Format Neutral Studios like Warner, Paramount etc sometimes give a plain Dolby Digital 5.1ch Surround @640 Kbps treatment to BD whilst the HD DVD gets a Dolby Digital-Plus 5.1 surround @1.5mbps track.

Any technical / political reasons behind this ?

Format Neutral Studios like Warner, Paramount etc sometimes give a plain Dolby Digital 5.1ch Surround @640 Kbps treatment to BD whilst the HD DVD gets a Dolby Digital-Plus 5.1 surround @1.5mbps track.

Any technical / political reasons behind this ?

political. Both were going to be HD DVD exclusive studios, and while they are neutral now, they are still biased against Blu-Ray.

http://www.avsforum.com/avs-vb/showthread.php?p=8185848&&#post8185848
Basicly both format get screwed out of sound quality.

But thouse studios always did that on DVD so that comes as no suprise.

With Warner, their DD tracks on BD are identical to their DD+ tracks on HD DVD. The problem with that studio is the inclusion of lossless audio (or lack thereof) on some titles that got it on HD DVD, but Warner seems to have stopped downgrading the audio for Blu-ray.

Paramount on the other hand downgrades every single Blu-ray Disc in the audio department, as you said. This is at least partly due to the fact that it is not mandatory for Blu-ray players to decode Dolby Digital-Plus, and so far none of them do. However, there is nothing stopping them from including a PCM track or something along those lines on most releases since each of their encodes is tailored specifically to Blu-ray spec, so there ought to be room for it as long as the video isn't already bit-starved (especially if a 50GB disc is used, as is often the case).

So, Paramount could have done many things with the audio; such as adding higher-quality audio tracks that Blu-ray is compatible with, or using only the standard Dolby Digital codec at 640kpbs, which subjectively sounds decent compared to the higher-bitrate DD+, if a little worse. Paramount could easily fit in a superior uncompressed audio track on a large number of their Blu-ray discs without paying any additional fees, but for one reason or another they choose not to. (It would be unwise to include just an uncompressed surround track like we saw with The Sopranos, since those without HDMI or 5.1 analog would only get stereo sound.)

That's as far as I can tell, anyway. If I'm mistaken, please chime in.
edit: I noticed a flaw in my own argument in the third paragraph, I have altered it. :o

Format Neutral Studios like Warner, Paramount etc sometimes give a plain Dolby Digital 5.1ch Surround @640 Kbps treatment to BD whilst the HD DVD gets a Dolby Digital-Plus 5.1 surround @1.5mbps track.

Any technical / political reasons behind this ?
Contrary to many Blu-ray fanboys, there are technical reason for this discrepancy.

1. DD+ is not mandatory codec on Blu-ray
2. DD has a maximum bitrate of 640kbps for Blu-ray

Now Warner or Paramount could have included DD+ for Blu-ray, but I don't think any Blu-ray players currently supports DD+, so you would have just gotten DD 640kbps core from higher bps DD+.

Contrary to many Blu-ray fanboys, there are technical reason for this discrepancy.

1. DD+ is not mandatory codec on Blu-ray
2. DD has a maximum bitrate of 640kbps for Blu-ray

Now Warner or Paramount could have included DD+ for Blu-ray, but I don't think any Blu-ray players currently supports DD+, so you would have just gotten DD 640kbps core from higher bps DD+.
I believe you are correct.

Contrary to many Blu-ray fanboys, there are technical reason for this discrepancy.

1. DD+ is not mandatory codec on Blu-ray
2. DD has a maximum bitrate of 640kbps for Blu-ray

Now Warner or Paramount could have included DD+ for Blu-ray, but I don't think any Blu-ray players currently supports DD+, so you would have just gotten DD 640kbps core from higher bps DD+.

This is the correct answer. It's because Blu-ray players don't support DD+ across the board. However, I see this as an advatage for the future because it forces studios to use Lossless instead of half-assing everything.

Agree, there is space and pcm is "free"

Contrary to many Blu-ray fanboys, there are technical reason for this discrepancy.

1. DD+ is not mandatory codec on Blu-ray
2. DD has a maximum bitrate of 640kbps for Blu-ray

Now Warner or Paramount could have included DD+ for Blu-ray, but I don't think any Blu-ray players currently supports DD+, so you would have just gotten DD 640kbps core from higher bps DD+.

DD+ on BD is only for soundtracks with more than 5.1 channels.

The Panasonic, LG and new Samsung player support DD+ for BD.

DD+ is a better codec than DD and it is running at up to 3,000 k, compared to 640 k DD on Blurray.

Response by Roger Dressler of Dolby Labs

Sorry to burst the bubble on that one.

Bubble fully intact. Myth exploded. No one is using 3 Mbps, and the maximum datarate capability has no bearing on how it sounds at a lower bitrate, like 640 kbps for example.

DD+ exist for two reasons:
1. Because of HD DVD limitations it can not do DD at 640kbps.
2. DD is limited to 6 channels.

The studios need to take a tip from Disney: many of their titles are 24 bit PCM (and it's still reported that the DTS MA tracks from Fox/MGM are 24 bit as well). They don't HAVE to use PCM... they could use Dolby TrueHD (without Dial. Norm.!!!) at 24 bits, or they could use DTS MA. The only problem with the latter format is that there is no way to hear it easily right now (no players on either side have it), whereas Dolby TrueHD is decoded in at least two Blu-ray players and many HD-DVD players.

Dan