lavfi: add rotate filter

Based on the libavfilter SOC filter by Vitor Sessak, with the following additions:
* integer arithmetic
* bilinear interpolation
* RGB path
* configurable parametric angle, output width and height

Address trac issue #1500.

See thread:
Subject: [FFmpeg-devel] [WIP] rotate filter(s)
Date: 2010-10-03 17:35:49 GMT

Changelog

@@ -66,6 +66,7 @@ version <next>:
 - sab filter ported from libmpcodecs
 - ffprobe -show_chapters option
 - WavPack encoding through libwavpack
+- rotate filter
 
 
 version 1.2:

doc/filters.texi

@@ -5771,6 +5771,118 @@ much, but it will increase the amount of blurring needed to cover over
 the image and will destroy more information than necessary, and extra
 pixels will slow things down on a large logo.
 
+@section rotate
+
+Rotate video by an arbitrary angle expressed in radians.
+
+The filter accepts the following options:
+
+A description of the optional parameters follows.
+@table @option
+@item angle, a
+Set an expression for the angle by which to rotate the input video
+clockwise, expressed as a number of radians. A negative value will
+result in a counter-clockwise rotation. By default it is set to "0".
+
+This expression is evaluated for each frame.
+
+@item out_w, ow
+Set the output width expression, default value is "iw".
+This expression is evaluated just once during configuration.
+
+@item out_h, oh
+Set the output height expression, default value is "ih".
+This expression is evaluated just once during configuration.
+
+@item bilinear
+Enable bilinear interpolation if set to 1, a value of 0 disables
+it. Default value is 1.
+
+@item fillcolor, c
+Set the color used to fill the output area not covered by the rotated
+image. If the special value "none" is selected then no background is
+printed (useful for example if the background is never shown). Default
+value is "black".
+@end table
+
+The expressions for the angle and the output size can contain the
+following constants and functions:
+
+@table @option
+@item n
+sequential number of the input frame, starting from 0. It is always NAN
+before the first frame is filtered.
+
+@item t
+time in seconds of the input frame, it is set to 0 when the filter is
+configured. It is always NAN before the first frame is filtered.
+
+@item hsub
+@item vsub
+horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+
+@item in_w, iw
+@item in_h, ih
+the input video width and heigth
+
+@item out_w, ow
+@item out_h, oh
+the output width and heigth, that is the size of the padded area as
+specified by the @var{width} and @var{height} expressions
+
+@item rotw(a)
+@item roth(a)
+the minimal width/height required for completely containing the input
+video rotated by @var{a} radians.
+
+These are only available when computing the @option{out_w} and
+@option{out_h} expressions.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Rotate the input by PI/6 radians clockwise:
+@example
+rotate=PI/6
+@end example
+
+@item
+Rotate the input by PI/6 radians counter-clockwise:
+@example
+rotate=-PI/6
+@end example
+
+@item
+Apply a constant rotation with period T, starting from an angle of PI/3:
+@example
+rotate=PI/3+2*PI*t/T
+@end example
+
+@item
+Make the input video rotation oscillating with a period of T
+seconds and an amplitude of A radians:
+@example
+rotate=A*sin(2*PI/T*t)
+@end example
+
+@item
+Rotate the video, output size is choosen so that the whole rotating
+input video is always completely contained in the output:
+@example
+rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
+@end example
+
+@item
+Rotate the video, reduce the output size so that no background is ever
+shown:
+@example
+rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
+@end example
+@end itemize
+
 @section sab
 
 Apply Shape Adaptive Blur.

libavfilter/Makefile

@@ -168,6 +168,7 @@ OBJS-$(CONFIG_PERMS_FILTER)                  += f_perms.o
 OBJS-$(CONFIG_PIXDESCTEST_FILTER)            += vf_pixdesctest.o
 OBJS-$(CONFIG_PP_FILTER)                     += vf_pp.o
 OBJS-$(CONFIG_REMOVELOGO_FILTER)             += bbox.o lswsutils.o lavfutils.o vf_removelogo.o
+OBJS-$(CONFIG_ROTATE_FILTER)                 += vf_rotate.o
 OBJS-$(CONFIG_SEPARATEFIELDS_FILTER)         += vf_separatefields.o
 OBJS-$(CONFIG_SAB_FILTER)                    += vf_sab.o
 OBJS-$(CONFIG_SCALE_FILTER)                  += vf_scale.o

