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http://we.pcinlife.com/redirect.php?tid=1259597&goto=lastpost9 @9 [$ [0 Y5 o7 K. w3 e. u( m
http://www.anandtech.com/video/showdoc.aspx?i=3643&p=10
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2 [5 }2 g. Z( O. c3 MThe Race is Over: 8-channel LPCM, TrueHD & DTS-HD MA Bitstreaming
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It's now been over a year since I first explained the horrible state of Blu-ra
0 ^! d$ `# |& W% G( _' jy audio on the PC. I'm not talking about music discs, but rather the audio com
; ], ?3 H: P. ^# u6 o& o8 Fponent of any Blu-ray movie. It boils down to this: without an expensive sound2 j+ f$ b1 o, D3 W
card it's impossible to send compressed Dolby TrueHD or DTS-HD Master Audio s1 B5 m8 T+ H6 |- b1 A9 O% B2 I
treams from your HTPC to an AV receiver or pre-processor. Thankfully AMD, Inte
6 ^4 {: S9 |) L/ w- _l and later NVIDIA gave us a stopgap solution that allowed HTPCs, when equippe
: ]" U# g- g* m u, ud with the right IGP/GPU, to decode those high-definition audio streams and se* `3 E8 A+ _9 d5 h
nd them uncompressed over HDMI. The feature is commonly known as 8-channel LPC* Q% M! C7 _) e) S4 s0 n1 g
M support and without it all high end HTPC users would be forced into spending6 h4 k7 w; H0 A4 H
another $150 - $250 on a sound card like the Auzentech HomeTheater HD I just
5 X8 L3 H; |; `2 S4 crecently reviewed. 0 K: L/ e2 K/ f9 R+ `
( `% ]( P9 ?( I- Q: X9 xFor a while I'd heard that ATI was dropping 8-channel LPCM support from RV870 0 y1 O7 p- v( _
because of cost issues. Thankfully, those rumors turned out to be completely u3 a7 ^( f. X; t8 j
ntrue. Not only does the Radeon HD 5870 support 8-channel LPCM output over HDM. V+ E3 N$ P% L+ w) A) ?
I like its predecessor, but it can now also bitstream Dolby TrueHD and DTS-HD
' U% L4 F+ [7 A8 B) lMA. It is the first and only video card to be able to do this, but I expect ot
3 h5 q& N( y. t. O% p. N9 Ehers to follow over the next year. & Y; ~8 J& [, r) N* D; h
; {* O) Y; d( B! @+ l1 j- ?5 AThe Radeon HD 5870 is first and foremost a card for gamers, so unless you're b
, Q( B# l* K0 Yuilding a dual-purpose HTPC, this isn't the one you're going to want to use. I- Y# n% l* D2 N1 C7 u0 S
f you can wait, the smaller derivatives of the RV870 core will also have bitst
( l4 L" w8 A; F0 x9 kreaming support for TrueHD/DTS-HD MA. If you can't and have a deep enough HTPC1 L5 I; {8 U/ U* O6 G } B/ F
case, the 5870 will work. # |5 y4 Q8 f) r- a
6 K3 }% {4 x* }8 u+ v% S% B9 oIn addition to full bitstreaming support, the 5870 also features ATI's UVD2 (U- C- Q% `0 H+ c0 Q9 U+ T7 L
niversal Video Decoder). The engine allows for complete hardware offload of al
: o6 X4 | Y: j4 h0 i/ |) Nl H.264, MPEG-2 and VC1 decoding. There haven't been many changes to the UVD2
7 X- s! b1 v( e, a7 K* O' @engine; you can still run all of the color adjusting post-processing effects a' `! k ?1 v3 q4 b) w# n; B
nd accelerate a maximum of two 1080p streams at the same time.
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ATI claims that the GPU now supports Blu-ray playback/acceleration in Aero mod
# L- }, b3 B& X0 V7 M( te, but I found that in my testing the UI still defaulted to basic mode.
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( ?& `7 Y+ A7 O; w* X, }To take advantage of the 5870's bitstreaming support I had to use a pre-releas
1 \/ A% p4 E& K# p7 t1 a: X8 Ue version of Cyberlink's PowerDVD 9. The public version of the software should% z$ l$ y0 o! ]
be out in another week or so. To enable TrueHD/DTS-HD MA bitstreaming you hav
# L! S/ J2 ~% p& F2 c1 `' fe to select the "Non-decoded high-definition audio to external device" option
- D8 u: k% R w7 ^in the audio settings panel:
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With that selected the player won't attempt to decode any audio but rather pas
: v$ n/ ]/ w; e( q- Z, }/ R9 |. qs the encoded stream over HDMI to your receiver. In this case I had an Integra' ?- Z7 p$ E" p2 l1 c% F
DTC-9.8 on the other end of the cable and my first test was Bolt, a DTS-HD MA' ~7 S, q+ [/ ~. s( ?8 p" f
title. Much to my amazement, it worked on the first try:
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! I* F: M8 K0 W' }2 ~& WNo HDPC errors, no strange player issues, nothing - it just worked. % ]( k3 x& h$ @7 ]6 P, K
C4 T5 {/ i; p }Next up was Dolby TrueHD. I tried American History X first but the best I coul
$ o) C' {) s' Q% Ud 【请注意文明用词】 of it was Dolby Digital. I swapped in Transformers and found the sam
' b* [! g6 g( q5 G' u# C' N9 He. This ended up being an issue with the early PowerDVD 9 build, similar to is
5 J9 \. ?1 Z) u, {& C! {sues with the version of the player needed for the Auzentech HomeTheater HD. S: T4 T* G: r. A' k
witching audio output modes a couple of times seemed to fix the problem, I now
& c8 w/ _/ N9 p# Q- s) n% V- l8 t9 qhad both DTS-HD MA and Dolby TrueHD bitstreaming from the Radeon HD 5870 to m4 H+ H& o4 G/ p9 u4 N' Q# H
y receiver.
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One strange artifact during my testing was the 5870 apparently delivered 1080i
. K6 q$ V, {# Q( Q* Foutput to my JVC RS2 projector. I'm not exactly sure what went wrong here as
; M8 k; k. h9 N3 _# J* R1080p wasn't an issue on any other display I used. I ran out of time before I
% [# ~2 \3 g. ?4 w: G, G7 h3 V8 Icould figure out the cause of the problem but I expect it's an early compatibi' K4 ^3 c, y6 @$ {( a. F. ^$ B" w
lity issue. ) M- a2 Q0 ]+ z; w' e* x9 e# h
' _0 Q! E' Z0 |! aI can't begin to express how relieving it is to finally have GPUs that impleme6 D4 @2 {7 I% E7 @1 F
nt a protected audio path capable of handling these overly encrypted audio str
9 x1 V+ e/ t3 { T$ ]; S% _eams. Within a year everything from high end GPUs to chipsets with integrated " e/ C6 I' L5 P X; S) z
graphics will have this functionality. |
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发表于 2009-9-22 14:33
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