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Old 12th August 2012, 17:26   #1  |  Link
Beak
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CRF Question

I have just installed a Bluray burner in my machine.

I have a 36 Gig m2ts file that has to shrink to 23 total.

I am hoping someone could suggest a CRF number that will get me around 20 gigs plus/minus.

I am hoping to avoid the time 2 pass encoding take as I have a fair number of filters slowing me down.

Any help would be appreciated.
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Old 12th August 2012, 18:03   #2  |  Link
Sharc
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As you can read from many posts in this forum it is pointless to expect a certain file size by selecting a certain CRF - not even approximate. For a given CRF the file size depends on the complexity of the pictures (motion, details, noise, your filters, etc) and will accordingly vary significantly.
If you want a certain size you need to go for 2-pass.

Last edited by Sharc; 12th August 2012 at 18:05.
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Old 12th August 2012, 23:28   #3  |  Link
sneaker_ger
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or 1 pass ABR
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Old 13th August 2012, 17:30   #4  |  Link
Beak
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The bitrate calculator has made a CRF estimate that seems OK. I realize it will miss the target size if the movie is complex but its working well so far,

I'll try ABR at a bitrate of 20900. That should hit the filesize and seems to be a good enough bitrate to ensure good quality.

Thanks to those who helped.
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Old 13th August 2012, 17:36   #5  |  Link
Groucho2004
 
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Quote:
Originally Posted by Beak View Post
I'll try ABR at a bitrate of 20900.
Don't.

Also, the time you need to figure out the correct CRF value for your target size is probably longer than a good old 2 pass encode.
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Old 18th August 2012, 02:38   #6  |  Link
blubb444
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If you're really using an extremely slow script (for example QTGMC at "placebo" on a 1080i source) then you might consider to first encode your script to lossless (for example --preset fast --qp 0, you can of course use faster presets too) and then run a 2-pass on that file.
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