[FFmpeg-user] How to make IDR cuts

[jim shupert]

yes , sorry.
thanks for noticing
We are not sure what happened there.
The current theories are:
1. something super natural
2. I am new to email
3. I was sleepy
;)

cheers

On Sat, Apr 20, 2024 at 7:42 PM David Niklas via ffmpeg-user <
ffmpeg-user at ffmpeg.org> wrote:

> Just a quick heads-up, you seem to have forgotten to put any text in your
> message, Mr. Shupert. It just quotes mark's email.
>
> You're welcome,
> David
>
> On Sat, 20 Apr 2024 17:26:20 -0400
> jim shupert <shupert.jim at gmail.com> wrote:
> > On Wed, Apr 3, 2024 at 8:02 AM Mark Filipak <markfilipak.imdb at gmail.com>
> > wrote:
> >
> > > Is there more to this? If there is, it's not evident to me.
> > >
> > > If there are several B-frames in a row, then adjust your mind to 'see'
> > > larger shifts across the
> > > multiple B-frames and adjust PTSs & DTSs to match.
> > >
> > >
> > > Cutting off a leading open GOP:
> > >                  <————open GOP————>  <—————closed GOP——————>
> > > PTS order      [_I_][_B_][_P_][_B_][_I_][_B_][_P_][_B_][_P_][_I_]
> > >                __/  ___¦___/  ___¦___/  ___¦___/  ___¦___/  __/
> > >               /    /   ¦     /   ¦     /   ¦     /   ¦     /
> > > DTS order [_I_][_P_][_B_][_I_][_B_][_P_][_B_][_P_][_B_][_I_]
> > >              X    X    X         X
> > >
> > > PTS order                          [_I_][_B_][_P_][_B_][_P_][_I_]
> > >                                    __/  ___¦___/  ___¦___/  __/
> > >                                   /    /   ¦     /   ¦     /
> > > DTS order                     [_I_][_P_][_B_][_P_][_B_][_I_]
> > >
> > > Cut on PTS, then fix up the 1st DTS & packet SCRs.
> > >
> > > Or, I don't think it's going to hurt anything to leave this:
> > > PTS order                          [_I_][_B_][_P_][_B_][_P_][_I_]
> > >                               _______/  ___¦___/  ___¦___/  __/
> > >                              /         /   ¦     /   ¦     /
> > > DTS order                [_I_]     [_P_][_B_][_P_][_B_][_I_]
> > > and just fix-up the packet SCRs.
> > >
> > > =====
> > > Cutting off a leading closed GOP:
> > >                  <—————closed GOP——————>  <————open GOP————>
> > > PTS order      [_I_][_B_][_P_][_B_][_P_][_I_][_B_][_P_][_B_][_I_]
> > >                __/  ___¦___/  ___¦___/  __/  ___¦___/  ___¦___/
> > >               /    /   ¦     /   ¦     /    /   ¦     /   ¦
> > > DTS order [_I_][_P_][_B_][_P_][_B_][_I_][_P_][_B_][_I_][_B_]
> > >              X    X    X    X    X
> > >
> > > PTS order                               [_I_][_B_][_P_][_B_][_I_]
> > >                                         __/  ___¦___/  ___¦___/
> > >                                        /    /   ¦     /   ¦
> > > DTS order                          [_I_][_P_][_B_][_I_][_B_]
> > >
> > > Just cut it and fix-up the packet SCRs.
> > >
> > > =====
> > > Cutting off a trailing GOP from a closed GOP:
> > >                  <—————closed GOP——————>
> > > PTS order      [_I_][_B_][_P_][_B_][_P_][_I_]..
> > >                __/  ___¦___/  ___¦___/
> > >               /    /   ¦     /   ¦
> > > DTS order [_I_][_P_][_B_][_P_][_B_]
> > >
> > > Just cut at the end of the closed GOP.
> > >
> > > =====
> > > Cutting off a trailing GOP from an open GOP:
> > >                  <————open GOP————>
> > > PTS order      [_I_][_B_][_P_][_B_][_I_]..
> > >                __/  ___¦___/  ___¦___/
> > >               /    /   ¦     /   ¦
> > > DTS order [_I_][_P_][_B_][_I_][_B_]
> > >
> > > PTS order      [_I_][_B_][_P_][_B_][_I_]
> > >                __/  ___¦___/  ___¦___/
> > >               /    /   ¦     /   ¦
> > > DTS order [_I_][_P_][_B_][_I_][_B_]
> > >
> > > Cut retaining an ending I-frame, only.
> > >
> > >
> > > Honestly, I don't know why the MPEG folks don't supply illustrations
> > > instead of their torturous text.
> > >
> > > This isn't magic, it's Legos.
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