[FFmpeg-trac] #7947(avfilter:new): Feature request: expose more frame properties as variables in drawtext filter

FFmpeg trac at avcodec.org
Mon Jun 10 20:43:18 EEST 2019


#7947: Feature request: expose more frame properties as variables in drawtext
filter
-------------------------------------+-------------------------------------
             Reporter:               |                    Owner:
  electron.rotoscope                 |
                 Type:  enhancement  |                   Status:  new
             Priority:  normal       |                Component:  avfilter
              Version:  unspecified  |               Resolution:
             Keywords:  drawtext     |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------

Comment (by electron.rotoscope):

 Replying to [comment:3 Gyan]:
 > The author should send this to the ffmpeg-devel list using git format-
 patch.
 >

 I'm trying to learn git and mailing list etiquette now well enough to be
 able to do this myself. I was hoping someone on here would be willing to
 help out.

 > {{{
 > + The metadata accessible to this function must show up using
 > + @code{ffprobe -show_packets} formatted as
 TAG:[metadata_key]=[metadata_value].
 > }}}
 >
 > Why? A user can always insert metadata inside the filtergraph using
 other filters.

 I wasn't aware of that. My main goal was to let the people after me know
 that you can't pull, say, "duration_time" since in this context while that
 is ''information about data'', it's not what ffmpeg generally means by
 ''metadata''. Would this work better?

 The use of the term metadata in ffmpeg refers to extra data, often user-
 provided or generated live during decode by other filters.
 If you're trying to read data from a stream or file, run @code{ffprobe
 -show_frames}. If it doesn't show up formatted as
 TAG:[metadata_key]=[metadata_value] then it won't be visible to this
 option.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/7947#comment:4>
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