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http://we.pcinlife.com/redirect.php?tid=1259597&goto=lastpost
8 J3 d* W8 J- n/ [; L/ T9 |http://www.anandtech.com/video/showdoc.aspx?i=3643&p=10
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2 e* U( B' e. B0 s1 l% Y# BThe Race is Over: 8-channel LPCM, TrueHD & DTS-HD MA Bitstreaming' p# {; E# }# _7 R! c2 K S
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It's now been over a year since I first explained the horrible state of Blu-ra
4 M& B3 e$ n9 ?/ gy audio on the PC. I'm not talking about music discs, but rather the audio com
% H( b) c) x1 s3 W8 G4 o! Gponent of any Blu-ray movie. It boils down to this: without an expensive sound$ A3 V% W, f" R% |
card it's impossible to send compressed Dolby TrueHD or DTS-HD Master Audio s3 W" @4 c; v7 g! b7 [4 U5 z
treams from your HTPC to an AV receiver or pre-processor. Thankfully AMD, Inte) x. G) [6 T. I+ o. W8 y4 R2 W
l and later NVIDIA gave us a stopgap solution that allowed HTPCs, when equippe
+ u6 b: y3 ^& N& |d with the right IGP/GPU, to decode those high-definition audio streams and se2 f2 }5 j8 K% q- U% }7 {
nd them uncompressed over HDMI. The feature is commonly known as 8-channel LPC# n. D5 [: Q& |$ `5 L5 }
M support and without it all high end HTPC users would be forced into spending
$ y3 l0 V4 ^; ?7 R7 p0 ganother $150 - $250 on a sound card like the Auzentech HomeTheater HD I just
4 T# L5 h3 ?# v. z# A& ]5 _1 Mrecently reviewed.
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2 K. D8 V5 n, H6 LFor a while I'd heard that ATI was dropping 8-channel LPCM support from RV870 l9 L s$ d. L3 d6 Q) E: `0 t
because of cost issues. Thankfully, those rumors turned out to be completely u3 o5 N- J$ `1 w. _8 i* q* _. p& _( ?
ntrue. Not only does the Radeon HD 5870 support 8-channel LPCM output over HDM. {3 l4 q" J$ F: i
I like its predecessor, but it can now also bitstream Dolby TrueHD and DTS-HD ' C+ ]- Y) N0 X) e. Z' Z
MA. It is the first and only video card to be able to do this, but I expect ot% J( v% A" r6 f, x9 s
hers to follow over the next year.
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( b+ x3 K5 g; [( J' GThe Radeon HD 5870 is first and foremost a card for gamers, so unless you're b# q) G* B/ ?, o* N
uilding a dual-purpose HTPC, this isn't the one you're going to want to use. I0 {" T7 }6 k: j' z: L, n
f you can wait, the smaller derivatives of the RV870 core will also have bitst7 g4 P% q3 ]" R [ u
reaming support for TrueHD/DTS-HD MA. If you can't and have a deep enough HTPC
. A/ P% N3 x4 `- T1 g$ ecase, the 5870 will work. ) l5 y& t; R; l. @0 n
) ]/ e3 o5 X5 X* k8 EIn addition to full bitstreaming support, the 5870 also features ATI's UVD2 (U
4 l) ?/ P. ~2 [; L" nniversal Video Decoder). The engine allows for complete hardware offload of al
) ^! ]" {, z$ C# F1 S4 ~) Hl H.264, MPEG-2 and VC1 decoding. There haven't been many changes to the UVD2 " F5 w6 Z3 q0 v8 D6 h: c; [- I( r
engine; you can still run all of the color adjusting post-processing effects a
) A8 R8 }" o9 O; }/ p4 {* m" Dnd accelerate a maximum of two 1080p streams at the same time.
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2 h: ~( M% j4 ^6 r8 dATI claims that the GPU now supports Blu-ray playback/acceleration in Aero mod
0 m g" S$ C8 d+ K/ A `e, but I found that in my testing the UI still defaulted to basic mode.: U u6 \% f( d; F
% @6 ^. v, } A, rTo take advantage of the 5870's bitstreaming support I had to use a pre-releas7 T; y6 \1 q3 @
e version of Cyberlink's PowerDVD 9. The public version of the software should
( b3 J, t, F2 U- N. Tbe out in another week or so. To enable TrueHD/DTS-HD MA bitstreaming you hav% b! W% {) V2 w
e to select the "Non-decoded high-definition audio to external device" option 9 B0 b0 a% [" j# f
in the audio settings panel:! h* E# \8 l/ F3 V
1 R. T" g6 V7 n" Q' l7 u7 Z! z4 v. OWith that selected the player won't attempt to decode any audio but rather pas
+ q( K# }' s9 o( J8 js the encoded stream over HDMI to your receiver. In this case I had an Integra" p: h" [" A) ^% W
DTC-9.8 on the other end of the cable and my first test was Bolt, a DTS-HD MA
! u/ R1 d; b9 I$ w- Ptitle. 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. 3 ^# W/ b, J! G* i4 d6 ]
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Next up was Dolby TrueHD. I tried American History X first but the best I coul
1 F% ^% d2 s# q) H8 @d 【请注意文明用词】 of it was Dolby Digital. I swapped in Transformers and found the sam9 d3 m- m# G: v, T
e. This ended up being an issue with the early PowerDVD 9 build, similar to is
@% T6 u# r& Esues with the version of the player needed for the Auzentech HomeTheater HD. S/ }" G; ?1 Q+ o$ x2 v
witching audio output modes a couple of times seemed to fix the problem, I now4 p. n5 p3 ? g
had both DTS-HD MA and Dolby TrueHD bitstreaming from the Radeon HD 5870 to m$ @" G ]" L+ I$ N
y receiver.
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One strange artifact during my testing was the 5870 apparently delivered 1080i
* _7 E* [$ a* m7 C' Moutput to my JVC RS2 projector. I'm not exactly sure what went wrong here as
# J4 F. W; K6 B3 I3 x' Q s1080p wasn't an issue on any other display I used. I ran out of time before I 0 A1 H; o @2 n1 T1 K
could figure out the cause of the problem but I expect it's an early compatibi) t( \$ Q. l _# `6 f
lity issue.
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I can't begin to express how relieving it is to finally have GPUs that impleme2 Q! P& A" }9 r
nt a protected audio path capable of handling these overly encrypted audio str
2 y( @4 O% {7 a7 l3 j' B( q/ meams. Within a year everything from high end GPUs to chipsets with integrated
9 n" d% K6 M* X2 |! ygraphics will have this functionality. |
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发表于 2009-9-22 14:33
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