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http://we.pcinlife.com/redirect.php?tid=1259597&goto=lastpost
7 _! j+ s! f. h* u- Z9 ~1 {- ?http://www.anandtech.com/video/showdoc.aspx?i=3643&p=10
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4 U7 Z' Y/ }! F- U2 J7 M4 QThe Race is Over: 8-channel LPCM, TrueHD & DTS-HD MA Bitstreaming
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: [+ v' V( Q, A$ dIt's now been over a year since I first explained the horrible state of Blu-ra
/ E% P5 b( w, h$ gy audio on the PC. I'm not talking about music discs, but rather the audio com
/ q0 _- k# ]# d* Zponent of any Blu-ray movie. It boils down to this: without an expensive sound1 q$ S% m. J( e0 ]* V
card it's impossible to send compressed Dolby TrueHD or DTS-HD Master Audio s' u, n! e( i0 [, T v$ u1 M6 E
treams from your HTPC to an AV receiver or pre-processor. Thankfully AMD, Inte2 d/ f, \6 Z* U6 B3 L. n
l and later NVIDIA gave us a stopgap solution that allowed HTPCs, when equippe
6 x+ M" _1 y' b. j; ]d with the right IGP/GPU, to decode those high-definition audio streams and se
! z3 |4 x7 v8 b! znd them uncompressed over HDMI. The feature is commonly known as 8-channel LPC
3 ?9 v. E& L( p2 l; h' cM support and without it all high end HTPC users would be forced into spending' q G7 X1 n8 t0 C# s! R% b8 R0 v
another $150 - $250 on a sound card like the Auzentech HomeTheater HD I just
2 s* y8 x" R* b( r7 `& m$ qrecently reviewed. - W; T1 T. t/ a9 h
# p' e$ N% k5 P2 D: oFor a while I'd heard that ATI was dropping 8-channel LPCM support from RV870
+ o; E2 q) e0 J4 F5 M! @ ?because of cost issues. Thankfully, those rumors turned out to be completely u
" E3 ^ @; D0 T B! _$ m; `' qntrue. Not only does the Radeon HD 5870 support 8-channel LPCM output over HDM
3 \; ]& t3 s5 M( o' U3 E7 BI like its predecessor, but it can now also bitstream Dolby TrueHD and DTS-HD % Y' w6 _& o. y1 j' i7 P
MA. It is the first and only video card to be able to do this, but I expect ot" _# o0 a" g9 b* `6 n- N
hers to follow over the next year.
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The Radeon HD 5870 is first and foremost a card for gamers, so unless you're b
/ w; a1 [8 _) `7 q7 R, e% `uilding a dual-purpose HTPC, this isn't the one you're going to want to use. I& U, d& P7 }+ o
f you can wait, the smaller derivatives of the RV870 core will also have bitst
# r6 {) k; x# _" p' n, \reaming support for TrueHD/DTS-HD MA. If you can't and have a deep enough HTPC
' R2 A, J4 L3 i. }( \case, the 5870 will work. 4 C2 g+ A8 r' z; E2 o
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In addition to full bitstreaming support, the 5870 also features ATI's UVD2 (U
# \, u1 t+ X- X* \niversal Video Decoder). The engine allows for complete hardware offload of al
n4 Y M: Y- G! ul H.264, MPEG-2 and VC1 decoding. There haven't been many changes to the UVD2
! u$ W$ [. f9 u3 f8 x* Tengine; you can still run all of the color adjusting post-processing effects a
- b, [, ~, v$ ynd accelerate a maximum of two 1080p streams at the same time.6 y, g) ~/ S' K
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ATI claims that the GPU now supports Blu-ray playback/acceleration in Aero mod% ~1 t$ b( K* i) _& f+ P
e, but I found that in my testing the UI still defaulted to basic mode.
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4 G3 R' U+ y( ^" cTo take advantage of the 5870's bitstreaming support I had to use a pre-releas) _4 T9 m1 K1 |" E) q; k
e version of Cyberlink's PowerDVD 9. The public version of the software should1 Z q( [) B3 u% c& P
be out in another week or so. To enable TrueHD/DTS-HD MA bitstreaming you hav. K: `, F4 e: M9 W" ~
e to select the "Non-decoded high-definition audio to external device" option
9 y, w6 P8 C: v1 S4 L0 g; j5 win the audio settings panel:0 i! D2 P+ u: v) Q+ \
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With that selected the player won't attempt to decode any audio but rather pas
. }9 J5 F& R* I! f: R" o9 A! zs the encoded stream over HDMI to your receiver. In this case I had an Integra
P8 b$ O6 Y/ C$ \% BDTC-9.8 on the other end of the cable and my first test was Bolt, a DTS-HD MA
: S$ |2 G1 ]4 s; q& B7 r$ jtitle. Much to my amazement, it worked on the first try:0 X9 ?# B; T+ C( n; t4 p6 p; k
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No HDPC errors, no strange player issues, nothing - it just worked.
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- R& [, d- @" i. V" K0 lNext up was Dolby TrueHD. I tried American History X first but the best I coul# Z; P' @9 M Y' f* p
d 【请注意文明用词】 of it was Dolby Digital. I swapped in Transformers and found the sam% v+ k1 l4 \- w2 I" k2 y
e. This ended up being an issue with the early PowerDVD 9 build, similar to is; `" b/ V2 U8 \0 ]* u9 V
sues with the version of the player needed for the Auzentech HomeTheater HD. S6 v1 }+ t! q0 S! v) l
witching audio output modes a couple of times seemed to fix the problem, I now' c7 \5 X# B; G) }0 n, l
had both DTS-HD MA and Dolby TrueHD bitstreaming from the Radeon HD 5870 to m
, }$ @& _( b* n! b; J) Ly receiver.
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; l7 d1 S& }; U$ T5 MOne strange artifact during my testing was the 5870 apparently delivered 1080i
( a- i* |2 w3 _( _output to my JVC RS2 projector. I'm not exactly sure what went wrong here as
, z% x& B: C3 d0 n1080p wasn't an issue on any other display I used. I ran out of time before I
+ Y9 Y4 t A& v- ^" mcould figure out the cause of the problem but I expect it's an early compatibi# @. g' q9 K- k5 V2 A
lity issue.
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' C' X5 r# d& J' Y9 A% SI can't begin to express how relieving it is to finally have GPUs that impleme7 n9 g) p5 t9 A. z
nt a protected audio path capable of handling these overly encrypted audio str
- S2 {( X6 Z7 B5 W4 @eams. Within a year everything from high end GPUs to chipsets with integrated 8 z; h! x3 O) |# h# b* x
graphics will have this functionality. |
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