opportunity to set the standard for both video and audio quality. If this does happen, I think it would mean the end of the cd as the value proposition is not there.

 

[Savageone79]

I think if anything it would be DVD-A quality audio.. not sacd. Having said that I am not sure that is even likely.

 

[tpigeon2003]

Savage

Quit ruining my day

 

[Don O’Brien]

The other side of this coin is the quality available with advances in perceptual encoding that have occurred in the last 10 years. The 4.7 GB storage limit of the single layer DVD was an enormous advance in optical storage, but we needed a second layer for extras and longer movies, multiple ARs, multiple soundtracks etc.

You will need enormous storage to run the bit rate on each of 6-7 channels to 1440k and accomodate the current ATSC bandwidth at 19.3 MB/s for 1080i hdtv.

 

[John Kotches]

Frantz,


Obviously you haven't thought through the ramifications.


Lossy codecs are REQUIRED when running full motion video on DVD simply because we're dealing with a finite bandwidth medium.


Assuming we were going with "just" stereo 24/96K, we're dealing with about 4.7 of the available 9.6Mb/sec for audio. This leaves about 2.5-3.5Mb/sec for encoding full motion video which means terrible (and I do mean terrible) picture quality.


Changing over to DTS (full bit rate) improves the availibility for picture, while utlizing 1.5Mb/sec for audio.


DTS (Half bit rate) utilizes 768Kb/sec, and is the prevailing DTS encoding for DVDs.


I have seen DD be anywhere from 192Kb/sec to 448Kb/sec.


If you are after "audiophile" quality and video simultaneously you will have to wait awhile. I'm not sure that HD-DVD has provisions for lossless audio compression schemes included with video or not. I haven't seen the final specs.


If you want audiophile quality now, you have to use DVD-Audio or SACD and forgo video.



Regards,

 

[Savageone79]

Actually I think he knows that.. I think he was refereing to an ideal format or if HD DVD comes out how it should be done. I think that more space should be allotted to audio so that we can have fullbitrate dts all the time or maybe even newer codecs like DTS 96/24 but I am not sure that DVD-A quality is possible since that would take up to much space even on an HD DVD. Sorry tpigeon2003 if i ruined your day but I actually prefer DVD-A sound over sacd myself (but i do enjoy both). Are many movie soundtracks even recorded at a high enough quality that they would take advantage of Hi res sound? I would imagine that most newer 5.1 movies are mastered only in CD quality since they know that is the only way it will be shown.

 

[John Kotches]

Savageone:


The original post is not clear with respect to the audio requirements for DVD-Video or a future HD DVD.


Given sufficient aggregate bandwidth (on the order of 30Mbits/second) it is possible to allow for the inclusion of MLP encoded (PCM) or DST encoded (DSD/SACD) material without deleterious effects to the video quality.


Keep in mind that HDTV is broadcast at a fixed MPG rate of 19Mb/sec (including 384 or 448K Dolby Digital). Upping the data rate to 30Mb/second should allow for the possibility of inclusion of these tracks.


As far as production values are concerned, the norm for studios is 20 to 24bit /48K. I don't know what the costs would be to change over to 24/96K but am certain it would be cheaper than DSD/SACD.


I have to agree with Don in that both encoder and decoder performance have been improving over time for the lossy codecs.


Regards,

 

[hongcho]

Just for fun...


192kHz, 24bit audio, uncompressed PCM... 24 x 192,000 = 4,608,000 bits/sec/channel.


But we are not talking about uncompressed PCM...


SACD's DSD ( http://www.disctronics.co.uk/technol...vdaud_comp.htm )... 2.8224 Megabits/sec/channel.


With 6 channels... 16.9344 Megabits/sec.


But uses DST to cut it roughly by half... 8.4672 Megabits/sec.


ATSC max bandwidth for a channel... ~19 Megabits/sec


But this also includes the audio bitstreams. But then again, the video quality _can_ improve with a bit more bandwidth and the compressed audio's bandwidth is small, let's just take the whole thing and give it to the video.


Then together it's roughly... 28 Megabits/sec = 3.5 Megabytes/sec (I think Firewire can easily handle this).


For two hours? 3.5 Megabytes/sec x 3600 sec/hr x 2 hr ~ 25 Gigabytes.


I don't know how big the capacity of HD-DVDs or Blu-Ray's, though.


The devices will definitely be too expensive for a general consumer market, but it seems feasible. No?


Just my $.02.


Hong.

 

[John Kotches]

hongcho,


For DVD-A, it would be 6 channels at 24bit/96K, which is roughly the same as SACD for 6 channels.


Compressed with MLP, typical bit rates are 5-6Mbit/sec -- with peaks at the maximum bit rate allowed by the DVD spec.


I suspect (but do not know for sure) that MLP has a fixed bit rate option. Others who know more about MLP would be better able to fill you in on this potential aspect of the MLP encoder.


It is far easier to deal with fixed bit rate audio than it is variable bit rate audio when having to reassemble tracks for A/V in a player.


Multi-channel High Resolution PCM (aka DVD-Audio) is presently easier to deal with in processors/receivers. All of the processing infrastructure (DSP horsepower) is centered on PCM operations for the moment, and until that changes, I would expect that PCM would be the encoding format of choice.


Just my opinion of course.


Regards,

 

[John Kotches]

As far as "firewire handling it", this is true -- but something somewhere MUST do the MPEG decode in your scenario.


Frankly, I think it is better being accomplished in either the player itself or in a scaler, but that too is just my opinion.


Regards,

 

[Savageone79]

That 19.3mb/s data rate for HD is not enough if anyone has watched most of it.. it starts to block up on fast moving scenes. If you are going to make an HD DVD standard it would be good to allow 25-30mb/s just for the video alone to make sure to get upmost PQ. I think the 96/24 DTS codec they use could be a valid comprimise between sound quality and compression.

 

[Dougofthenorth]

RE: "I don't know how big the capacity of HD-DVDs or Blu-Ray's, though.

&

The devices will definitely be too expensive for a general consumer market, but it seems feasible. No? "


I came across a I-net article that Linn is developing a player for "Blu-Ray" Nuon, the various size disks will have 14 gigs, 19 gigs & 24.7 gigs storage.


Price is rumoured around $9K US. Projected time is 5 years until it is used in prerecorded "DVD" sales.

It should be here in 1-2 years for commercial use & another year after that for home recording use.

 

[Dougofthenorth]

RE: "I don't know how big the capacity of HD-DVDs or Blu-Ray's, though.


The devices will definitely be too expensive for a general consumer market, but it seems feasible. No?


Linn has developed one, disc capacities are aproximately 14gigs, 19gigs & 24.7gigs. Price is around $9K US.


Timelines: Professional/commercial use ~1yr, Consumer ~2-3 yrs, Prerecorded movies ~5yrs.