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Old July 24th, 2013, 04:47 AM   #1
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High Bit Rates, Necessary Or Not?

I often wonder whether or not a high bit rate, say I-Frame 180 Mbps, makes any meaningful difference to a lower rate as far as my requirements go.

I shoot 1080p25 via an EX3. Edit in FCPX. Upload bits to YouTube. Make Blu-Rays for own and friends "consumption" and occasional small scale public "screenings" via my 1080p projector and 100 inch screen.
Will also from time to time use "uncompressed" FCPX edited movies ex my Mac Book Pro as source for viewing or projection rather than a BD.

Am I getting anything from a high bit rate? I appreciate that if I was aiming at "broadcast" or "film" there would be several stages to go through in the editing process that would take advantage of a higher, initial, bit rate.

Maybe there is or are, I-Frame and Long GOP, bit rates that would be the optimum for what I am after.
If these were able to save disc space and editing "clog" so much the better.

Ron

PS after what, three years with my nanoFlash I still can't get over what a wonderful little box of tricks it is.
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Old July 24th, 2013, 11:46 AM   #2
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Re: High Bit Rates, Necessary Or Not?

My feeling is that for 80% of what is being shot with an EX camera, there is no need to go above 50Mbps long-gop 422 recording.
Whenever I do green screen I'll go 100Mbps LongGop.
I rarely need to go above that.
Occasionally a client will want I-frame, and then I'll go 180.
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Old August 3rd, 2013, 10:04 AM   #3
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Re: High Bit Rates, Necessary Or Not?

Convergent Design did a lot of research on this and got an independent assessment done. The conclusion was that it's all but impossible to see any difference in the image quality above 100Mb/s with Mpeg2 long GoP. Between 50 and 100Mb/s the difference was slight, but perceivable. 100Mb/s long GoP holds up better than 50Mb/s to heavy color grading as it has less mosquito noise and fewer artefacts.

From using the NanoFlash a lot this would be my conclusion too.
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