[FFmpeg-trac] #4789(undetermined:closed): v4l2 -ts abs not always working

FFmpeg trac at avcodec.org
Fri Aug 21 13:14:15 CEST 2015

#4789: v4l2 -ts abs not always working
             Reporter:  basinilya    |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:
              Version:  2.7          |  undetermined
             Keywords:  v4l2         |               Resolution:  invalid
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
Changes (by basinilya):

 * status:  new => closed
 * resolution:   => invalid


 Replying to [comment:1 cehoyos]:
 > Replying to [ticket:4789 basinilya]:
 > >   Duration: N/A, start: 83594.430406, bitrate: 165888 kb/s

 I was looking at:
 > >   pts:      0 pts_time:0

 Nevertheless, you are right: there's a difference in ffplay and ffmpeg.
 When I grab /dev/video0 with ffplay, shown PTS starts with wallclock,
 while in ffmpeg PTS starts with zero. I didn't use ffplay directly with
 real device, because it crashes the device driver. Instead I piped ffmpeg
 to ffplay and saw zero PTS, which confused me.

 Sorry for that.

 Since I do need wallclock PTS in filter expressions (but not 'time(0)',
 because it's laggy) in ffmpeg, I found a workaround:

 -vf "setpts='PTS+(RTCSTART/(TB*1000000))',do

Ticket URL: <https://trac.ffmpeg.org/ticket/4789#comment:2>
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