avfilter/scale2ref: deprecate in favor of scale=rw:rh

And remove it from the documentation.

Changelog

@@ -8,6 +8,7 @@ version <next>:
 - LC3/LC3plus demuxer and muxer
 - pad_vaapi, drawbox_vaapi filters
 - vf_scale supports secondary ref input and framesync options
+- vf_scale2ref deprecated
 
 
 version 7.0:

doc/filters.texi

@@ -21590,79 +21590,6 @@ Scale a logo to 1/10th the height of a video, while preserving its display aspec
 @end example
 @end itemize
 
-@section scale2ref
-
-Scale (resize) the input video, based on a reference video.
-
-See the scale filter for available options, scale2ref supports the same but
-uses the reference video instead of the main input as basis. scale2ref also
-supports the following additional constants for the @option{w} and
-@option{h} options:
-
-@table @var
-@item main_w
-@item main_h
-The main input video's width and height
-
-@item main_a
-The same as @var{main_w} / @var{main_h}
-
-@item main_sar
-The main input video's sample aspect ratio
-
-@item main_dar, mdar
-The main input video's display aspect ratio. Calculated from
-@code{(main_w / main_h) * main_sar}.
-
-@item main_hsub
-@item main_vsub
-The main input video's horizontal and vertical chroma subsample values.
-For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub}
-is 1.
-
-@item main_n
-The (sequential) number of the main input frame, starting from 0.
-Only available with @code{eval=frame}.
-
-@item main_t
-The presentation timestamp of the main input frame, expressed as a number of
-seconds. Only available with @code{eval=frame}.
-
-@item main_pos
-The position (byte offset) of the frame in the main input stream, or NaN if
-this information is unavailable and/or meaningless (for example in case of synthetic video).
-Only available with @code{eval=frame}.
-@end table
-
-@subsection Examples
-
-@itemize
-@item
-Scale a subtitle stream (b) to match the main video (a) in size before overlaying
-@example
-'scale2ref[b][a];[a][b]overlay'
-@end example
-
-@item
-Scale a logo to 1/10th the height of a video, while preserving its display aspect ratio.
-@example
-[logo-in][video-in]scale2ref=w=oh*mdar:h=ih/10[logo-out][video-out]
-@end example
-@end itemize
-
-@subsection Commands
-
-This filter supports the following commands:
-@table @option
-@item width, w
-@item height, h
-Set the output video dimension expression.
-The command accepts the same syntax of the corresponding option.
-
-If the specified expression is not valid, it is kept at its current
-value.
-@end table
-
 @section scale2ref_npp
 
 Use the NVIDIA Performance Primitives (libnpp) to scale (resize) the input

libavfilter/vf_scale.c

@@ -368,6 +368,9 @@ static av_cold int init(AVFilterContext *ctx)
     int64_t threads;
     int ret;
 
+    if (ctx->filter == &ff_vf_scale2ref)
+        av_log(ctx, AV_LOG_WARNING, "scale2ref is deprecated, use scale=rw:rh instead\n");
+
     if (scale->size_str && (scale->w_expr || scale->h_expr)) {
         av_log(ctx, AV_LOG_ERROR,
                "Size and width/height expressions cannot be set at the same time.\n");