/*
  * 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"
 

 #include <float.h>
 

 static const char * const 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 RotContext {

     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;
     float sinx, cosx;
     double var_values[VAR_VARS_NB];

     FFDrawContext draw;
     FFDrawColor color;

     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);

 } RotContext;
 

 typedef struct ThreadData {
     AVFrame *in, *out;
     int inw,  inh;
     int outw, outh;
     int plane;
     int xi, yi;
     int xprime, yprime;
     int c, s;
 } ThreadData;
 

 #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 height 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_BOOL, {.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;
 
     av_expr_free(rot->angle_expr);
     rot->angle_expr = NULL;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {

     static const enum AVPixelFormat pix_fmts[] = {

         AV_PIX_FMT_GBRP,   AV_PIX_FMT_GBRAP,

         AV_PIX_FMT_ARGB,   AV_PIX_FMT_RGBA,
         AV_PIX_FMT_ABGR,   AV_PIX_FMT_BGRA,

         AV_PIX_FMT_0RGB,   AV_PIX_FMT_RGB0,
         AV_PIX_FMT_0BGR,   AV_PIX_FMT_BGR0,

         AV_PIX_FMT_RGB24,  AV_PIX_FMT_BGR24,
         AV_PIX_FMT_GRAY8,

         AV_PIX_FMT_YUV410P,

         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_YUV420P10LE, AV_PIX_FMT_YUVA420P10LE,
         AV_PIX_FMT_YUV444P10LE, AV_PIX_FMT_YUVA444P10LE,
         AV_PIX_FMT_YUV420P12LE,
         AV_PIX_FMT_YUV444P12LE,
         AV_PIX_FMT_YUV444P16LE, AV_PIX_FMT_YUVA444P16LE,
         AV_PIX_FMT_YUV420P16LE, AV_PIX_FMT_YUVA420P16LE,
         AV_PIX_FMT_YUV444P9LE, AV_PIX_FMT_YUVA444P9LE,
         AV_PIX_FMT_YUV420P9LE, AV_PIX_FMT_YUVA420P9LE,

         AV_PIX_FMT_NONE
     };
 

     AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
     if (!fmts_list)
         return AVERROR(ENOMEM);
     return ff_set_common_formats(ctx, fmts_list);

 }
 
 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
 };
 

 #define FIXP (1<<16)
 #define FIXP2 (1<<20)
 #define INT_PI 3294199 //(M_PI * FIXP2)
 
 /**
  * Compute the sin of a using integer values.
  * Input is scaled by FIXP2 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 fifth term */
     a2 = (a*a)/(FIXP2);
     for (i = 2; i < 11; i += 2) {
         res += a;
         a = -a*a2 / (FIXP2*i*(i+1));
     }
     return (res + 8)>>4;
 }
 
 /**
  * Interpolate the color in src at position x and y using bilinear
  * interpolation.
  */
 static uint8_t *interpolate_bilinear8(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;
 }
 
 /**
  * Interpolate the color in src at position x and y using bilinear
  * interpolation.
  */
 static uint8_t *interpolate_bilinear16(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+=2) {
         int s00 = AV_RL16(&src[src_linestep * int_x  + i + src_linesize * int_y ]);
         int s01 = AV_RL16(&src[src_linestep * int_x1 + i + src_linesize * int_y ]);
         int s10 = AV_RL16(&src[src_linestep * int_x  + i + src_linesize * int_y1]);
         int s11 = AV_RL16(&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);
 
         AV_WL16(&dst_color[i], ((int64_t)((1<<16) - frac_y)*s0 + (int64_t)frac_y*s1) >> 32);
     }
 
     return dst_color;
 }
 

 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);

     int ret;

     double res;
     char *expr;
 

     ff_draw_init(&rot->draw, inlink->format, 0);
     ff_draw_color(&rot->draw, &rot->color, rot->fillcolor);
 

     rot->hsub = pixdesc->log2_chroma_w;
     rot->vsub = pixdesc->log2_chroma_h;
 

     if (pixdesc->comp[0].depth == 8)
         rot->interpolate_bilinear = interpolate_bilinear8;
     else
         rot->interpolate_bilinear = interpolate_bilinear16;
 

     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_h");

     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_w");

     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;
     return 0;
 }
 

 static av_always_inline void copy_elem(uint8_t *pout, const uint8_t *pin, int elem_size)
 {
     int v;
     switch (elem_size) {
     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, elem_size);
         break;
     }
 }
 
 static av_always_inline void simple_rotate_internal(uint8_t *dst, const uint8_t *src, int src_linesize, int angle, int elem_size, int len)
 {
     int i;
     switch(angle) {
     case 0:
         memcpy(dst, src, elem_size * len);
         break;
     case 1:
         for (i = 0; i<len; i++)
             copy_elem(dst + i*elem_size, src + (len-i-1)*src_linesize, elem_size);
         break;
     case 2:
         for (i = 0; i<len; i++)
             copy_elem(dst + i*elem_size, src + (len-i-1)*elem_size, elem_size);
         break;
     case 3:
         for (i = 0; i<len; i++)
             copy_elem(dst + i*elem_size, src + i*src_linesize, elem_size);
         break;
     }
 }
 
 static av_always_inline void simple_rotate(uint8_t *dst, const uint8_t *src, int src_linesize, int angle, int elem_size, int len)
 {
     switch(elem_size) {
     case 1 : simple_rotate_internal(dst, src, src_linesize, angle, 1, len); break;
     case 2 : simple_rotate_internal(dst, src, src_linesize, angle, 2, len); break;
     case 3 : simple_rotate_internal(dst, src, src_linesize, angle, 3, len); break;
     case 4 : simple_rotate_internal(dst, src, src_linesize, angle, 4, len); break;
     default: simple_rotate_internal(dst, src, src_linesize, angle, elem_size, len); break;
     }
 }
 