libavfilter/allfilters.c

@@ -163,6 +163,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(PIXDESCTEST,    pixdesctest,    vf);
     REGISTER_FILTER(PP,             pp,             vf);
     REGISTER_FILTER(REMOVELOGO,     removelogo,     vf);
+    REGISTER_FILTER(ROTATE,         rotate,         vf);
     REGISTER_FILTER(SAB,            sab,            vf);
     REGISTER_FILTER(SCALE,          scale,          vf);
     REGISTER_FILTER(SELECT,         select,         vf);

libavfilter/version.h

@@ -30,8 +30,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  3
-#define LIBAVFILTER_VERSION_MINOR  75
-#define LIBAVFILTER_VERSION_MICRO 101
+#define LIBAVFILTER_VERSION_MINOR  76
+#define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \

libavfilter/vf_rotate.c

+/*
+ * Copyright (c) 2013 Stefano Sabatini
+ * Copyright (c) 2008 Vitor Sessak
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * rotation filter, partially based on the tests/rotozoom.c program
+*/
+
+#include "libavutil/avstring.h"
+#include "libavutil/eval.h"
+#include "libavutil/opt.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/parseutils.h"
+#include "libavutil/pixdesc.h"
+
+#include "avfilter.h"
+#include "drawutils.h"
+#include "internal.h"
+#include "video.h"
+
+static const char *var_names[] = {
+    "in_w" , "iw",  ///< width of the input video
+    "in_h" , "ih",  ///< height of the input video
+    "out_w", "ow",  ///< width of the input video
+    "out_h", "oh",  ///< height of the input video
+    "hsub", "vsub",
+    "n",            ///< number of frame
+    "t",            ///< timestamp expressed in seconds
+    NULL
+};
+
+enum var_name {
+    VAR_IN_W , VAR_IW,
+    VAR_IN_H , VAR_IH,
+    VAR_OUT_W, VAR_OW,
+    VAR_OUT_H, VAR_OH,
+    VAR_HSUB, VAR_VSUB,
+    VAR_N,
+    VAR_T,
+    VAR_VARS_NB
+};
+
+typedef struct {
+    const AVClass *class;
+    double angle;
+    char *angle_expr_str;   ///< expression for the angle
+    AVExpr *angle_expr;     ///< parsed expression for the angle
+    char *outw_expr_str, *outh_expr_str;
+    int outh, outw;
+    uint8_t fillcolor[4];   ///< color expressed either in YUVA or RGBA colorspace for the padding area
+    char *fillcolor_str;
+    int fillcolor_enable;
+    int hsub, vsub;
+    int nb_planes;
+    int use_bilinear;
+    uint8_t *line[4];
+    int linestep[4];
+    float sinx, cosx;
+    double var_values[VAR_VARS_NB];
+} RotContext;
+
+#define OFFSET(x) offsetof(RotContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+
+static const AVOption rotate_options[] = {
+    { "angle",     "set angle (in radians)",       OFFSET(angle_expr_str), AV_OPT_TYPE_STRING, {.str="0"}, CHAR_MIN, CHAR_MAX, .flags=FLAGS },
+    { "a",         "set angle (in radians)",       OFFSET(angle_expr_str), AV_OPT_TYPE_STRING, {.str="0"}, CHAR_MIN, CHAR_MAX, .flags=FLAGS },
+    { "out_w",     "set output width expression",  OFFSET(outw_expr_str), AV_OPT_TYPE_STRING, {.str="iw"}, CHAR_MIN, CHAR_MAX, .flags=FLAGS },
+    { "ow",        "set output width expression",  OFFSET(outw_expr_str), AV_OPT_TYPE_STRING, {.str="iw"}, CHAR_MIN, CHAR_MAX, .flags=FLAGS },
+    { "out_h",     "set output height expression", OFFSET(outh_expr_str), AV_OPT_TYPE_STRING, {.str="ih"}, CHAR_MIN, CHAR_MAX, .flags=FLAGS },
+    { "oh",        "set output width expression",  OFFSET(outh_expr_str), AV_OPT_TYPE_STRING, {.str="ih"}, CHAR_MIN, CHAR_MAX, .flags=FLAGS },
+    { "fillcolor", "set background fill color",    OFFSET(fillcolor_str), AV_OPT_TYPE_STRING, {.str="black"}, CHAR_MIN, CHAR_MAX, .flags=FLAGS },
+    { "c",         "set background fill color",    OFFSET(fillcolor_str), AV_OPT_TYPE_STRING, {.str="black"}, CHAR_MIN, CHAR_MAX, .flags=FLAGS },
+    { "bilinear",  "use bilinear interpolation",   OFFSET(use_bilinear),  AV_OPT_TYPE_INT, {.i64=1}, 0, 1, .flags=FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(rotate);
+
+static av_cold int init(AVFilterContext *ctx)
