DD+ (HD-DVD) versus DD 5.1 (Blu-Ray)

[DanFan]

Is there a difference in audio quality between Dolby Digital+ on an HD-DVD versus Dolby Digital on the Blu-Ray?

I can think of a few examples where the HD-DVD will have DD+, but the Blu-Ray version will have only Dolby Digital 5.1.

They are:

The Cowboys
The Fugitive
Goodfellas
Terminator 3

[steve_dave]

With the titles you listed...no.

Warner encoded their Dolby Digital Plus and Dolby Digital tracks at the same 640kbs bit rate for HD DVD and DVD.

Universal for the most part used 1.5mbs Dolby Digital Plus for their HD DVDs. There are some exceptions where they used half that. This doesn't matter now since they use DTS HD Master Audio which has a 1.5mbs DTS core.

Paramount always used Dolby Digital Plus 1.5mbs on HD DVD but nearly all of thier Blu-rays have Dolby TrueHD with a Dolby Digital 640kbs secondary track. The audible difference between the two is neglible for most titles.

[JimboTHX1138]

Even though there is a few advantages to DD+ like it can have a higher bitrate than 640kbps and supports 7.1 channels, most titles used 640kbps and sounds exactly the same as DD at 640kbps.

The main reason for HD-DVD using DD+ was that DD was limited to a bitrate of 448kbps on HD-DVD just like it was on DVD. BD doesn't have that resriction. On BD Dolby labs was able to use DD at the full bitrate of 640kbps for the very first time.

[Blu Titan]

Originally Posted by JimboTHX1138

Even though there is a few advantages to DD+ like it can have a higher bitrate than 640kbps and supports 7.1 channels, most titles used 640kbps and sounds exactly the same as DD at 640kbps.

The main reason for HD-DVD using DD+ was that DD was limited to a bitrate of 448kbps on HD-DVD just like it was on DVD. BD doesn't have that resriction. On BD Dolby labs was able to use DD at the full bitrate of 640kbps for the very first time.

True enough DD+ was band aid trying to hide one of HD DVD's major flaws.

[davcole]

I have to admit, I don't find a qualitative difference between DD@640 and DD+ at 1.5. I've got several HD DVD's that are at 1.5 but they don't sound any better than the 640 tracks i've heard on BD.

In fact, i'm suprised just how good DD640 can sound.

[steve_dave]

Originally Posted by Blu Titan

True enough DD+ was band aid trying to hide one of HD DVD's major flaws.

Blu-ray Disc supports Dolby Digital Plus but because its an optional codec not a standard, studios who use Dolby Digital Plus still need to provide a Dolby Digital track.

So very few Blu-ray Discs have Dolby Digital Plus because its a redundant codec that uses disc space. They instead choose to go with a lossless codec that would provide better sound that is truly sonically different.

[Anthony P]

The main reason for HD-DVD using DD+ was that DD was limited to a bitrate of 448kbps on HD-DVD just like it was on DVD. BD doesn't have that resriction. On BD Dolby labs was able to use DD at the full bitrate of 640kbps for the very first time

it is actually 504kbps for HD DVD, DVD was 448kbps, it is the same issue (both HD DVD force DD in the MPEG-2 stream) but due to the different structure it could go a bit higher on HD DVD

Blu-ray Disc supports Dolby Digital Plus but because its an optional codec not a standard, studios who use Dolby Digital Plus still need to provide a Dolby Digital track.

So very few Blu-ray Discs have Dolby Digital Plus because its a redundant codec that uses disc space. They instead choose to go with a lossless codec that would provide better sound that is truly sonically different.

DD+ can have some advantages over DD and it can be used on BD. The issue is that for standard (26/48 5.1 or 24/48 5.1) it just takes a bit more BW for the same quality. Also since BD splits out the DD and the extra for DD+ BD cannot use DD+ unless it ggets out of DDs capabilities like 7.1 where the 5.1 will be in DD and DD+ will only have the extra 2 channels.

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so to get to the original question, they are exactly the same thing