ffmpeg: Add display_{rotation, hflip, vflip} options

This enables overriding the rotation as well as horizontal/vertical
flip state of a specific video stream on the input side.

Additionally, switch the singular test that was utilizing the rotation
metadata to instead override the input display rotation, thus leading
to the same result.

1 files changed, 26 insertions, 0 deletions

diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
index e9020b30d5..0367930a3b 100644
--- a/doc/ffmpeg.texi
+++ b/doc/ffmpeg.texi
@@ -912,6 +912,32 @@ If used together with @option{-vcodec copy}, it will affect the aspect ratio
 stored at container level, but not the aspect ratio stored in encoded
 frames, if it exists.
 
+@item -display_rotation[:@var{stream_specifier}] @var{rotation} (@emph{input,per-stream})
+Set video rotation metadata.
+
+@var{rotation} is a decimal number specifying the amount in degree by
+which the video should be rotated counter-clockwise before being
+displayed.
+
+This option overrides the rotation/display transform metadata stored in
+the file, if any. When the video is being transcoded (rather than
+copied) and @code{-autorotate} is enabled, the video will be rotated at
+the filtering stage. Otherwise, the metadata will be written into the
+output file if the muxer supports it.
+
+If the @code{-display_hflip} and/or @code{-display_vflip} options are
+given, they are applied after the rotation specified by this option.
+
+@item -display_hflip[:@var{stream_specifier}] (@emph{input,per-stream})
+Set whether on display the image should be horizontally flipped.
+
+See the @code{-display_rotation} option for more details.
+
+@item -display_vflip[:@var{stream_specifier}] (@emph{input,per-stream})
+Set whether on display the image should be vertically flipped.
+
+See the @code{-display_rotation} option for more details.
+
 @item -vn (@emph{input/output})
 As an input option, blocks all video streams of a file from being filtered or
 being automatically selected or mapped for any output. See @code{-discard}