On 17/06/2024 03.16, Paul B Mahol wrote:
On Mon, Jun 17, 2024 at 3:16 AM Mark Filipak <markfilipak.i...@gmail.com>
wrote:
To expand on my idea:
The video is this:
I P B B P B B P B B I P B B..
I want to change it to this:
I B B P B B P B B P I B B P..
If this is what I think it is, your are wasting your time.
It is possible. But can FFmpeg do it? You see, Paul, I read in several places from seemingly
authoritative people that professional videos are PTS-ordered. I've since discovered that
professional videos are almost always DTS-ordered -- I now have a packet browser and have seen it to
be true. However, I have seen professional videos that are PTS-ordered but I didn't think too much
about it at the time.
My idea is to take the 4-second video -- DTS-ordered -- that I sent to trac, change it to
PTS-ordered, and see if '-vf showinfo' and '-f show_frames' respond correctly. It's a long shot, but
it might show something useful -- what if PTS-order made showinfo show_frames and framecrc all
agree? Wouldn't that be something interesting?
Its nonsense to change order of encoded frames, no manipulation of clock
can fix that.
No, no. Manipulation of PCR. Fix up the PCRs so that the result is truly
PTS-ordered.
When doing concat you can not concat in middle of group of frames.
I'm not doing that.
Each beginning and end frame must be the key-frame.
Of course.
To do that, I reckon I need to,
1, move the packets that contain P-frames,
2, insert revised 'program_clock_reference_base's and
'program_clock_reference_extension's into each
of them to account for the new order, and
3, do some packet fixup (maybe).
Is that possible with FFmpeg?
--Mark.
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