Xbox audio bitrate=640 kbps DD 5.1

SteveRS

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Apr 8, 1999
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Not 384 or 448 kbps, but 640kbps DD5.1 according to my Sony TA-E9000ES processor. Very cool!
Now back to the games!
 

Scott L

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Cool, thanks for the info Steve. Is it just me or can anyone else hear the compression in the voices in Halo? In big action scenes it might be harder to notice but you can tell in the opening cinema.
 

Camp

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Steve, what game got that reading? Is it consistant throughout the game?
 

Max Leung

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640kbps? No way! Does that mean some processors will have trouble with the DD5.1? My Yammie DSP-A1 has no problem with it.
In Halo, I do notice that the voices are a bit compressed sounding, although it could also be that the center channel seems to be lower than the rest of the speakers!
 

Sean Oneil

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If the voices sound overly compressed, it is most likely not the fault of the DD codec ...rather, it is probably due to the original sample waves.
While the DD decoder chip in the X-Box may output at 640kbps or what have you, this does not mean that the original wave files were not much more heavily compressed.
I am guessing that the system uncompresses the packed wave files and then looks to the DD decoder to re-process, and steer the SFX around the soundstage. Just a guess though.
In any case, the compressed voice sound should not be the fault of the DD codec, as most of us have heard DD tracks on DVD at 448kbps or lower with no such problems.
[Edited last by Sean Oneil on November 15, 2001 at 06:33 PM]
 

Dean Cooper

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The voices in Halo are that way for a reason, its a style detail because your head is in a helmet and the voices are over a radio. Scary isn't it

Dean
 

SteveRS

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I have tried Halo and Munche.
The opening choir music at the menu screen of Halo is impressive in DD5.1 with a nice large hall effect.
As soon as the games load, the bitrate displays as 640kbps on the TA-E9000ES and continues thru all gameplay.
The only other dvd that I own, besides Xbox games, that displays 640kbps is Delos DVD Spectacular.
It was released within the first months of the launch of the dvd format.
There is a hidden track (ch29) of the 1812 Overture that when accessed displays this message...
"Please note: The Dolby Digital audio in this "hidden" track has been encoded at a data rate of 640 kb/s, which differs from the standard DVD specification."
"Because of this variation, player inability to access this data should not be considered a defect."
(in 1997 only the Sony S7000 could)
"Dolby Laboratories and Delos International have included this selection on this disc for testing purposes."
Maybe Dolby is testing again with the Xbox

Hopefully someone can report back with the bitrate displayed on their DD processor to confirm.
 

Max Leung

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Well, I'm not sure if this is a problem or not, but I get ZERO center channel activity in DD5.1, at least with Halo.
Can anyone confirm this? I can hear dialog no problem, but I have no center channel information...no wonder I thought the center channel output was low!
(The other channels check out no problem)
[Edited last by Max Leung on November 15, 2001 at 10:40 PM]
 

Mike_G

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I checked my center channel specifically and it was working fine.
Mike
 

Max Leung

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Did you check it with Halo specificly? Clearly, if you just boot up the xbox with no disc in the drive, it will sound like the center channel is working because your processor would go into Dolby Pro Logic.
This is starting to worry me...
So far, my center channel is completely quiet. My Yammie DSP-A1 correctly identifies the bitstream as 3/2.1 (3 front, 2 rear, 1 LFE). However, not a peep from the center speaker. Sound effects sound ok, and the center effects seem to be mixed between the two left and right mains.
Perhaps Halo is actually a 4.1 game?
I double checked my xbox audio settings...enabling Dolby Digital forces Audio Mode to be Dolby Surround (the audio mode cannot be changed to anything else without disabling DD).
I get no center channel activity anywhere in the game, including the opening Microsoft logo when you first boot the game.
[Edited last by Max Leung on November 15, 2001 at 11:45 PM]
 

Mike_G

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Max,
Yes I did. Just one spot where Cordala was speaking - I put my ear up to the center channel and her voice came right from it. It was fast - I wanted to make sure that this was a real 5.1 game since we've been hearing all these bad things about SSX Tricky's DTS issue.
Mike
 

Max Leung

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Thanks Mike! You are absolutely right...I heard Cordala's voice very clearly from the center speaker. I have a save spot just after the escape pod landed on Halo, where she asks if you are alright.
So far, it seems center channel info is reserved for Cordala's voice. My guess is that it may also be used for suit status information and whatnot. Weapons fire and environmental effects do not get directed to the center speaker.
Phew, thought something was screwy with my xbox. Now, at least, I can be assured that either many xboxes are screwed, or it's just the way the game was designed.

[Edited last by Max Leung on November 15, 2001 at 11:50 PM]
 

Mike_A

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from what i understand, all DD decoders (with the exception of a few built-in to DVD players) SHOULD handle a 640kbps DD stream just fine. I highly doubt M$ would risk a serious incompatibility like this, especially when lower data rates are commonly used on DVD's and clearly sound just fine.
 

GregK

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Nov 22, 2000
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Mike_A, you are correct. Roger Dressler from Dolby has
stated this several times before. DD decoders in DVD
players are excempted however, because the highest bitrate
they will ever see is 448kb/s, per limitations in the
DVD spec itself set by the original DVD Steering Committe.
Even so, my Sony DVD player can output the hidden track
#29 at the DD 640kb/s bitstream to my Yamaha receiver,
which of course decodes it fine. (Current DVD players are
NOT required to pass any DD bitstream higher than 448kb/s)
The Sony's internal DD decoder also can decode the 640kb/s
track internally and output a 2-channel downmix as well.
 

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