Looking for: An idiots breakdown to HD-DVD audio on the X-360

Mike.P · 11-15-2006, 11:55 PM

I've done some perusing around here and I'm trying to figure out, in basic terms, how things work.

I've got the X-Box 360 HD-DVD add on, and the audio is an optical line out to our crummy 5.1 HTIB. I was reading an article about the way the code was written for the 360 drive to work, and basically here is what I'm wondering:

If I select Dolby TrueHD in the menu's, will I notice any sort of upgrade over standard DD?

I could swear, in switching the audio on the fly in Batman Begins, the TrueHD track sounded notably fuller then the standard DD, but that may just be my imagination. It was loud and awesome, either way.

Any help would be appreciated!

~Mike

Dave W · 11-16-2006, 11:15 AM

Yes, there is a differnece and you will notice it (as you mentioned). There are more technical explanations available on sites like AVS but basically, the Xbox360 converts whatever audio signal you select from the disc into DD5.1 640kbps. So on Batman Begins for example, the 360 takes the DD+ track and is uncompressing the signal and recompressing the signal. This is a lossy compression to begin with and a lossy compresison going back out but, it is still superior to standard DVD in most ways because it is encoded at a higher bitrate. When you select the True HD track it is uncompressed by the 360 just like DD+ but, True HD is not a lossy compression. So once uncompressed, you are getting the full sound field that was originally intended at its full bitrate (inside the 360) Then the 360 compresses the True HD signal to go out its optical connector so True HD is effectively only seeing "1 loss" as opposed to "2 losses" on DD+

Hope that helps...

Mike.P · 11-16-2006, 02:56 PM

Quote:

Originally Posted by Dave W

Yes, there is a differnece and you will notice it (as you mentioned). There are more technical explanations available on sites like AVS but basically, the Xbox360 converts whatever audio signal you select from the disc into DD5.1 640kbps. So on Batman Begins for example, the 360 takes the DD+ track and is uncompressing the signal and recompressing the signal. This is a lossy compression to begin with and a lossy compresison going back out but, it is still superior to standard DVD in most ways because it is encoded at a higher bitrate. When you select the True HD track it is uncompressed by the 360 just like DD+ but, True HD is not a lossy compression. So once uncompressed, you are getting the full sound field that was originally intended at its full bitrate (inside the 360) Then the 360 compresses the True HD signal to go out its optical connector so True HD is effectively only seeing "1 loss" as opposed to "2 losses" on DD+

Hope that helps...

Perfect, Dave, and thats what I figured it was doing (or something along those lines), but its helpful that someone knew for sure.

Appreciate it.

DarthBeavis · 11-16-2006, 07:20 PM

Good job Dave.



Skin Chooser:	Contact Us - Advertising Information - Home Theater Forum - Archive - Top