AC3 encoding in Protools?

[richdef1]

Hi guys, just need to pick the brains out there:
I am mainly a TV and Film sound editor, so I don't normally get involved in mastering, but I am involved in an AV project that requires AC3 encoding and a Mix in situe... my question is this, is there an AC3 plugin for Protools that dosen't cost the earth, and can it output the encoded signal live though an optical output on an interface, I mainly use a 002 rack for AV work. I know you can render AC3 in Final cut.

[Pete Gates]

Hi Richard,
How's it going? I've got the Neyrinck AC3 plugin - I can put it on a spare ilok and lend it to you if you want. http://www.neyrinck.com/en/products/dolby-digital

It does realtime decode but I seem to remember that the encode is audiosuite only - but faster than realtime. Not used it for ages so check the website!

Pete

[richdef1]

Cheers Pete!

I was just there on the website myself, I already have 'SoundCode Stereo'
So looks like a $249 upgrade for LTRT. Can't see if you can output encoded though still.

[richdef1]

Sorry I was looking at the wrong plug in, I can see the AC3 now and it is only Audio suite, but has got me wondering if the Pro Logic™ II plug in 'SoundCode Stereo LtRt' will give a real time optical encoded output.... that is of course if the client will accept Pro Logic™ II?.... the issue is the client wants the job mixed on the installation hardware.

[Postman]

Hi,

AC3 is entirely different than LtRt. Pete gives a link to the SoundCode product you could use for your AC3 encoded output (SoundCode for Dolby Digital). Neyrink named the product after Dolby Digital, which is a 5.1 channel subset of AC3 encoding. In fact SoundCode for Dolby Digital does any form of AC3 encoding you are likely to encounter. An AC3 file is data that must be decoded in order to be heard as audio.

LtRt encoding, which you have in SoundCode for Stereo, is a way to squish LCRS or 5.1 channels down to a two channel "matrixed" version that is compatible with standard stereo...you can listen to it after encoding. Unlike AC3, when the two channels are decoded to surround you don't get back what you put in. You get a re-interpretation. Among other things you get a center channel whether you originally had one or not and what goes to the surround channel(s) can be radically different than where you started.

[Postman]

You posted while I was composing...

Both LtRt and AC3 are transmitted as two channels of data, so either can be fed through a typical optical output. But, as I said, they are very different.

I think with Neyrink's SoundCode for Dolby Digital, you would have to encode as audiosuite process, which would save as an AC3 file. You could import that file exactly as if it was audio (assuming you maintain its bit depth) and run it in realtime from Pro Tools. But, you would not be able to make changes to your Pro Tools mix "live" and hear it reflected in the AC3 data stream.

[richdef1]

Thank you both, food for thought. will let you know how it pans out. (excuse the pun)