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http://we.pcinlife.com/redirect.php?tid=1259597&goto=lastpost7 W& j3 t; G1 o& w
http://www.anandtech.com/video/showdoc.aspx?i=3643&p=10 $ p) }) t& D S6 e2 q
7 m) ]7 c4 n; b* X7 M: WThe Race is Over: 8-channel LPCM, TrueHD & DTS-HD MA Bitstreaming
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! _2 R# J& P0 RIt's now been over a year since I first explained the horrible state of Blu-ra/ K( E; e6 `4 ]4 B3 D
y audio on the PC. I'm not talking about music discs, but rather the audio com( Q4 N; V6 |1 u& w1 _- _% ]
ponent of any Blu-ray movie. It boils down to this: without an expensive sound
+ R p L4 B% P+ a# [card it's impossible to send compressed Dolby TrueHD or DTS-HD Master Audio s) y# S) U$ X0 G8 S* R7 X
treams from your HTPC to an AV receiver or pre-processor. Thankfully AMD, Inte+ a; n+ C1 r9 v2 d! H3 ~3 m
l and later NVIDIA gave us a stopgap solution that allowed HTPCs, when equippe
' q, S/ {) o% B$ w1 nd with the right IGP/GPU, to decode those high-definition audio streams and se6 f& b. [& N+ ^3 K% r% V: m
nd them uncompressed over HDMI. The feature is commonly known as 8-channel LPC) u; A+ j& C& b& |% s2 l' v
M support and without it all high end HTPC users would be forced into spending
6 P. F0 r) i+ U7 d& F: T" U" danother $150 - $250 on a sound card like the Auzentech HomeTheater HD I just
( g* f/ X) j$ d a: rrecently reviewed.
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& H. P( G$ ]3 V: n/ \For a while I'd heard that ATI was dropping 8-channel LPCM support from RV870
& l1 ~' M/ p- Z Abecause of cost issues. Thankfully, those rumors turned out to be completely u* G) {5 T l+ ~ m- Q) o
ntrue. Not only does the Radeon HD 5870 support 8-channel LPCM output over HDM0 L5 ]! Y5 g) b: U8 i) k
I like its predecessor, but it can now also bitstream Dolby TrueHD and DTS-HD
8 n1 i9 k" F3 U- FMA. It is the first and only video card to be able to do this, but I expect ot( s- _. ~* }& j4 l; s
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) ^* f; h5 z( B% i
uilding a dual-purpose HTPC, this isn't the one you're going to want to use. I
+ `/ L' V. X+ vf you can wait, the smaller derivatives of the RV870 core will also have bitst1 V: T0 H7 V: V( q
reaming support for TrueHD/DTS-HD MA. If you can't and have a deep enough HTPC
. a7 k, A% ~' q! zcase, the 5870 will work.
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In addition to full bitstreaming support, the 5870 also features ATI's UVD2 (U
. K {# v$ ]! ]5 }1 qniversal Video Decoder). The engine allows for complete hardware offload of al
. l f y/ L& V y, D2 sl H.264, MPEG-2 and VC1 decoding. There haven't been many changes to the UVD2 . ?0 w0 Q; k9 ~/ M. o5 e3 G" [
engine; you can still run all of the color adjusting post-processing effects a8 |, F: @( E- j9 I, A# G/ ^
nd accelerate a maximum of two 1080p streams at the same time.. i% `! w7 V, @" w5 p5 l( K B
0 \9 \! Q0 N n2 {ATI claims that the GPU now supports Blu-ray playback/acceleration in Aero mod! `- X7 F$ z) O- y/ z% D8 U
e, but I found that in my testing the UI still defaulted to basic mode.2 `0 w3 Z; ~+ Y- x' X" [1 C
' o$ D0 g( i+ f7 V. |* b& rTo take advantage of the 5870's bitstreaming support I had to use a pre-releas
' d! B; L _0 X1 F& ie version of Cyberlink's PowerDVD 9. The public version of the software should
( i* f! @0 M$ l vbe out in another week or so. To enable TrueHD/DTS-HD MA bitstreaming you hav) z8 K8 \5 S- L) g! i3 L% b" M$ q
e to select the "Non-decoded high-definition audio to external device" option
' y2 H" G$ m" y- j) {" [+ Ain the audio settings panel:/ Q& o- U# i4 n# P5 A& |+ l9 V
1 J4 v* f" H/ r# x; E' @9 UWith that selected the player won't attempt to decode any audio but rather pas
- @! l* l+ s0 |/ O" N8 ms the encoded stream over HDMI to your receiver. In this case I had an Integra4 n- r, q, F5 O; j7 p
DTC-9.8 on the other end of the cable and my first test was Bolt, a DTS-HD MA
: `+ o5 ?$ ^7 v4 g9 L+ ~4 s9 {title. Much to my amazement, it worked on the first try:- o4 v! K1 U, Z1 R! Y" s
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No HDPC errors, no strange player issues, nothing - it just worked. % f+ E" D% c, f8 F/ j
8 R# U# I T: K+ q& f! @; y: P# }' `Next up was Dolby TrueHD. I tried American History X first but the best I coul
& T7 a8 D! V2 n1 Z, A6 Rd 【请注意文明用词】 of it was Dolby Digital. I swapped in Transformers and found the sam
6 c; e4 c& u% `$ `; ]4 d* Ge. This ended up being an issue with the early PowerDVD 9 build, similar to is
) p7 i* C6 S. r/ ^2 {sues with the version of the player needed for the Auzentech HomeTheater HD. S
5 s0 }, J7 x* _5 B/ l7 zwitching audio output modes a couple of times seemed to fix the problem, I now
0 n1 Q/ C1 a, R/ n/ G# C; B7 j& Zhad both DTS-HD MA and Dolby TrueHD bitstreaming from the Radeon HD 5870 to m w- C2 I) ~# i8 v! i, P+ }: C
y receiver.
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- D( B$ N8 u! S! l9 TOne strange artifact during my testing was the 5870 apparently delivered 1080i) B. E. g; R7 @% P' R
output to my JVC RS2 projector. I'm not exactly sure what went wrong here as + ]3 N3 h9 a4 r+ l/ H6 |
1080p wasn't an issue on any other display I used. I ran out of time before I
& h1 N& q: p+ Kcould figure out the cause of the problem but I expect it's an early compatibi4 D' `! l& B* f! ~% E! K
lity issue.
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I can't begin to express how relieving it is to finally have GPUs that impleme+ v) S0 m- L( A1 q: @
nt a protected audio path capable of handling these overly encrypted audio str
. I1 J" t& I9 u x; G, @2 ieams. Within a year everything from high end GPUs to chipsets with integrated # S3 v- P3 y) |+ J
graphics will have this functionality. |
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发表于 2009-9-22 14:33
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