On 28/06/2024 14.42, Richard Bartczak via ffmpeg-user wrote:
Hello,
nothing I have found. Neither via ffprobe, nor via ffmpeg, I have found
a solution.
A solution to what, Gloster? What are you trying to solve?
I'll give my latest take on IDR frames: They don't exist, per se. What I think an IDR frame is, is
an ordinary I-frame, open or closed GOP, that follows a closed GOP.
closed GOP _____ _________ An IDR frame
DTS order ..B B P I P B B P..
^^^^^
open GOP _____ _________ Not an IDR frame
DTS order ..B B I P B B P..
^^^
The difference is here
Now, in MPEG-2 TSes, there may be an MPEG tag that forces the previous GOP to _become_ a closed GOP,
but I doubt it because that would require all decoders to buffer all B-frames up to the next P- or
I-frame and to then throw them away if the next I-frame said "IDR"! That defeats the purpose of open
GOP, and, besides that, what's on the screen in the meantime? Nothing? A picture repeat? No, no, no.
Yesterday I read that mastering authors are recommending that open GOP be avoided so that all
I-frames are automatically IDR frames.
It looks to me that MPEG has produced another dog's breakfast.
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