Dolby Question...

[showstopper168]

Hi everyone,
Just wondering if you do encoding using the Dolby encoder plug in (DVD release) and also using the Dolby AC-3 file for your DVD release...do you need to give licensing fee and what not to Dolby? Thanks!

[Bill@AudioVision]

Generally not. You paid for a license to Dolby when you purchased the software. To save money, it will be feature limited compared to a regular Dolby product, and even then, you pay once when you purchase the software. All DVD manufacturers pay Dolby for the use of the decoding software in each player. Unless you are talking a feature release, you don't need to worry per project.

[showstopper168]

Get it! Thank you very much Bill. another Q...After delivering the 5.1 stems and LtRt stems....what is the nest step? how do you manage to put those files in to a DVD....do you either choose one kind of file or....always curious about what they do next for the stems when they do a DVD release. Thanks a lot!

[pneyrinck]

It is correct that you do not have to pay Dolby any licensing fees to use Dolby Digital on a DVD. But if you want to display the Dolby Digital logo on your DVD package artwork, then you need to apply for their Logo Use Agreement. Go to Dolby's website for more information. Dolby - Dolby Logo Use Agreement Application

The basic workflow for DVD is:

1. Make the 5.1 mix
2. Measure the dialnorm (or adjust the mix to meet a target dialnorm)
3. Encode the AC3 file
4. Test the AC3 file
5. Import the AC3 file into a DVD authoring application.

Note that you do not need to encode separate 5.1 and LtRt AC3 streams. If you encode a 5.1 stream, every DVD player is capable of downmixing to stereo.

Paul Neyrinck
Neyrinck Audio

[JoeMilner]

Hi Paul, sorry to jump in, but I get the "auto-downmix " question a lot, and wanted to clarify; the 5.1 gets auto-downmixed in the player to Lo/Ro stereo, right? Not an actual Lt/Rt?

Thanks

Joe

[georgia]

It can play back from AC3 5.1 to L C R S or L R or Mono. it all depends on the systems ability and available playback formats.

example: I have a Harmon Kardon system and I receive the DTS or DOLBY 5.1 signal optically from the DVD player. The Harmon Karodn home system decodes the AC3 into discreet channels as appropriate by my selection on the front panel. I can select to listen in 5.1, LCRS, Stereo or Mono. If I listen to my DVD player directly off my TV, I get essentially an stereo signal downmixed from 5.1. Lo/Ro is a True L only R only stereo mix. Lt/Rt (L total / R total ) is an encoded mix from L C R S. A 5.1 AC3 mix can be downmixed to L C R S but it isn't an Lt/Rt mix.

cheers
geo

[thierryd]

Originally Posted by georgia

It can play back from AC3 5.1 to L C R S or L R or Mono. it all depends on the systems ability and available playback formats.

example: I have a Harmon Kardon system and I receive the DTS or DOLBY 5.1 signal optically from the DVD player. The Harmon Karodn home system decodes the AC3 into discreet channels as appropriate by my selection on the front panel. I can select to listen in 5.1, LCRS, Stereo or Mono. If I listen to my DVD player directly off my TV, I get essentially an stereo signal downmixed from 5.1. Lo/Ro is a True L only R only stereo mix. Lt/Rt (L total / R total ) is an encoded mix from L C R S. A 5.1 AC3 mix can be downmixed to L C R S but it isn't an Lt/Rt mix.

cheers
geo

Georgia, I always understood that you can select the 5.1 downmix to be preferably LtRt or LoRo (using the BSI extension with extra info).
With a LoRo setting the stereo isn't touched and just played through 2 L R speakers.
The LtRt setting is more complex. I don't think that a 5.1 ac3 can be downmixed directly to LCRS, unless it was a 4.0 (LCRS config) to begin with. Maybe your HK has a special downmix mode like that, which would mean it combines the LsRs of the 5.1 to S and adds the .1 to the mains or leaves it LFE.
Where it gets really confusing is how the 5.1 gets to an LtRt signal. You can select the surround channels to be 90 degree phase shifted (which is also done in a normal LCRS to LtRt encoding), but I don't think the DVD player or hometheater can do the Dolby noise reduction encoding and 7kHz filtering that normally happens in a LCRS to LtRt Dolby Surround encoding. I guess what it can do is a 180degree out of phase encoding for the surround channels channels when downmixing 5.1 to LtRt, but even here I'm not sure.

In a recent conversation with Florian Camerer from ORF, he told me that when the 90degree phase shift is checked during the ac3 encoding, that the surround channels will ALWAYS be 90degree shifted, so also during an ac3 5.1 decode. Until then I thought that the surround channels only got this 90degree phase shift, when a downmix was applied in the DVD player. I don't do ac3 encodings on a regular basis and haven't really checked this after the conversation, but it makes me wonder if it is a good idea to leave this 90degree phase shift on per default. On music surround mixes with lots of phase relationships between front and rear, it certainly doesn't seem like a good idea.

I'm sure all this is more the territory of Paul Neyrinck and DVD mastering engineers and I reserve the right to be absolutely wrong :-)

Greetings,

Thierry

[JoeMilner]

Thanks Georgia!
I definitely know the difference between an Lt/Rt and a Lo/Ro.....and have made that speech to almost every client I've ever had, haha.
Just wanted to confirm what's going on, as I'm always pushing to put the 5.1 mix on the DVD and the clients are like "but what if somebody doesn't have 5.1, OMG!!!" ha

cheers,

J

[showstopper168]

Hey guys, Thanks for the great knowledge!! By the way, if we are able to put the 5.1 stems in to a DVD and they are able to downmix it to LoRo stereo mix right thru your DVD player....what is the purpose of having to encode LtRt stems? Thanks again!

[pneyrinck]

Originally Posted by JoeMilner

Just wanted to confirm what's going on, as I'm always pushing to put the 5.1 mix on the DVD and the clients are like "but what if somebody doesn't have 5.1, OMG!!!"

A DVD player can definitely down mix to an LtRt that can be decoded to LCRS. But a couple settings are required when encoding the AC3:

1. Surround Phase Shift - Enabled
2. Stereo Downmix Preference - LtRt Downmix Preferred

Every DVD player must be able to downmix the encoded 5.1 to stereo using metadata information for the downmix equation. Regrettably, the type is "preferred" and the downmix equation can be for LoRo or LtRt. If it does do an LtRt downmix, PL1, and PL2 decoders will decode it to LCRS (Ls and Rs channels will both have the S channel in them).

Paul

[showstopper168]

Cool! But why do we always deliver the 5.1 stems and also the LtRt Stems...when we already have the privilege to downmix a 5.1 stems to LtRt thru the DVD player?