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http://we.pcinlife.com/redirect.php?tid=1259597&goto=lastpost
& w$ t4 w+ [3 M! W. G% V7 `7 ~http://www.anandtech.com/video/showdoc.aspx?i=3643&p=10
[7 x/ R9 z0 M9 j* f p% x- I, E' J. U$ q: U+ O z3 M
The Race is Over: 8-channel LPCM, TrueHD & DTS-HD MA Bitstreaming
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1 F3 K* ]- s8 Y) |8 ^8 O' XIt's now been over a year since I first explained the horrible state of Blu-ra
T! [1 D9 D4 n% ?) v5 X& K g5 Uy audio on the PC. I'm not talking about music discs, but rather the audio com
4 q3 v8 z1 k1 _4 \! \ g* ~$ u' mponent of any Blu-ray movie. It boils down to this: without an expensive sound
, h$ N q4 I; e# W5 r7 G1 Rcard it's impossible to send compressed Dolby TrueHD or DTS-HD Master Audio s( H# }- o. k" o6 l3 N3 q' p0 w! T* s
treams from your HTPC to an AV receiver or pre-processor. Thankfully AMD, Inte
O7 X7 i( Q5 F5 q+ fl and later NVIDIA gave us a stopgap solution that allowed HTPCs, when equippe
% D! c; h; H; `1 Wd with the right IGP/GPU, to decode those high-definition audio streams and se
. Y0 j# \) o! rnd them uncompressed over HDMI. The feature is commonly known as 8-channel LPC0 b9 n6 O+ \, F) @! w( Z
M support and without it all high end HTPC users would be forced into spending
5 m; }% r9 n) Kanother $150 - $250 on a sound card like the Auzentech HomeTheater HD I just
% C. G* e( X/ G$ c' urecently reviewed. 7 q; a0 b! U' R3 \! I( N
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For a while I'd heard that ATI was dropping 8-channel LPCM support from RV870 0 h3 i7 K, D" H, t C' G7 A
because of cost issues. Thankfully, those rumors turned out to be completely u
' l3 X7 l% y8 E2 ~. Lntrue. Not only does the Radeon HD 5870 support 8-channel LPCM output over HDM
% `. N# K9 U0 i; F* a1 ^: yI like its predecessor, but it can now also bitstream Dolby TrueHD and DTS-HD + c4 E& {3 o- d/ `3 K; X' U6 W
MA. It is the first and only video card to be able to do this, but I expect ot6 |9 t( Y) q3 K1 r
hers to follow over the next year.
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# L6 L: r1 E* _, O9 pThe Radeon HD 5870 is first and foremost a card for gamers, so unless you're b
q* u( s X1 F; s3 _5 g5 j6 iuilding a dual-purpose HTPC, this isn't the one you're going to want to use. I. E+ o+ a+ L' R! G
f you can wait, the smaller derivatives of the RV870 core will also have bitst
3 I7 Z6 {) ?& v" Mreaming support for TrueHD/DTS-HD MA. If you can't and have a deep enough HTPC
! a7 E& ?2 s4 I$ w$ b: Ccase, the 5870 will work.
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In addition to full bitstreaming support, the 5870 also features ATI's UVD2 (U
1 r& R; _0 T1 v+ N, z* W/ g: [niversal Video Decoder). The engine allows for complete hardware offload of al
9 B& l5 `* d" y# v8 B* I9 N5 nl H.264, MPEG-2 and VC1 decoding. There haven't been many changes to the UVD2
/ ?; a% X- a2 v; q; L6 _1 @engine; you can still run all of the color adjusting post-processing effects a3 ^: q: b3 [1 ^
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% c" z0 T* n. I
e, but I found that in my testing the UI still defaulted to basic mode., G2 D/ o- i7 W( Z e: |' B
" v* d. _! O2 T) W
To take advantage of the 5870's bitstreaming support I had to use a pre-releas
# `( w0 V) F( {' ^7 Oe version of Cyberlink's PowerDVD 9. The public version of the software should/ [- A- R8 a# A7 ^" |, G
be out in another week or so. To enable TrueHD/DTS-HD MA bitstreaming you hav4 d" P6 ^( w* D- ]! p1 a7 o
e to select the "Non-decoded high-definition audio to external device" option 2 A) }9 }' \. j$ _/ h
in the audio settings panel:# Z) F7 A2 {; ]" I1 O$ {* Y( f
' z# m4 k+ K+ E2 X( g3 `& DWith that selected the player won't attempt to decode any audio but rather pas3 o& B6 M s _: V
s the encoded stream over HDMI to your receiver. In this case I had an Integra2 r3 n+ m1 ?% B: _
DTC-9.8 on the other end of the cable and my first test was Bolt, a DTS-HD MA( M" P0 `" L/ w' m+ u
title. Much to my amazement, it worked on the first try:+ O& R% h8 c& Z
, Z2 F9 _* R( DNo 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
8 R6 r1 A6 D; q2 \d 【请注意文明用词】 of it was Dolby Digital. I swapped in Transformers and found the sam, X* c/ T5 A9 k" P. H4 C
e. This ended up being an issue with the early PowerDVD 9 build, similar to is
4 ?8 d" t9 L, [& S7 p6 Jsues with the version of the player needed for the Auzentech HomeTheater HD. S, C: {. J. \# Z; [$ h
witching audio output modes a couple of times seemed to fix the problem, I now0 E! P$ D( ~9 z/ p% | D$ ~5 p4 N
had both DTS-HD MA and Dolby TrueHD bitstreaming from the Radeon HD 5870 to m
- {& {- g. |: k% Q% qy receiver." l: E2 A! X$ j0 X/ X
0 m' ?1 z, |* X- l( xOne strange artifact during my testing was the 5870 apparently delivered 1080i
' o: d3 o' r7 E+ j6 B2 q, N6 ?" }* A. uoutput to my JVC RS2 projector. I'm not exactly sure what went wrong here as
# p4 N9 D' T2 d. i: ~1080p wasn't an issue on any other display I used. I ran out of time before I
& S0 m( z8 I( H5 ~" Y1 c5 A' X1 Bcould figure out the cause of the problem but I expect it's an early compatibi+ B0 H4 D2 U$ F6 l: @/ V% k& f
lity issue. : E5 q+ G" w/ d- _" ]: l
3 X. L$ J: b' G8 Y6 [7 k) f9 ]I can't begin to express how relieving it is to finally have GPUs that impleme/ i4 U9 I! {' q6 g" a3 N v
nt a protected audio path capable of handling these overly encrypted audio str
' w/ @' o' j6 O5 c4 keams. Within a year everything from high end GPUs to chipsets with integrated
) ~; _" i) S* Kgraphics will have this functionality. |
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