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http://we.pcinlife.com/redirect.php?tid=1259597&goto=lastpost
& l+ P* @# T' t$ `' k+ \http://www.anandtech.com/video/showdoc.aspx?i=3643&p=10 , }6 T' R( o1 G/ o, M {; w
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The Race is Over: 8-channel LPCM, TrueHD & DTS-HD MA Bitstreaming
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' p# |/ z P& iIt's now been over a year since I first explained the horrible state of Blu-ra
+ T6 U! u. t( d6 n5 R7 Zy audio on the PC. I'm not talking about music discs, but rather the audio com
9 {( ~4 e6 f! n% tponent of any Blu-ray movie. It boils down to this: without an expensive sound
6 H t* H) w& M- N" Gcard it's impossible to send compressed Dolby TrueHD or DTS-HD Master Audio s5 I2 u; C7 v, o$ L! g& {1 O
treams from your HTPC to an AV receiver or pre-processor. Thankfully AMD, Inte
$ P7 F2 V; m1 Q0 O6 b& ?l and later NVIDIA gave us a stopgap solution that allowed HTPCs, when equippe
8 {9 x: r7 X+ B+ Dd with the right IGP/GPU, to decode those high-definition audio streams and se
' r% E/ v+ |. ^: i& L! r( Und them uncompressed over HDMI. The feature is commonly known as 8-channel LPC
+ S- K. V6 N3 B- oM support and without it all high end HTPC users would be forced into spending
' A) F5 R$ c" i `% j$ Qanother $150 - $250 on a sound card like the Auzentech HomeTheater HD I just : a. x$ ]6 e' n- A& s% {
recently reviewed. ) b6 _' y: x7 c) h3 W
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For a while I'd heard that ATI was dropping 8-channel LPCM support from RV870 , O" Y: A6 y7 h; r" M. X" f; _8 x% Y t
because of cost issues. Thankfully, those rumors turned out to be completely u1 L ?5 e: Z+ ]( o E \, E
ntrue. Not only does the Radeon HD 5870 support 8-channel LPCM output over HDM3 ^- P3 Z @7 \9 ]3 |' k
I like its predecessor, but it can now also bitstream Dolby TrueHD and DTS-HD
$ G7 e* D- j: YMA. It is the first and only video card to be able to do this, but I expect ot
: `) q1 _9 g' q9 f4 Z! `hers to follow over the next year.
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6 O8 a* d v9 |2 R3 l8 [. RThe Radeon HD 5870 is first and foremost a card for gamers, so unless you're b
6 f* @# R4 ~) ^" muilding a dual-purpose HTPC, this isn't the one you're going to want to use. I7 {$ N' ]5 s' c* e" n5 }. @
f you can wait, the smaller derivatives of the RV870 core will also have bitst* x4 Y% W* I4 V
reaming support for TrueHD/DTS-HD MA. If you can't and have a deep enough HTPC, {& F B# j7 W5 \1 e) d' E
case, the 5870 will work. 9 t1 e3 W. f& J# M8 O$ U% D
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In addition to full bitstreaming support, the 5870 also features ATI's UVD2 (U& y. @# o6 ^4 ?6 j/ A
niversal Video Decoder). The engine allows for complete hardware offload of al
8 ?! b; Q* U/ @0 Y. k' ol H.264, MPEG-2 and VC1 decoding. There haven't been many changes to the UVD2 8 ]( J8 g2 I7 v9 E! [$ }4 \4 u
engine; you can still run all of the color adjusting post-processing effects a
$ ]6 `& M$ o* x7 c! s, w1 P% Z, xnd accelerate a maximum of two 1080p streams at the same time.- C/ H! t# h) h, @! C* p
- r. }1 Q1 h* ?% D% [ F2 r; aATI claims that the GPU now supports Blu-ray playback/acceleration in Aero mod
6 O" d+ b2 S' _) He, but I found that in my testing the UI still defaulted to basic mode.. r6 a% Y' ]& r" g5 b, l+ h! J
{# }6 d5 c2 ~$ B+ ATo take advantage of the 5870's bitstreaming support I had to use a pre-releas8 B' m% W. W; n0 H5 b% X
e version of Cyberlink's PowerDVD 9. The public version of the software should7 o f) C# q6 X5 B: n
be out in another week or so. To enable TrueHD/DTS-HD MA bitstreaming you hav
) D! D( @' {# ^( ]+ b7 he to select the "Non-decoded high-definition audio to external device" option ' [' J6 @9 x, O# k
in the audio settings panel:9 O& w, p* g) [4 A- Y' e
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With that selected the player won't attempt to decode any audio but rather pas4 b4 U9 [8 l9 o& E$ v6 T; Q+ u0 l
s the encoded stream over HDMI to your receiver. In this case I had an Integra' y, d6 c; @. ?1 q5 n$ s& j8 a1 K. m
DTC-9.8 on the other end of the cable and my first test was Bolt, a DTS-HD MA
: X' \9 u* ?8 b1 t! x/ ]title. Much to my amazement, it worked on the first try:
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6 `$ u4 T1 T9 }1 [# o. hNo HDPC errors, no strange player issues, nothing - it just worked. 3 V$ I' u- i1 M
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Next up was Dolby TrueHD. I tried American History X first but the best I coul
9 c: S! z; C$ |. T$ u4 E+ d/ o1 jd 【请注意文明用词】 of it was Dolby Digital. I swapped in Transformers and found the sam& U6 e- T: _/ q1 T/ i
e. This ended up being an issue with the early PowerDVD 9 build, similar to is
4 ] I* p2 @" Q5 s. bsues with the version of the player needed for the Auzentech HomeTheater HD. S
6 K- r, I0 S& Y% G4 d3 I# Y4 D. Bwitching audio output modes a couple of times seemed to fix the problem, I now, @; m; M7 r6 m* C, ], m; q
had both DTS-HD MA and Dolby TrueHD bitstreaming from the Radeon HD 5870 to m2 _8 J6 f+ P: v+ p
y receiver. Y7 p2 ?1 Z0 G# E j4 v; l- x
* @. U% ?) q9 mOne strange artifact during my testing was the 5870 apparently delivered 1080i
- _( `; ]- A5 ioutput to my JVC RS2 projector. I'm not exactly sure what went wrong here as
) [5 Y% X8 P, u6 H- I1080p wasn't an issue on any other display I used. I ran out of time before I
6 a; L5 s+ r* w% ]! S c8 vcould figure out the cause of the problem but I expect it's an early compatibi; s: }% Y" z# P- F$ S, l
lity issue. ! [# ?* @! j# p. o1 r, Y
/ F O- l1 [2 d% c( @2 U6 Y4 a# l$ a, hI can't begin to express how relieving it is to finally have GPUs that impleme
( f) x6 P% \! K0 V: h2 L& nnt a protected audio path capable of handling these overly encrypted audio str
. v6 M7 R( X* z+ b& l" seams. Within a year everything from high end GPUs to chipsets with integrated
! C: `6 h/ o1 s9 j4 [graphics will have this functionality. |
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发表于 2009-9-22 14:33
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