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http://we.pcinlife.com/redirect.php?tid=1259597&goto=lastpost8 V4 f0 s- }# [% K* e" H
http://www.anandtech.com/video/showdoc.aspx?i=3643&p=10 . o7 q- M; K7 B9 z( E" @
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The Race is Over: 8-channel LPCM, TrueHD & DTS-HD MA Bitstreaming
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1 X+ C, K" {1 eIt's now been over a year since I first explained the horrible state of Blu-ra- L; {* H9 {1 }$ I" w+ }) S8 A! ?
y audio on the PC. I'm not talking about music discs, but rather the audio com8 e( s! j0 Q) C9 p: f! J1 x4 i. {
ponent of any Blu-ray movie. It boils down to this: without an expensive sound* ~! U e+ {- J" g+ s) u1 X
card it's impossible to send compressed Dolby TrueHD or DTS-HD Master Audio s6 p+ N7 b( X+ m& M( Q; \7 ^9 m! }
treams from your HTPC to an AV receiver or pre-processor. Thankfully AMD, Inte
$ a& o y3 M* c* m9 R" s% Wl and later NVIDIA gave us a stopgap solution that allowed HTPCs, when equippe( J+ o6 `. z: V3 j
d with the right IGP/GPU, to decode those high-definition audio streams and se
; x% ], \# R5 c q; _nd them uncompressed over HDMI. The feature is commonly known as 8-channel LPC& D2 u S( K& ? l
M support and without it all high end HTPC users would be forced into spending
" U" q* K$ J6 S& qanother $150 - $250 on a sound card like the Auzentech HomeTheater HD I just
9 k: D6 \- |9 }% f! y9 frecently reviewed.
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For a while I'd heard that ATI was dropping 8-channel LPCM support from RV870
# f7 {* [7 l7 l# R6 {0 `! I8 Cbecause of cost issues. Thankfully, those rumors turned out to be completely u
0 E) @) u) `5 N$ {* E$ l$ d* nntrue. Not only does the Radeon HD 5870 support 8-channel LPCM output over HDM) I6 t# r h( S6 g7 g
I like its predecessor, but it can now also bitstream Dolby TrueHD and DTS-HD - i: e. t, x' F: \0 f% k
MA. It is the first and only video card to be able to do this, but I expect ot
4 w& X5 h- Z3 v H+ Z2 g0 ]hers to follow over the next year.
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( f3 Q6 j2 D0 AThe Radeon HD 5870 is first and foremost a card for gamers, so unless you're b4 Z7 N+ f" [; @7 u1 a" J1 C
uilding a dual-purpose HTPC, this isn't the one you're going to want to use. I
+ @( K( R( k# j* Af you can wait, the smaller derivatives of the RV870 core will also have bitst Y# [8 Z# X& z$ ]1 }0 P& o
reaming support for TrueHD/DTS-HD MA. If you can't and have a deep enough HTPC
2 s; B5 X0 w; u# z3 F$ Dcase, the 5870 will work.
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+ t/ |# @: i6 n$ y3 b5 I2 N! }2 {In addition to full bitstreaming support, the 5870 also features ATI's UVD2 (U' ~- q1 H4 T, ~4 K% w, Y
niversal Video Decoder). The engine allows for complete hardware offload of al
" H+ }0 v# x. H M- u& Yl H.264, MPEG-2 and VC1 decoding. There haven't been many changes to the UVD2
3 q& o! R2 ]; ~+ x* J8 C; q0 i" Y& mengine; you can still run all of the color adjusting post-processing effects a( K/ |: I1 X" @
nd accelerate a maximum of two 1080p streams at the same time.
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5 \ ]' {0 b/ r& Z8 vATI claims that the GPU now supports Blu-ray playback/acceleration in Aero mod
4 o" f8 i6 E# m6 p8 E5 Ze, but I found that in my testing the UI still defaulted to basic mode.+ o$ Q" ~! t, I9 G! }; K
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To take advantage of the 5870's bitstreaming support I had to use a pre-releas
; N1 L- l5 k. z! j8 t) `9 ?e version of Cyberlink's PowerDVD 9. The public version of the software should5 R7 A, X6 o; u$ k# w8 y9 g
be out in another week or so. To enable TrueHD/DTS-HD MA bitstreaming you hav
# R/ \9 N' {0 ve to select the "Non-decoded high-definition audio to external device" option $ B1 p! z' Q; S. X# k$ @' K0 j
in the audio settings panel:
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With that selected the player won't attempt to decode any audio but rather pas' T! \/ m+ n5 v' |3 A. A) D" P
s the encoded stream over HDMI to your receiver. In this case I had an Integra
6 i m. F0 i% `$ wDTC-9.8 on the other end of the cable and my first test was Bolt, a DTS-HD MA) Q2 }# P# K( F! h* O- q! }% J: y
title. Much to my amazement, it worked on the first try:
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No HDPC errors, no strange player issues, nothing - it just worked.
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# {: m/ q* ?* E: }8 S* H; yNext up was Dolby TrueHD. I tried American History X first but the best I coul0 o" H0 m( S5 M2 I* N
d 【请注意文明用词】 of it was Dolby Digital. I swapped in Transformers and found the sam2 s. F" K! \; ~7 N
e. This ended up being an issue with the early PowerDVD 9 build, similar to is+ I8 x8 V. a( B
sues with the version of the player needed for the Auzentech HomeTheater HD. S
$ Q4 y* ~8 ^" e! @6 vwitching audio output modes a couple of times seemed to fix the problem, I now# M1 U0 y# ]8 M3 I
had both DTS-HD MA and Dolby TrueHD bitstreaming from the Radeon HD 5870 to m" c5 c4 P& g; y! `2 D/ h6 N! {
y receiver.
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7 i4 q9 X9 l) A4 n$ A& COne strange artifact during my testing was the 5870 apparently delivered 1080i
4 W; q. G4 q8 b1 Aoutput to my JVC RS2 projector. I'm not exactly sure what went wrong here as
7 p& _! e) \, g& ~3 |( C' T1080p wasn't an issue on any other display I used. I ran out of time before I
3 N' Z6 q" V7 o1 r% ocould figure out the cause of the problem but I expect it's an early compatibi
9 Y) p9 V$ Z$ a* ~: z" G8 u% Zlity issue.
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6 c! |- n' o& A; @$ ~( |2 fI can't begin to express how relieving it is to finally have GPUs that impleme
7 I3 ~/ ]/ \% k2 fnt a protected audio path capable of handling these overly encrypted audio str' r8 k/ }2 |! n) w& g' p
eams. Within a year everything from high end GPUs to chipsets with integrated 7 a: _3 a& M9 C1 P+ e
graphics will have this functionality. |
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发表于 2009-9-22 14:33
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