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  #1  
Old 01-06-2012, 11:26 AM
garnoil garnoil is offline
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Default Is the quality of a "ripped" AC3 good enough to lay back to HD Cam

I was asked today if the 5.1 sound on a DVD can be ripped into 6 discrete channels as the distributor requires HD cam SR. A distribution company I am working with is re-issuing and older film and all they have is the sound of the film as it exists in the original release of the film on DVD in surround 5.1 (they don't have the master 5.1 sound prior to the AC3 encode or the master PT sessions).

BTW, this is all 100% legit, the distributor/producers have all the rights to the film (it is their film) it is not like they are trying to illegally rip off a feature film.
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Old 01-06-2012, 11:29 AM
tom_lowe tom_lowe is offline
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Default Re: Is the quality of a "ripped" AC3 good enough to lay back to HD Cam

Quote:
Originally Posted by garnoil View Post
I was asked today if the 5.1 sound on a DVD can be ripped into 6 discrete channels as the distributor requires HD cam SR. A distribution company I am working with is re-issuing and older film and all they have is the sound of the film as it exists in the original release of the film on DVD in surround 5.1 (they don't have the master 5.1 sound prior to the AC3 encode or the master PT sessions).

BTW, this is all 100% legit, the distributor/producers have all the rights to the film (it is their film) it is not like they are trying to illegally rip off a feature film.
Well considering it will be re-encoded to DD or MPEG audio if it ever gets broadcast, it will sound terrible. Why don't have have the originals?!
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Old 01-06-2012, 11:40 AM
garnoil garnoil is offline
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Default Re: Is the quality of a "ripped" AC3 good enough to lay back to HD Cam

Yes, I agree, this is exactly what I suspected. I don't know why they do not have the originals, I am told that hey do have the M&Es and the LTRT but not the master 5.1...strange!
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Old 01-06-2012, 12:48 PM
SBP SBP is offline
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Default Re: Is the quality of a "ripped" AC3 good enough to lay back to HD Cam

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Originally Posted by garnoil View Post
I was asked today if the 5.1 sound on a DVD can be ripped into 6 discrete channels as the distributor requires HD cam SR.
Probably confirming what I think you already know here .......

I would say while it is possible to do this it is not good practice.

The expectation when requesting/receiving audio discrete on a HDcamSR is that the material is 'un compressed full bandwidth'

This material will have had data reduction to 448kbps as part of initial Ac3 encode and so could not be considered 'un compressed full bandwidth'.

My understanding of Ac3 is that it was not designed for several encode/decode passes -like Dolby E -but as a final delivery codec ie encode once, decode once.

Anyway I guess best to inform your client -get them to check delivery specs, and let them decided what they want to do. Probably be worth having a listen to the material after it has been re-encoded to Ac3 again -to see what the result is.

All the best

Bruno
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Old 01-06-2012, 02:06 PM
matt-o- matt-o- is offline
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Default Re: Is the quality of a "ripped" AC3 good enough to lay back to HD Cam

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Originally Posted by garnoil View Post
I am told that hey do have the M&Es and the LTRT but not the master 5.1...strange!
try to decode the LtRt and use LCR from this and combine with the surrounds and LFE from the M&E... may be better there are less trade-offs than AC3....

maybe even keep only the C for dialogue and mix with the other five M&E channels...


just an idea...
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Old 01-06-2012, 02:53 PM
garnoil garnoil is offline
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Default Re: Is the quality of a "ripped" AC3 good enough to lay back to HD Cam

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Originally Posted by matt-o- View Post
try to decode the LtRt and use LCR from this and combine with the surrounds and LFE from the M&E... may be better there are less trade-offs than AC3....

maybe even keep only the C for dialogue and mix with the other five M&E channels...


just an idea...
Thanks for the suggestions. The producers will decide on what is best but given what they have it may be easier to re-mix from the very original OMF and create brand new sound track.
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Old 01-07-2012, 04:03 PM
mr.armadillo mr.armadillo is offline
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Default

Wow. Easier to remix from original omf?!
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  #8  
Old 01-09-2012, 12:50 PM
georgia georgia is offline
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Default Re: Is the quality of a "ripped" AC3 good enough to lay back to HD Cam

Use the LtRt and M&Es to recreate....

an AC3 encoded, decoded, encoded and decoded once again is going to sound like crap.. That's why they have DOLBY E, so you can encode and decode as many times as you want.

cheers
geo
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  #9  
Old 01-09-2012, 02:08 PM
Tstein Tstein is offline
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Default Re: Is the quality of a "ripped" AC3 good enough to lay back to HD Cam

Another vote against AC3. Be careful when combining LtRt and other stems. Make sure that phase alignment is spot on and check stereo & mono down mixes.
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