+{
+    RotContext *rot = ctx->priv;
+
+    if (!strcmp(rot->fillcolor_str, "none"))
+        rot->fillcolor_enable = 0;
+    else if (av_parse_color(rot->fillcolor, rot->fillcolor_str, -1, ctx) >= 0)
+        rot->fillcolor_enable = 1;
+    else
+        return AVERROR(EINVAL);
+    return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    RotContext *rot = ctx->priv;
+    int i;
+
+    for (i = 0; i < 4; i++)
+        av_freep(&rot->line[i]);
+
+    av_expr_free(rot->angle_expr);
+    rot->angle_expr = NULL;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    static enum PixelFormat pix_fmts[] = {
+        AV_PIX_FMT_ARGB,   AV_PIX_FMT_RGBA,
+        AV_PIX_FMT_ABGR,   AV_PIX_FMT_BGRA,
+        AV_PIX_FMT_RGB24,  AV_PIX_FMT_BGR24,
+        AV_PIX_FMT_GRAY8,
+        AV_PIX_FMT_YUV444P,  AV_PIX_FMT_YUVJ444P,
+        AV_PIX_FMT_YUV420P,  AV_PIX_FMT_YUVJ420P,
+        AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA420P,
+        AV_PIX_FMT_NONE
+    };
+
+    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+    return 0;
+}
+
+static double get_rotated_w(void *opaque, double angle)
+{
+    RotContext *rot = opaque;
+    double inw = rot->var_values[VAR_IN_W];
+    double inh = rot->var_values[VAR_IN_H];
+    float sinx = sin(angle);
+    float cosx = cos(angle);
+
+    return FFMAX(0, inh * sinx) + FFMAX(0, -inw * cosx) +
+           FFMAX(0, inw * cosx) + FFMAX(0, -inh * sinx);
+}
+
+static double get_rotated_h(void *opaque, double angle)
+{
+    RotContext *rot = opaque;
+    double inw = rot->var_values[VAR_IN_W];
+    double inh = rot->var_values[VAR_IN_H];
+    float sinx = sin(angle);
+    float cosx = cos(angle);
+
+    return FFMAX(0, -inh * cosx) + FFMAX(0, -inw * sinx) +
+           FFMAX(0,  inh * cosx) + FFMAX(0,  inw * sinx);
+}
+
+static double (* const func1[])(void *, double) = {
+    get_rotated_w,
+    get_rotated_h,
+    NULL
+};
+
+static const char * const func1_names[] = {
+    "rotw",
+    "roth",
+    NULL
+};
+
+static int config_props(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    RotContext *rot = ctx->priv;
+    AVFilterLink *inlink = ctx->inputs[0];
+    const AVPixFmtDescriptor *pixdesc = av_pix_fmt_desc_get(inlink->format);
+    uint8_t rgba_color[4];
+    int is_packed_rgba, ret;
+    double res;
+    char *expr;
+
+    rot->hsub = pixdesc->log2_chroma_w;
+    rot->vsub = pixdesc->log2_chroma_h;
+
+    rot->var_values[VAR_IN_W] = rot->var_values[VAR_IW] = inlink->w;
+    rot->var_values[VAR_IN_H] = rot->var_values[VAR_IH] = inlink->h;
+    rot->var_values[VAR_HSUB] = 1<<rot->hsub;
+    rot->var_values[VAR_VSUB] = 1<<rot->vsub;
+    rot->var_values[VAR_N] = NAN;
+    rot->var_values[VAR_T] = NAN;
+    rot->var_values[VAR_OUT_W] = rot->var_values[VAR_OW] = NAN;
+    rot->var_values[VAR_OUT_H] = rot->var_values[VAR_OH] = NAN;
+
+    av_expr_free(rot->angle_expr);
+    rot->angle_expr = NULL;
+    if ((ret = av_expr_parse(&rot->angle_expr, expr = rot->angle_expr_str, var_names,
+                             func1_names, func1, NULL, NULL, 0, ctx)) < 0) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Error occurred parsing angle expression '%s'\n", rot->angle_expr_str);
+        return ret;
+    }
+
+#define SET_SIZE_EXPR(name, opt_name) do {                                         \
+    ret = av_expr_parse_and_eval(&res, expr = rot->name##_expr_str,                \
+                                 var_names, rot->var_values,                       \
+                                 func1_names, func1, NULL, NULL, rot, 0, ctx);     \
+    if (ret < 0 || isnan(res) || isinf(res) || res <= 0) {                         \
+        av_log(ctx, AV_LOG_ERROR,                                                  \
+               "Error parsing or evaluating expression for option %s: "            \
+               "invalid expression '%s' or non-positive or indefinite value %f\n", \
