doc/filters: drawtext additions and corrections

Document the pict_type constant. Clarify availability of metadata.
Minor grammar fixes.

Written with the help of Gyan and kepstin
This commit is contained in:
greg Luce 2019-06-20 12:08:04 -04:00 committed by Gyan Doshi
parent a1a8815220
commit 18dab6175b
1 changed files with 12 additions and 2 deletions

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@ -8962,7 +8962,10 @@ the width of the rendered text
the x and y offset coordinates where the text is drawn.
These parameters allow the @var{x} and @var{y} expressions to refer
each other, so you can for example specify @code{y=x/dar}.
to each other, so you can for example specify @code{y=x/dar}.
@item pict_type
A one character description of the current frame's picture type.
@end table
@anchor{drawtext_expansion}
@ -9032,11 +9035,18 @@ The first argument is mandatory and specifies the metadata key.
The second argument is optional and specifies a default value, used when the
metadata key is not found or empty.
Available metadata can be identified by inspecting entries
starting with TAG included within each frame section
printed by running @code{ffprobe -show_frames}.
String metadata generated in filters leading to
the drawtext filter are also available.
@item n, frame_num
The frame number, starting from 0.
@item pict_type
A 1 character description of the current picture type.
A one character description of the current picture type.
@item pts
The timestamp of the current frame.