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Getting my head round picture resolutions

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Peter Groom
Getting my head round picture resolutions
on Jan 9, 2014 at 2:27:04 pm

A little guidance / clarification.

When i import / transcode etc all media, clearly users have to specify a picture resolution. I usually go for 185. Problem is I dont really know why!

I shoot on ex1 at 35mbps etc etc and I want my media available at the highest picture quality at all times. i dont mind about drive space as theres loads available, but Im unclear as to wether Im using drive space at 185 , that isnt necessary with that source footage.
I wouldnt even mind going uncompressed if it gave a visible advantage, but not if it isnt actually visible?
I just dont want to lose anything visibly.

Any thoughts?
Peter

Post Production Dubbing Mixer


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Michael Phillips
Re: Getting my head round picture resolutions
on Jan 9, 2014 at 6:58:04 pm

The first difference is the fact that you are shooting long GOP MPEG encoding and transcoding to an I frame codec like DNxHD. Because of the differences in encoding, you cannot just match up data rates and think they are the same (not saying you are, just setting the ground rules). MPEG encoding can maintain a higher quality picture at much smaller data rate but can suffer from image control and multi-generation depending on what you want to do with it.

I find that with EX1 going to DNxHD 145 is fine more most if not all transcodes. You are not gaining any additional quality by going higher or uncompressed. The EX1 is also 8 bit as is DNxHD 145. You can keep going to 185x (10 bit) if you want, the 10 bit will give you slightly more control (not more color) when doing certain color correction operations.

Michael


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Pat Horridge
Re: Getting my head round picture resolutions
on Jan 10, 2014 at 9:22:04 am

Working in 10bit is only useful if you then retain 10bit all the way to delivery. Grade at 10bit and output to an 8bit format and you lose all you gained.
Also not keen on 185x as it has the same data rate of 185 at 8 bit so for 10bit its more compressed.

Pat Horridge
Technical Director, Trainer, Avid Certified Instructor
VET
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T +44 (0)20 7505 4701 | F +44 (0)20 7505 4800 | E pat@vet.co.uk |
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