[FFmpeg-trac] #9775(undetermined:new): incorrect duration when start not zero

[FFmpeg]

#9775: incorrect duration when start not zero
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             Reporter:  delpeck      |                    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            |
-------------------------------------+-------------------------------------
Description changed by delpeck:

Old description:

> Hello-
> I am having a problem with the duration field when I am encoding segments
> of a HLS - ffmpeg versions greater than 4.3.3 seem to be writing an
> erroneous duration (the start + real duration).  Try the following:
>
> //ffprobe attached segment-3.ts results:
> Input #0, mpegts, from 'segment-3.ts':
>   Duration: 00:00:07.35, start: 21.512000, bitrate: 1651 kb/s
>
> //encode segment-3.ts
> ffmpeg -i segment-3.ts -copyts -map 0:v -c:v libx264 bbb-seg-enc.mp4
>
> /ffprobe the results:
> Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'bbb-seg-enc.mp4':
>   Duration: 00:00:28.87, start: 21.566016, bitrate: 345 kb/s
>

> //encode segment-3.ts without the -copyts
> ffmpeg -i segment-3.ts -copyts -map 0:v -c:v libx264 bbb-seg-enc2.mp4
>
> //ffprobe results (notice the duration is correct, but start is zero'd
> out)
> Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'bbb-seg-enc.mp4':
>   Duration: 00:00:07.30, start: 0.000000, bitrate: 1367 kb/s
>

> ffmpeg version 4.3.3 and lower write the correct duration and preserve
> the start time, is there anyway to write the correct duration and
> preserve the start time with ffmpeg 5.0.1?

New description:

 Hello-
 I am having a problem with the duration field when I am encoding segments
 of a HLS - ffmpeg versions greater than 4.3.3 seem to be writing an
 erroneous duration (the start + real duration).  Try the following:

 //ffprobe attached segment-3.ts results:
 Input #0, mpegts, from 'segment-3.ts':
   Duration: 00:00:07.35, start: 21.512000, bitrate: 1651 kb/s

 //encode segment-3.ts
 ffmpeg -i segment-3.ts -copyts -map 0:v -c:v libx264 bbb-seg-enc.mp4

 /ffprobe the results:
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'bbb-seg-enc.mp4':
   Duration: 00:00:28.87, start: 21.566016, bitrate: 345 kb/s


 //encode segment-3.ts without the -copyts
 ffmpeg -i segment-3.ts -map 0:v -c:v libx264 bbb-seg-enc2.mp4

 //ffprobe results (notice the duration is correct, but start is zero'd
 out)
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'bbb-seg-enc.mp4':
   Duration: 00:00:07.30, start: 0.000000, bitrate: 1367 kb/s


 ffmpeg version 4.3.3 and lower write the correct duration and preserve the
 start time, is there anyway to write the correct duration and preserve the
 start time with ffmpeg 5.0.1?

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Ticket URL: <https://trac.ffmpeg.org/ticket/9775#comment:3>
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