#11080: FFmpeg timestamps do not consistently agree with packet timestamps
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Reporter: markfilipak | Owner: (none)
Type: defect | Status: new
Priority: normal | Component:
| undetermined
Version: unspecified | Resolution:
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by markfilipak):
I'm responding in the order your comments are in...
Replying to [comment:13 Balling]:
> You moved the first two B frames (their display),
I didn't move the first 2 B-frames, I dropped them because they are in the
previous GOP. Here's the script:
{{{
: Cutting out a 4 second clip at the splice +/- 2 seconds.
:
: source is 00305+00306.m2ts
: CUT1 = 1:32:49.814 = 5569.814 sec //running time to starting I-frame
: CUT2 = 1:32:53.818 = 5573.818 sec //running time to ending I-frame
:
: CUT1:
: (5569.814 sec)*(24/1.001 frames/sec) = 133542 frames
: (2854113 ticks)+(133542 frames)*(3753.75 ticks/frame) = 504137395.5
ticks
: = 504137396 ticks
: PTS 504137396 is an I-frame in packet 75943446
:
: step 1: ..________drop________
: \
: PTS order ..P B B I..
: ___________________________/
: /
: DTS order I B B P..
: \ \ \ \
: 504126135 504129888 504133642 504137396
set CUT1=lt(pts\,504137396)
: step 2: rewrite the I-frame's DTS
:
: PTS order I..
: _______/
: /
: DTS order I P..
: \ \
: 504133642 504137396
set IDR=if(eq(DTS\,504126135)\,504133642,DTS)
: CUT2:
: (5573.818 sec)*(24/1.001 frames/sec) = 133638 frames
: (2854113 ticks)+(133638 frames)*(3753.75 ticks/frame) = 504497755.5
ticks
: = 504497755 ticks
: PTS 504497755 is an I-frame in packet 76021654
:
: PTS order ..P B B I
: ___________________________/ ________drop________..
: / /
: DTS order ..I B B P B B..
: \ \ \ \
: 504486494 504490248 504494001 504497755
set CUT2=gt(pts\,504497755)
ffmpeg -copyts -i "c:\00305+00306.m2ts" -map 0 -bsf
noise=drop='%CUT1%+%CUT2%',setts=dts='%IDR%':pts=PTS -c copy -sn -dn
-muxdelay 0 "c:\Ticket_11080.m2ts"
pause
}}}
Oh, look. DVBinspector is getting the running time wrong:
"pts: 0x1E0C86B4 (504137396) => 1:33:21.5266"
should be:
504137396-2854113 = (501283283 ticks)/(90000 ticks/sec) =>
1:32:49.8142[5..]
DVBinspector isn't subtracting the initial PTS. The initial PTS has no
relevance to actual frames.
I will comment on the rest in my next comment.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11080#comment:16>
FFmpeg <https://ffmpeg.org>
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