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http://we.pcinlife.com/redirect.php?tid=1259597&goto=lastpost: t9 K6 x W& u, F
http://www.anandtech.com/video/showdoc.aspx?i=3643&p=10 6 l1 F2 V' o" [3 G
. W- O- w2 B* r. w: b! M! yThe Race is Over: 8-channel LPCM, TrueHD & DTS-HD MA Bitstreaming! t6 N# H5 Q; G1 |& |5 |& b
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It's now been over a year since I first explained the horrible state of Blu-ra
# P* {! W2 M$ |, e1 o' I2 Q! G5 [' zy audio on the PC. I'm not talking about music discs, but rather the audio com! ?9 I5 P' j- m6 ~- c' M" N
ponent of any Blu-ray movie. It boils down to this: without an expensive sound& C& O' {! j" f. u. _6 R
card it's impossible to send compressed Dolby TrueHD or DTS-HD Master Audio s) G7 p j* H7 @
treams from your HTPC to an AV receiver or pre-processor. Thankfully AMD, Inte: L, d. N9 s: V! i$ m$ c
l and later NVIDIA gave us a stopgap solution that allowed HTPCs, when equippe
5 Q( u. p* S U4 a' Q b) @' [d with the right IGP/GPU, to decode those high-definition audio streams and se% {* v% Y2 P4 r3 E
nd them uncompressed over HDMI. The feature is commonly known as 8-channel LPC/ W- s3 q) N- _; \0 |
M support and without it all high end HTPC users would be forced into spending
+ x+ P4 p9 O0 |# ?7 Ganother $150 - $250 on a sound card like the Auzentech HomeTheater HD I just
( ?8 r$ y. }/ d/ [; Drecently reviewed.
: W+ T* N) A* v `, b- n" D
/ B" g% I0 S2 U! `6 H/ DFor a while I'd heard that ATI was dropping 8-channel LPCM support from RV870 ) C+ t% B1 N8 u; w' P. s0 F
because of cost issues. Thankfully, those rumors turned out to be completely u5 k( M$ |4 N, |, i; n) J) s4 |' L6 U
ntrue. Not only does the Radeon HD 5870 support 8-channel LPCM output over HDM8 i* a$ x8 n T2 H( k/ r/ E
I like its predecessor, but it can now also bitstream Dolby TrueHD and DTS-HD
+ Q1 B0 N# W5 K" J) O1 G$ hMA. It is the first and only video card to be able to do this, but I expect ot
. {( n" E. y( K8 @7 w" b) V& shers to follow over the next year.
/ o5 I9 O: D* ~. s) ?+ Z; m+ S& M }9 ^
The Radeon HD 5870 is first and foremost a card for gamers, so unless you're b3 R0 d8 `; q. J6 p4 O8 ^
uilding a dual-purpose HTPC, this isn't the one you're going to want to use. I
- e6 J6 a7 C+ b" lf you can wait, the smaller derivatives of the RV870 core will also have bitst2 i# o. H3 L5 F, V; P5 v
reaming support for TrueHD/DTS-HD MA. If you can't and have a deep enough HTPC3 R* a; A4 i5 k, Q/ X& @8 `8 b
case, the 5870 will work. / @% P0 c* F ^; v0 n: N
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In addition to full bitstreaming support, the 5870 also features ATI's UVD2 (U0 ^7 M7 W; k- D0 P
niversal Video Decoder). The engine allows for complete hardware offload of al
: R7 A# v6 R# i+ x) o: hl H.264, MPEG-2 and VC1 decoding. There haven't been many changes to the UVD2 ' W. r' V: w: P3 Y2 l
engine; you can still run all of the color adjusting post-processing effects a2 ~ k2 G, W$ Q% k8 w
nd accelerate a maximum of two 1080p streams at the same time.9 |/ S0 u9 k7 a8 j2 k' B& u
. m$ m x8 A3 | z! t* f" i' T
ATI claims that the GPU now supports Blu-ray playback/acceleration in Aero mod
; |* T- c& C# i: H9 L5 Me, but I found that in my testing the UI still defaulted to basic mode.' Y! U9 y4 u2 \" z
* o- W) j2 J" p! C( @" Y, b. M- g
To take advantage of the 5870's bitstreaming support I had to use a pre-releas
+ K5 T4 W' ^0 ]3 n. Be version of Cyberlink's PowerDVD 9. The public version of the software should: E$ K4 E+ b$ ~; _ S5 D" W$ G8 N
be out in another week or so. To enable TrueHD/DTS-HD MA bitstreaming you hav1 }0 ]& C8 U- O/ K
e to select the "Non-decoded high-definition audio to external device" option
" c8 e- i# F" F2 ]in the audio settings panel:
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With that selected the player won't attempt to decode any audio but rather pas6 G* |0 j4 f% ~) r' q# x; \' F
s the encoded stream over HDMI to your receiver. In this case I had an Integra
% E/ e0 s: `+ B5 Z: X- p# gDTC-9.8 on the other end of the cable and my first test was Bolt, a DTS-HD MA- V4 j" K! u3 _8 s7 G
title. Much to my amazement, it worked on the first try:; r9 }/ l" K4 D( z
( q) U, z3 t0 a3 `% E0 MNo HDPC errors, no strange player issues, nothing - it just worked. ) ]& N3 A0 ]2 L0 S, n- |5 [. K
" H/ m3 e7 s/ DNext up was Dolby TrueHD. I tried American History X first but the best I coul9 c3 h2 f3 c6 N
d 【请注意文明用词】 of it was Dolby Digital. I swapped in Transformers and found the sam
8 ~7 _$ _' P# Me. This ended up being an issue with the early PowerDVD 9 build, similar to is& q& O c$ s) a/ X v
sues with the version of the player needed for the Auzentech HomeTheater HD. S
: [4 X* M ~2 X6 U& Z+ h* Zwitching audio output modes a couple of times seemed to fix the problem, I now
5 j. g# p" }7 s" u1 H! fhad both DTS-HD MA and Dolby TrueHD bitstreaming from the Radeon HD 5870 to m1 _/ I+ R; z# |/ |
y receiver.
$ R) I7 f8 q0 p! ~/ R: b5 j$ l/ q* h' X/ \3 y* s
One strange artifact during my testing was the 5870 apparently delivered 1080i" K. F3 I% O$ B! ]) k
output to my JVC RS2 projector. I'm not exactly sure what went wrong here as 8 G( | m6 r4 o; |" T
1080p wasn't an issue on any other display I used. I ran out of time before I
: }4 ], L4 C* \- ocould figure out the cause of the problem but I expect it's an early compatibi
+ N' n/ S$ T3 |* F i# flity issue. " N/ |& {. p' D* V$ H
1 i2 h* s. {& |& ^
I can't begin to express how relieving it is to finally have GPUs that impleme
. V8 F4 w" i: w# {! bnt a protected audio path capable of handling these overly encrypted audio str
. o* n& T$ u: O5 s+ ]eams. Within a year everything from high end GPUs to chipsets with integrated
7 J$ ] P5 ?( d) ~% }: P: K" ]graphics will have this functionality. |
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发表于 2009-9-22 14:33
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