Re: [FFmpeg-devel] [PATCH v6 1/2] ffmpeg: Add display_{rotation, hflip, vflip} options

[Anton Khirnov <anton@khirnov.net>]

Quoting Thilo Borgmann (2022-09-26 07:57:52)
> From: Jan Ekström <jeebjp@gmail.com>
> 
> 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.
> ---
>  doc/ffmpeg.texi             | 29 +++++++++++++++++++++
>  fftools/ffmpeg.h            |  6 +++++
>  fftools/ffmpeg_opt.c        | 50 +++++++++++++++++++++++++++++++++++++
>  tests/fate/filter-video.mak |  2 +-
>  4 files changed, 86 insertions(+), 1 deletion(-)
> 
> diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
> index 42440d93b4..6016b43892 100644
> --- a/doc/ffmpeg.texi
> +++ b/doc/ffmpeg.texi
> @@ -912,6 +912,35 @@ 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 the video display rotation in degrees specified by @var{rotation}.
> +
> +@var{rotation} is a floating point number that describes a pure
> +counter-clockwise rotation in degrees.
> +When setting this, @code{-autorotate} logic will be affected.
> +For additional parameters affecting display matrix side data into which this
> +information is saved, see @code{-display_hflip}, @code{-display_vflip}.
> +
> +These options work as a unit, so if only one of them is set, then the display
> +matrix will be overridden to that specific value with the rest being set to
> +default values.
> +
> +If unset, the default value if a display matrix is being defined is a rotation
> +of zero degrees.
> +
> +@item -display_hflip[:@var{stream_specifier}] (@emph{input,per-stream})
> +Set whether on display the image should be horizontally flipped.
> +
> +If unset, the default value if a display matrix is being defined is that there
> +is no additional horizontal flip. See @code{-display_rotation}.
> +
> +@item -display_vflip[:@var{stream_specifier}] (@emph{input,per-stream})
> +Set whether on display the image should be vertically flipped.
> +
> +If unset, the default value if a display matrix is being defined is that there
> +is no additional vertical flip. See @code{-display_rotation}.

@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.

> +static void add_display_matrix_to_stream(OptionsContext *o,
> +                                         AVFormatContext *ctx, AVStream *st)
> +{
> +    double rotation = DBL_MAX;
> +    int hflip = -1, vflip = -1;
> +    int hflip_set = 0, vflip_set = 0, rotation_set = 0;
> +    uint8_t *buf = NULL;

should be int32_t*

Otherwise seems ok.

-- 
Anton Khirnov
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