On 17/06/2024 18.05, Paul B Mahol wrote:
On Tue, Jun 18, 2024 at 12:00 AM Mark Filipak <markfilipak.i...@gmail.com>
wrote:
On 17/06/2024 17.18, Paul B Mahol wrote:
On Mon, Jun 17, 2024 at 8:29 PM Mark Filipak <markfilipak.i...@gmail.com
wrote:
On 17/06/2024 13.50, Paul B Mahol wrote:
On Mon, Jun 17, 2024 at 5:35 PM Mark Filipak <
markfilipak.i...@gmail.com
wrote:
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.
PTS order is order once frames are decoded and going to be presented to
user, thats why it is called presentation timestamps.
Yes of course.
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?
If decoder follows specifications for decoding bitstreams correctly
than
changing order of raw encoded frames as stored in bitstream will almost
every-time cause broken decoding.
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.
If this is at format container layer, I dunno how would that work even
if
its is possible to be useful.
The container would contain a PES packet stream with PCRs like any other
PES packet stream. It would
work like any PTS-ordered stream does. You know, there _are_ PTS-ordered
streams. And you know, MPEG
is silent on the matter of what physical order frames are in the stream,
only that they must be
given to the decoder in DTS-order.
Look, I agree that it would be nonsense. I want to turn the DTS-ordered
stream into a PTS-ordered
stream merely as a test: '-f show_frames' appears to be getting DTSes
and
PTSes mixed up, then
applying a fix that results in completely new DTSes. If it treats the
PTS-ordered stream
differently, that will say a lot. What is says depends on what it does.
Capiche?
I thought I could do it by demuxing, then moving them like you can move
frames in a filter_complex,
and then remuxing, but I don't know how to do that to PES packets
(instead
of decoded pictures) and
I don't know how to rewrite PCRs.
But aren't you working with HEVC and not MPEG video?
I'm working with AVC-M2TS, then transcoding-remuxing to HEVC-MP4.
So you operate with bsf filters to create HEVC output?
No. Let me explain.
My original project is to edit and join the 4 episodes of Bergman's FANNY OCH ALEXANDER (5h11m).
That's going to be HEVC-MP4 -- actually I've already done it but it has gaps at the splices. For
that Bergman project I transcode of course.
I had very carefully planned out the 7 cuts and 3 IDR splices using '-bsf noise' and '-bsf setts'. I
have the scripts (Windows) if you care to see them -- if I may say so myself, they're quite elegant.
Of course, I tried to use '-ss' and '-to' at first, but they made a mess.
By the way, '-i "concat:...|..."' is not the problem many people think it is. The problem is
actually the timestamp bug I found.
Okay, back to the subject: I found the timestamp bug and clipped out a 4 second sample that spans
the first splice. That's what I gave to trac. It is AVC-M2TS, the same as the Criterion original.
It's for test cases of that 4 second sample that I want to create a PTS-order version.
I hope that's clear, now. I apologize for the confusion.
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