- October 17, 2014 at 5:04 am
MPEG2 codec with GOP settings:
M frames: 3
N frames: 4 for IBBPIBBPIBBP…
Closed GOP every: 4 (or possibly a multiple of 4)
The other settings are marked accordingly.
- October 17, 2014 at 5:06 am
Thanks Ivan –
Just so I understand it a better – can you point to a resource that explains what you just wrote with details?
- October 17, 2014 at 5:12 am
Refer to “Video Export Settings”
- October 17, 2014 at 5:15 am
My apologies –
I read through that earlier – and just took a second look.
What I meant is how does your 2/4 Closed 4 recommendation = IBBP (as opposed to just leaving it at the default 3/15 Automatic GOP placement?
- October 17, 2014 at 5:49 am
Sorry, I made a mistake in the previous post. Been a while since I used MPEG2. I will edit the post shortly.
M = Number of B frames between I/P frames. For IBBP, M=3 produces a P or I-frame every third frame. The minimum is M=1, which corresponds to zero B-frames.
N = Number of frames between I frames. N=4 produces IBBPIBBPIBBP… Setting N=15 produces IBBPBBPBBPBBPBP as a group of pictures. Your spec doesn’t state GOP length. Admittedly, 4 is pretty short, and a number about half the frame rate is more common. Setting N=15 instead of a multiple of 4 (such as N=16) just changes the last frames in the group from BBP (16) to BP (15).
- October 17, 2014 at 5:51 am
Copy that. That makes more sense. Many thanks.
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