+               opt_name, expr, res);                                               \
+        return ret;                                                                \
+    }                                                                              \
+} while (0)
+
+    /* evaluate width and height */
+    av_expr_parse_and_eval(&res, expr = rot->outw_expr_str, var_names, rot->var_values,
+                           func1_names, func1, NULL, NULL, rot, 0, ctx);
+    rot->var_values[VAR_OUT_W] = rot->var_values[VAR_OW] = res;
+    rot->outw = res + 0.5;
+    SET_SIZE_EXPR(outh, "out_w");
+    rot->var_values[VAR_OUT_H] = rot->var_values[VAR_OH] = res;
+    rot->outh = res + 0.5;
+
+    /* evaluate the width again, as it may depend on the evaluated output height */
+    SET_SIZE_EXPR(outw, "out_h");
+    rot->var_values[VAR_OUT_W] = rot->var_values[VAR_OW] = res;
+    rot->outw = res + 0.5;
+
+    /* compute number of planes */
+    rot->nb_planes = av_pix_fmt_count_planes(inlink->format);
+    outlink->w = rot->outw;
+    outlink->h = rot->outh;
+
+    memcpy(rgba_color, rot->fillcolor, sizeof(rgba_color));
+    ff_fill_line_with_color(rot->line, rot->linestep, outlink->w, rot->fillcolor,
+                            outlink->format, rgba_color, &is_packed_rgba, NULL);
+    av_log(ctx, AV_LOG_INFO,
+           "w:%d h:%d -> w:%d h:%d bgcolor:0x%02X%02X%02X%02X[%s]\n",
+           inlink->w, inlink->h, outlink->w, outlink->h,
+           rot->fillcolor[0], rot->fillcolor[1], rot->fillcolor[2], rot->fillcolor[3],
+           is_packed_rgba ? "rgba" : "yuva");
+
+    return 0;
+}
+
+#define FIXP (1<<16)
+#define INT_PI 205887 //(M_PI * FIXP)
+
+/**
+ * Compute the sin of a using integer values.
+ * Input and output values are scaled by FIXP.
+ */
+static int64_t int_sin(int64_t a)
+{
+    int64_t a2, res = 0;
+    int i;
+    if (a < 0) a = INT_PI-a; // 0..inf
+    a %= 2 * INT_PI;         // 0..2PI
+
+    if (a >= INT_PI*3/2) a -= 2*INT_PI;  // -PI/2 .. 3PI/2
+    if (a >= INT_PI/2  ) a = INT_PI - a; // -PI/2 ..  PI/2
+
+    /* compute sin using Taylor series approximated to the third term */
+    a2 = (a*a)/FIXP;
+    for (i = 2; i < 7; i += 2) {
+        res += a;
+        a = -a*a2 / (FIXP*i*(i+1));
+    }
+    return res;
+}
+
+/**
+ * Interpolate the color in src at position x and y using bilinear
+ * interpolation.
+ */
+static uint8_t *interpolate_bilinear(uint8_t *dst_color,
+                                     const uint8_t *src, int src_linesize, int src_linestep,
+                                     int x, int y, int max_x, int max_y)
+{
+    int int_x = av_clip(x>>16, 0, max_x);
+    int int_y = av_clip(y>>16, 0, max_y);
+    int frac_x = x&0xFFFF;
+    int frac_y = y&0xFFFF;
+    int i;
+    int int_x1 = FFMIN(int_x+1, max_x);
+    int int_y1 = FFMIN(int_y+1, max_y);
+
+    for (i = 0; i < src_linestep; i++) {
+        int s00 = src[src_linestep * int_x  + i + src_linesize * int_y ];
+        int s01 = src[src_linestep * int_x1 + i + src_linesize * int_y ];
+        int s10 = src[src_linestep * int_x  + i + src_linesize * int_y1];
+        int s11 = src[src_linestep * int_x1 + i + src_linesize * int_y1];
+        int s0 = (((1<<16) - frac_x)*s00 + frac_x*s01);
+        int s1 = (((1<<16) - frac_x)*s10 + frac_x*s11);
+
+        dst_color[i] = ((int64_t)((1<<16) - frac_y)*s0 + (int64_t)frac_y*s1) >> 32;
+    }
+
+    return dst_color;
+}
+
+#define TS2T(ts, tb) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts)*av_q2d(tb))
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AVFilterLink *outlink = ctx->outputs[0];
+    AVFrame *out;
+    RotContext *rot = ctx->priv;
+    int angle_int, s, c, plane;
+    double res;
+
+    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+    if (!out) {
+        av_frame_free(&in);
+        return AVERROR(ENOMEM);
+    }
+    av_frame_copy_props(out, in);
+
+    rot->var_values[VAR_N] = inlink->frame_count;