 #define TS2T(ts, tb) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts)*av_q2d(tb))
 

 static int filter_slice(AVFilterContext *ctx, void *arg, int job, int nb_jobs)
 {
     ThreadData *td = arg;
     AVFrame *in = td->in;
     AVFrame *out = td->out;
     RotContext *rot = ctx->priv;
     const int outw = td->outw, outh = td->outh;
     const int inw = td->inw, inh = td->inh;
     const int plane = td->plane;
     const int xi = td->xi, yi = td->yi;
     const int c = td->c, s = td->s;
     const int start = (outh *  job   ) / nb_jobs;
     const int end   = (outh * (job+1)) / nb_jobs;
     int xprime = td->xprime + start * s;
     int yprime = td->yprime + start * c;
     int i, j, x, y;
 
     for (j = start; j < end; j++) {

         x = xprime + xi + FIXP*(inw-1)/2;
         y = yprime + yi + FIXP*(inh-1)/2;

         if (fabs(rot->angle - 0) < FLT_EPSILON && outw == inw && outh == inh) {
             simple_rotate(out->data[plane] + j * out->linesize[plane],
                            in->data[plane] + j *  in->linesize[plane],
                           in->linesize[plane], 0, rot->draw.pixelstep[plane], outw);
         } else if (fabs(rot->angle - M_PI/2) < FLT_EPSILON && outw == inh && outh == inw) {
             simple_rotate(out->data[plane] + j * out->linesize[plane],
                            in->data[plane] + j * rot->draw.pixelstep[plane],
                           in->linesize[plane], 1, rot->draw.pixelstep[plane], outw);
         } else if (fabs(rot->angle - M_PI) < FLT_EPSILON && outw == inw && outh == inh) {
             simple_rotate(out->data[plane] + j * out->linesize[plane],
                            in->data[plane] + (outh-j-1) *  in->linesize[plane],
                           in->linesize[plane], 2, rot->draw.pixelstep[plane], outw);
         } else if (fabs(rot->angle - 3*M_PI/2) < FLT_EPSILON && outw == inh && outh == inw) {
             simple_rotate(out->data[plane] + j * out->linesize[plane],
                            in->data[plane] + (outh-j-1) * rot->draw.pixelstep[plane],
                           in->linesize[plane], 3, rot->draw.pixelstep[plane], outw);
         } else {
 

         for (i = 0; i < outw; i++) {
             int32_t v;
             int x1, y1;
             uint8_t *pin, *pout;
             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->draw.pixelstep[plane];
                 if (rot->use_bilinear) {

                     pin = rot->interpolate_bilinear(inp_inv,
                                                     in->data[plane], in->linesize[plane], rot->draw.pixelstep[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->draw.pixelstep[plane];
                 }
                 switch (rot->draw.pixelstep[plane]) {
                 case 1:
                     *pout = *pin;
                     break;
                 case 2:

                     v = AV_RL16(pin);
                     AV_WL16(pout, v);

                     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->draw.pixelstep[plane]);
                     break;
                 }
             }

             x += c;
             y -= s;

         }

         }

         xprime += s;
         yprime += c;
     }
 
     return 0;
 }
 

 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_out;

     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 * 16;

     s = int_sin(angle_int);
     c = int_sin(angle_int + INT_PI/2);
 
     /* fill background */
     if (rot->fillcolor_enable)

         ff_fill_rectangle(&rot->draw, &rot->color, out->data, out->linesize,

                           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;

         const int outw = AV_CEIL_RSHIFT(outlink->w, hsub);
         const int outh = AV_CEIL_RSHIFT(outlink->h, vsub);

         ThreadData td = { .in = in,   .out  = out,

                           .inw  = AV_CEIL_RSHIFT(inlink->w, hsub),
                           .inh  = AV_CEIL_RSHIFT(inlink->h, vsub),

                           .outh = outh, .outw = outw,

                           .xi = -(outw-1) * c / 2, .yi =  (outw-1) * s / 2,
                           .xprime = -(outh-1) * s / 2,
                           .yprime = -(outh-1) * c / 2,

                           .plane = plane, .c = c, .s = s };
 
 

         ctx->internal->execute(ctx, filter_slice, &td, NULL, FFMIN(outh, ff_filter_get_nb_threads(ctx)));

     }
 
     av_frame_free(&in);
     return ff_filter_frame(outlink, out);
 }
 

 static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
                            char *res, int res_len, int flags)
 {
     RotContext *rot = ctx->priv;
     int ret;
 
     if (!strcmp(cmd, "angle") || !strcmp(cmd, "a")) {
         AVExpr *old = rot->angle_expr;
         ret = av_expr_parse(&rot->angle_expr, args, var_names,
                             NULL, NULL, NULL, NULL, 0, ctx);
         if (ret < 0) {
             av_log(ctx, AV_LOG_ERROR,
                    "Error when parsing the expression '%s' for angle command\n", args);
             rot->angle_expr = old;
             return ret;
         }
         av_expr_free(old);
     } else
         ret = AVERROR(ENOSYS);
 
     return ret;
 }
 

 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 ff_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,

     .process_command = process_command,

     .inputs        = rotate_inputs,
     .outputs       = rotate_outputs,
     .priv_class    = &rotate_class,

     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,

 };