With BD, there is sufficient capacity for 5.1 LPCM or even higher, which is CD quality audio for 5.1 channels. My question is why is this worse than HD DVD and HD DTS? My Sony BDP-S1 can output LPCM to my older receiver which actually has 8 channel analog inputs (I wish I could use all of them).
Is it that LPCM is 48/16 and these new codecs are 96/24? From my understanding, 48/16 is very good and most of the issues with it were due to early mastering technology.
All modern films are mastered with 24/48 audio. Employees at these mastering facilities, as well as the individuals doing the theatrical mixes, have said as much on this forum. Even paidgeek has said as much over on the Industry Insiders forum.
Due to the high bandwidth and space requirements of uncompressed audio, most studios downconvert 24/48 master audio to lower 16/48 fidelity for use on Blu-ray disk. Only a handful
of current Blu-ray disks with LPCM feature master quality audio; more than 90% of all releases with LPCM feature inferior 16-bit audio. Paidgeek -- the representative from Sony Home Video -- has said several times over in the HDTV Software Media forum that Sony intends to stick with 24-bit -> 16-bit downconversion on LPCM releases for the forseeable future, due to bandwidth constraints.
Rather than downgrade the 24/48 master audio to lower 16/48 fidelity, some studios (FOX) have chosen to losslessly pack or "zip" these audio masters with DTS-HD MA or Dolby TrueHD. Once unpacked or "unzipped" by a player or future HDMI 1.3 receiver, the resulting output is a 24/48 LPCM track that is bit-for-bit identical to the original studio master.LPCM
2 hours @ 5.1 16/48 LPCM = 4.14 Gbytes @ 4.6 Mbps (used today by most Blu-ray disks with LPCM)
2 hours @ 7.1 16/48 LPCM = 5.52 Gbytes @ 6.13 Mbps
2 hours @ 5.1 24/48 LPCM = 6.21 Gbytes @ 6.9 Mbps
3 hours @ 5.1 24/48 LPCM = 9.32 Gbytes @ 6.9 Mbps
2 hours @ 7.1 24/48 LPCM = 8.28 Gbytes @ 9.2 Mbps
3 hours @ 7.1 24/48 LPCM = 12.42 Gbytes
@ 9.2 Mbps
2 hours @ 7.1 24/96 LPCM = 16.56 Gbytes @ 18.4 Mbps
3 hours @ 7.1 24/96 LPCM = 24.84 Gbytes @ 18.4 MbpsDolby TrueHD (comparable to DTS-HD MA)
2 hours @ 5.1 16/48 TrueHD = 1.26 Gbytes @ 1.4 Mbps ABR
2 hours @ 5.1 24/48 TrueHD = 3.06 Gbytes @ 3.4 Mbps ABR
3 hours @ 5.1 24/48 TrueHD = 4.59 Gbytes @ 3.4 Mbps ABR
2 hours @ 7.1 24/48 TrueHD = 4.23 Gbytes @ 4.7 Mbps ABR
3 hours @ 7.1 24/48 TrueHD = 6.35 Gbytes
@ 4.7 Mbps ABR
Both TrueHD and DTS-HD MA use variable bit rates, so the bit rate varies by the "complexity" of the soundtrack during the film. The ABR notation above refers to average bit rate.
If studios were to use BD50 exclusively for just the feature in AVC, audio in LPCM, and a few extras, this wouldn't be an issue. However, 80% of announced, upcoming Blu-ray titles use BD25, and more than two-thirds of the remainder slated for BD50 use MPEG-2. Moreover, studios are expected to add more and more extras to their disks. Later this year, we're expected to see the first Blu-ray releases with BD-Java and true PIP commentary, which will subtract additional bits from the available mux rate.
With BD25, you can forget 24/48 LPCM on all but the shortest movies. Even with BD50, LPCM at master quality 24/48 starts to eat into the picture quality when MPEG-2 is used. Subtract 7.1 24/48 from the available mux rate and you're left with with a bit over 45Mbps. Subtract the three foreign language tracks in 640Kbps Dolby Digital and you are left with 43Mbps and change. Subtract the picture-in-picture video commentary featured on upcoming BD-Java disks and you are left with 36-38Mbps. Subtract overhead and interactivity and you're left with 34-36Mbps. If all studios were to abandon MPEG-2 in favor of AVC, that would be fine for all but the longest movies, but that's not going to happen.
When less than 10% of announced Blu-ray titles feature the combination of BD50 and AVC, we need
the advanced audio codecs to get master quality, 24-bit / 48kHz audio.
Can anyone comment about whether HD DD and HD DTS sound better than LPCM?
Dolby TrueHD and DTS-HD MA are just lossless packing methods for LPCM. Said a different way, they are basically zip files containing LPCM. This lossless packing may be unnecessary on most BD50 disks with AVC video, but again, only a small minority of announced titles actually use both BD50 and AVC.
Examples of Blu-ray releases with 24/48 LPCM tracks include Chicago
, Pearl Harbor
, The Prestige
, and The Wild
. Except for The Wild
, all of these are BD50 releases, and three of them use AVC.
Even if all studios were to use the combination of BD50 and AVC, that might still prove inadequate for high-fidelity 24/48 LPCM audio on the longest films, particularly as studios add interactive disk features. Consider the film Dances with Wolves
. This has a run time of 226 minutes, which means that the average bit rate available for that title on BD50, assuming no extras
is approximately 29 Mbps.
Subtract 7.1 24/48 LPCM from that and you're left with with a bit under 20Mbps. Subtract the three foreign language tracks in 640Kbps Dolby Digital and you are left with 18Mbps and change. Throw in a picture-in-picture video commentary featured on upcoming BD-Java disks and you're left with 10-12Mbps ABR for video.
Does that sound good to you?
Other recent films of similar length include King Kong, The Green Mile, The Lord of the Rings: Return of the King, Spartacus, and Titanic, as well as classics such as Apocalypse Now, Ben Hur, Lawrence of Arabia, and Schindler's List.