vf_drawtext: Add pkt_pos, pkt_duration, pkt_size as variables

Changes to vf_drawtext.c written by
Calvin Walton <calvin.walton@kepstin.ca>

Changes to filters.texi written by
greg Luce <electron.rotoscope@gmail.com>
with lots of help from Moritz Barsnick and Gyan

Fixes #7947.

1 files changed, 11 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index 3c406a4791..ee6a93ffbf 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -9002,6 +9002,17 @@ 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.
+
+@item pkt_pos
+The current packet's position in the input file or stream
+(in bytes, from the start of the input). A value of -1 indicates
+this info is not available.
+
+@item pkt_duration
+The current packet's duration, in seconds.
+
+@item pkt_size
+The current packet's size (in bytes).
 @end table
 
 @anchor{drawtext_expansion}