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http://we.pcinlife.com/redirect.php?tid=1259597&goto=lastpost
9 A, D$ c @* v" a% khttp://www.anandtech.com/video/showdoc.aspx?i=3643&p=10 : K; \" v# i/ ~, B# [. X
! I m7 p# ^4 t0 m" O8 z+ CThe Race is Over: 8-channel LPCM, TrueHD & DTS-HD MA Bitstreaming- B; l7 Z- o# k$ j) t; m: k
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It's now been over a year since I first explained the horrible state of Blu-ra
7 @4 x' W9 E' l, w7 l xy audio on the PC. I'm not talking about music discs, but rather the audio com
4 o3 u5 G, y: h4 U7 Cponent of any Blu-ray movie. It boils down to this: without an expensive sound
% H/ e. d, z- S% dcard it's impossible to send compressed Dolby TrueHD or DTS-HD Master Audio s9 @, S3 C* _9 ~$ D( ?
treams from your HTPC to an AV receiver or pre-processor. Thankfully AMD, Inte' ^: `2 K. N' o4 {; n. }
l and later NVIDIA gave us a stopgap solution that allowed HTPCs, when equippe
8 A8 y; l, G7 u3 Hd with the right IGP/GPU, to decode those high-definition audio streams and se
. U! v6 D( w6 z( z1 and them uncompressed over HDMI. The feature is commonly known as 8-channel LPC
9 S$ C: ]1 K4 Z# }5 ~M support and without it all high end HTPC users would be forced into spending. Q% M- q; X9 E1 @& }3 e
another $150 - $250 on a sound card like the Auzentech HomeTheater HD I just
: T' L5 r9 Q+ m6 Irecently reviewed. 5 V* c0 X, [6 U& F" V. I
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For a while I'd heard that ATI was dropping 8-channel LPCM support from RV870 2 x: G1 B+ B" L6 W0 i
because of cost issues. Thankfully, those rumors turned out to be completely u, {2 n C6 V8 P1 O1 o9 }
ntrue. Not only does the Radeon HD 5870 support 8-channel LPCM output over HDM
8 [/ u* P$ t7 S x) I( l( t) ]+ MI like its predecessor, but it can now also bitstream Dolby TrueHD and DTS-HD
- k% v7 l; Y" w2 O3 V$ z9 wMA. It is the first and only video card to be able to do this, but I expect ot+ B; j& X+ F9 i# k0 n: ]
hers to follow over the next year. ; n# S' L: b+ o* I1 Y
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The Radeon HD 5870 is first and foremost a card for gamers, so unless you're b
5 \( A, H( o4 v! Guilding a dual-purpose HTPC, this isn't the one you're going to want to use. I4 [8 M8 n7 H7 n4 a6 f: {7 t( }
f you can wait, the smaller derivatives of the RV870 core will also have bitst
0 F9 ^4 R/ s% g; ]: [) ereaming support for TrueHD/DTS-HD MA. If you can't and have a deep enough HTPC
7 R. k- ] H5 s. L' T9 [) Fcase, the 5870 will work.
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In addition to full bitstreaming support, the 5870 also features ATI's UVD2 (U6 @2 Z7 X$ x, Y h" Z$ H) K
niversal Video Decoder). The engine allows for complete hardware offload of al+ n" u0 S0 a; C/ J4 _+ X! i
l H.264, MPEG-2 and VC1 decoding. There haven't been many changes to the UVD2
/ h1 ~* m2 e* u! nengine; you can still run all of the color adjusting post-processing effects a) h) A$ Q; _! Y) H1 F: {
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
* M+ H- S+ Z) Z, [# ^ h+ Re, but I found that in my testing the UI still defaulted to basic mode.
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To take advantage of the 5870's bitstreaming support I had to use a pre-releas; T& U$ o8 S: R: f' M4 D8 z3 a; i! b
e version of Cyberlink's PowerDVD 9. The public version of the software should
7 O$ n& Q$ Z! h: D7 k9 vbe out in another week or so. To enable TrueHD/DTS-HD MA bitstreaming you hav
4 J8 b4 K1 A% G0 X& s0 L3 ^e to select the "Non-decoded high-definition audio to external device" option
. D5 R) ?6 h7 n+ ?0 Nin the audio settings panel:. _" Y- e! y# y% O( D4 Z. V3 ^
- F- K) c, |: y" G, M0 BWith that selected the player won't attempt to decode any audio but rather pas
1 ~- N% y. d! n# T! ys the encoded stream over HDMI to your receiver. In this case I had an Integra
' _, {0 B8 u; M" p" ^- k6 SDTC-9.8 on the other end of the cable and my first test was Bolt, a DTS-HD MA
/ t0 c2 S9 o1 I' z. ^0 K6 Ntitle. Much to my amazement, it worked on the first try:
+ [$ k' }8 d: D$ ]
0 b& w% O0 h5 U3 S( |! c1 zNo HDPC errors, no strange player issues, nothing - it just worked.
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Next up was Dolby TrueHD. I tried American History X first but the best I coul
6 @1 v' N$ A0 z$ md 【请注意文明用词】 of it was Dolby Digital. I swapped in Transformers and found the sam+ {" w+ s. p' {* _- z1 O R- B
e. This ended up being an issue with the early PowerDVD 9 build, similar to is5 c) t1 k C+ }1 b4 p
sues with the version of the player needed for the Auzentech HomeTheater HD. S
6 s0 q. s0 ^: n6 d4 P+ Pwitching audio output modes a couple of times seemed to fix the problem, I now$ Q% Q5 B% H) u
had both DTS-HD MA and Dolby TrueHD bitstreaming from the Radeon HD 5870 to m" m# l% C# S/ V8 f* z# t
y receiver.
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One strange artifact during my testing was the 5870 apparently delivered 1080i) y2 ^, i' b1 X* n- Q8 E% K
output to my JVC RS2 projector. I'm not exactly sure what went wrong here as
4 v3 k) `9 e1 {+ H, A8 L- T1080p wasn't an issue on any other display I used. I ran out of time before I
5 Y- }! M' p% ]1 {8 W! f$ ccould figure out the cause of the problem but I expect it's an early compatibi* A% K8 l0 ^. f% R
lity issue. $ y U. J& `: Y6 E! D& t% N
) [0 `9 P" h4 J5 _5 G5 xI can't begin to express how relieving it is to finally have GPUs that impleme
1 l& q8 t( E) d( m' ?3 M0 fnt a protected audio path capable of handling these overly encrypted audio str
8 X$ {3 s: e5 W/ N7 v: eeams. Within a year everything from high end GPUs to chipsets with integrated
* j4 r% B/ C; s4 I4 {( I* \$ cgraphics will have this functionality. |
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