iTunes requires surround upmix for HD material?

[Brian Cares]

Hi post forum,

I mixed a feature film for DVD and movie theatre last year in stereo.
The client now wants to put this film on iTunes in HD.

He quoted me this line from iTunes:

"We can deliver HD to iTunes but the audio needs to be mixed to 8 channels. L, R, C. LFE, LS, RS, Lt, Rt. This is an iTunes requirement."

Does this mean the stereo has to be upmixed to 7.1 surround?

As i am totally not into surround i have no idea how complicated and expensive such an upmix processing would be.
I remember seeing such a service in the NewProducts section but cant remember the name or tag.

Would you be so kind to enlighten me on this topic?
Any input is appreciated.

[pneyrinck]

The spec calls for a 5.1 mix and a stereo LtRt mix. Ideally, you would go back to your original stereo mix project and remix it for 5.1. There are some great upmixing tools these days to go from stereo to 5.1 but if possible you should make a real 5.1 mix so you have complete control of what plays in the front, center, surround, and LFE channels.

[Jesse Peterson]

I would double check with this, but with itunes if the source is stereo that can be specified. The requirement assumes a surround mix and multi track tape delivery. Have the producers confirm with the apple people or whoever the distro is.

the requirement does not mean 7.1 - it means 5.1 on 1-6 and encoded LtRt on 7-8. In simple terms, LtRt is a matrixed stereo-ish version of a surround program that uses phase relationships that a decoder can understand and use to steer sound to the center and rear speakers.

When you send a true stereo mix through the decoder, anything that is dead on mono will go to the center, anything that is ultra wide stereo will be sent to the rear.. everything that lives in the middle of these extremes will placed around the room based on the width of the stereo

[Brian Cares]

Ah right. I see.
Thanks for the reply.

Well, doing the 5.1 mix myself is not an option as i have neither the equipment nor the knowledge to do this.

The film is a "rockumentary" with interviews and live footage recorded in stereo and sometimes just main feed and cam atmo. So there is no real need of mixing in 5.1.

Is there a cost efficient way to just get a basic 5.1 upmix done for a reasonable price, just to meet the iTunes specs? I could see someone just running the stereo mix through one of these boxes as a service.

[Smallbudgetguru]

When I buy a documentary on musicians. I am very happy when they send a little music through surrounds. I would not say that due to the nature of your programme surround won't make your audience happy.

[iluvcapra]

Originally Posted by Brian Cares

Ah right. I see.
Thanks for the reply.

Well, doing the 5.1 mix myself is not an option as i have neither the equipment nor the knowledge to do this.

The film is a "rockumentary" with interviews and live footage recorded in stereo and sometimes just main feed and cam atmo. So there is no real need of mixing in 5.1.

Is your stereo mix an LtRt, or just Left-Right (LoRo)? If it was LtRt, you should be able to decode through the Dolby plugin (you can rent it for a day for like $30) and that'll give you an LCR with mono surround, that you can strap or pan center to the stereo surrounds (I forget which one you're supposed to do ) I'd probably leave the LFE empty, though I bet some people here have differing opinions on that.

If you mixed it LoRo, I'd strongly advise listening to it once through a Pro Logic receiver with proper surrounds, because a lot of popular music uses spatializers and phasing which might be incompatible with an LtRt, and should be checked. You can also see this on output meters from a Dolby decoder plugin -- if you get to a particular song and see the surround channel going crazy, this is probably a bad sign.