+    rot->var_values[VAR_T] = TS2T(in->pts, inlink->time_base);
+    rot->angle = res = av_expr_eval(rot->angle_expr, rot->var_values, rot);
+
+    av_log(ctx, AV_LOG_DEBUG, "n:%f time:%f angle:%f/PI\n",
+           rot->var_values[VAR_N], rot->var_values[VAR_T], rot->angle/M_PI);
+
+    angle_int = res * FIXP;
+    s = int_sin(angle_int);
+    c = int_sin(angle_int + INT_PI/2);
+
+    /* fill background */
+    if (rot->fillcolor_enable)
+        ff_draw_rectangle(out->data, out->linesize,
+                          rot->line, rot->linestep, rot->hsub, rot->vsub,
+                          0, 0, outlink->w, outlink->h);
+
+    for (plane = 0; plane < rot->nb_planes; plane++) {
+        int hsub = plane == 1 || plane == 2 ? rot->hsub : 0;
+        int vsub = plane == 1 || plane == 2 ? rot->vsub : 0;
+        int inw  = FF_CEIL_RSHIFT(inlink->w, hsub);
+        int inh  = FF_CEIL_RSHIFT(inlink->h, vsub);
+        int outw = FF_CEIL_RSHIFT(outlink->w, hsub);
+        int outh = FF_CEIL_RSHIFT(outlink->h, hsub);
+
+        const int xi = -outw/2 * c;
+        const int yi =  outw/2 * s;
+        int xprime = -outh/2 * s;
+        int yprime = -outh/2 * c;
+        int i, j, x, y;
+
+        for (j = 0; j < outh; j++) {
+            x = xprime + xi + FIXP*inw/2;
+            y = yprime + yi + FIXP*inh/2;
+
+            for (i = 0; i < outw; i++) {
+                int32_t v;
+                int x1, y1;
+                uint8_t *pin, *pout;
+                x += c;
+                y -= s;
+                x1 = x>>16;
+                y1 = y>>16;
+
+                /* the out-of-range values avoid border artifacts */
+                if (x1 >= -1 && x1 <= inw && y1 >= -1 && y1 <= inh) {
+                    uint8_t inp_inv[4]; /* interpolated input value */
+                    pout = out->data[plane] + j * out->linesize[plane] + i * rot->linestep[plane];
+                    if (rot->use_bilinear) {
+                        pin = interpolate_bilinear(inp_inv,
+                                                   in->data[plane], in->linesize[plane], rot->linestep[plane],
+                                                   x, y, inw-1, inh-1);
+                    } else {
+                        int x2 = av_clip(x1, 0, inw-1);
+                        int y2 = av_clip(y1, 0, inh-1);
+                        pin = in->data[plane] + y2 * in->linesize[plane] + x2 * rot->linestep[plane];
+                    }
+                    switch (rot->linestep[plane]) {
+                    case 1:
+                        *pout = *pin;
+                        break;
+                    case 2:
+                        *((uint16_t *)pout) = *((uint16_t *)pin);
+                        break;
+                    case 3:
+                        v = AV_RB24(pin);
+                        AV_WB24(pout, v);
+                        break;
+                    case 4:
+                        *((uint32_t *)pout) = *((uint32_t *)pin);
+                        break;
+                    default:
+                        memcpy(pout, pin, rot->linestep[plane]);
+                        break;
+                    }
+                }
+            }
+            xprime += s;
+            yprime += c;
+        }
+    }
+
+    av_frame_free(&in);
+    return ff_filter_frame(outlink, out);
+}
+
+static const AVFilterPad rotate_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad rotate_outputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_props,
+    },
+    { NULL }
+};
+
+AVFilter avfilter_vf_rotate = {
+    .name          = "rotate",
+    .description   = NULL_IF_CONFIG_SMALL("Rotate the input image."),
+    .priv_size     = sizeof(RotContext),
+    .init          = init,
+    .uninit        = uninit,
+    .query_formats = query_formats,
+    .inputs        = rotate_inputs,
+    .outputs       = rotate_outputs,
+    .priv_class    = &rotate_class,
+    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
+};