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Darren 10-11-2007 03:41 PM

Blu-ray Dolby Digital vs HS. DDplus...
I bumped into a colleague who worked QC for some of the bigger studios on HD and BD titles and he had an interesting bit of info to offer. He said that while on titles where there’s a dolby digital plus track on the HD release and only a dolby digital track on the BR, many times, depending on the studio, it’s dolby digital presented at a higher bit rate that is equivalent to DDplus, it just doesn’t have the ‘plus’ branding.

Is this true and does anyone know what bit rates Warners and Paramount encode DD plus for HD DVD and DD for BD?


tigeraudio2007 10-11-2007 04:10 PM

Re: Blu-ray Dolby Digital vs HS. DDplus...
Here is what these formats are capable of...

Dolby Digital on a DVD is capable up to 448kbps.
Dolby Digital on an HD DVD is capable up to 504kbps
Dolby Digital on an Blu-ray is capable up to 640kbps

Dolby Digital Plus on an HD DVD is currently limited to a max of 3.0Mbps
Dolby Digital Plus on a Blu-ray is currently limited to a max of 1.7Mbps

Dolby TrueHD on HD DVD and Blu-ray are both represented at 18Mbps

So yes that 640kbps Dolby Digital track may be present on a Blu-ray. However, it is less than half of what a typical Dolby Digital Plus track offers (typically a minimum of 1.5Mbps).

Hope that clarifies things.

Darren 10-11-2007 04:16 PM

Re: Blu-ray Dolby Digital vs HS. DDplus...

Very helpful info.

Any idea what is actually being used in practice (any examples x title is at xxmbps etc.) vs. the format's capabilities?


Darren 10-11-2007 04:47 PM

Re: Blu-ray Dolby Digital vs HS. DDplus...
Also, do you know what the bit rate is for DTS on standard DVD? Thanks.

tigeraudio2007 10-11-2007 05:17 PM

Re: Blu-ray Dolby Digital vs HS. DDplus...
As for Blu-ray...

300 - LPCM 4608kbps, DD 640kbps, TrueHD 18Mbps
Casino Royale - LPCM 4608kbps, DD 448kbps
Click - LPCM 4608kbps, DD 640kbps

I don't believe that Blu-ray uses Dolby Digital Plus.

I believe that all the HD DVDs thus far have used 1.5Mbps and not the limit of 3.0Mbps. Universal titles are at 1.5Mbps. I'm not sure about WB, but I'm pretty positive they're only 1.5MBps as well. I'll try to find specific examples.

DTS on SD DVD varies as well. The first titles released in DTS on DVD were generally encoded at the highest bitrate for DVD DTS which is 1536kbps. Later titles began to used a reduced bitrate of 768kbps. Jurassic Park would be encoded at 1536kbps whereas I believe Dante's Peak was released with a 768kbps bitrate.

DaViD Boulet 10-11-2007 08:30 PM

Re: Blu-ray Dolby Digital vs HS. DDplus...
IMO, arguing about "lossy" bit-rates and sound quality (and even codecs) is a moot conversation when we can have 24-bit LOSSLESS on either HD medium.

Of course, LPCM on Blu-ray avoids additional processing (ie, bit-altering) steps like the dialog normalization that's incorporated into almost every Dolby TrueHD track on HD DVD (and many on BD).

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