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Old 25th October 2009, 00:43   #61  |  Link
nm
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Join Date: Mar 2005
Location: Finland
Posts: 2,641
Quote:
Originally Posted by popper View Post
what i get from that page
http://tom.niko.users.sbb.rs/gop.jpg
seems simple enough, and we are talking about trying to make it as easy as possible, so as to try and help everyone actually visualise the intent of the spec.

is:

it doesnt matter if there are no widspread i50 or i60.
You are pointing to a draft document that specifically defines the allowed framerates for Blu-ray. Interlaced 50 or 60 frames/s video is not allowed.

Quote:
the Only thing that matters is:
that IF your bitrate is 15Mbit/s or less then you Can use a 2 second GOP IF you want to, but you dont have to, you can still use a 1 second GOP if you like.

to get a --keyint value you do the SIMPLE THING, if its Less than 15Mbit/s you simply take the FPS or 'frame rate value[Hz]' if you prefer calling it that , round it up* to the nearest int, and then double it.

if its More than 15Mbit/s then you Do NOT double it, but rather just use the nearest rounded up int of the FPS/'frame rate value[Hz]'.
Yes, but the spec still defines the rates that you are allowed to use for each interlaced and progressive frame format.

Quote:
so your i50 or i60 (or even p50 p60) would use a --keyint value of 100 and 120 If their bitrates were 15Mbit/s or less, or 50 and 60 if they were using faster bitrates!
Interlaced video at 50 or 60 frames/s is not allowed, only 720p50/60 is.

Quote:
now we Might have a slight problem here, in that if your after Encoding a future SD/HD high speed camera footage to 15Mbit/s or less, with an FPS of something like >1200 fps at QVGA.
What problem? The current broadcast and disc formats don't allow such framerates so you are free to use whatever keyint you want for such a non-standard encode.

If high-speed footage is used in some standard production, it is either played back in slow motion or frames are skipped or combined.

Man, I wish interlacing would die already.
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