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FFmpeg/libavfilter/vf_perspective.c

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  1. /*

  2.  * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>

  3.  * Copyright (c) 2013 Paul B Mahol

  4.  *

  5.  * This file is part of FFmpeg.

  6.  *

  7.  * FFmpeg is free software; you can redistribute it and/or

  8.  * modify it under the terms of the GNU General Public

  9.  * License as published by the Free Software Foundation; either

  10.  * version 2 of the License, or (at your option) any later version.

  11.  *

  12.  * FFmpeg is distributed in the hope that it will be useful,

  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  15.  * GNU General Public License for more details.

  16.  *

  17.  * You should have received a copy of the GNU General Public License along

  18.  * with FFmpeg; if not, write to the Free Software

  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  20.  */

  21. 

  22. #include "libavutil/avassert.h"

  23. #include "libavutil/eval.h"

  24. #include "libavutil/imgutils.h"

  25. #include "libavutil/pixdesc.h"

  26. #include "libavutil/opt.h"

  27. #include "avfilter.h"

  28. #include "formats.h"

  29. #include "internal.h"

  30. #include "video.h"

  31. 

  32. #define SUB_PIXEL_BITS  8

  33. #define SUB_PIXELS      (1 << SUB_PIXEL_BITS)

  34. #define COEFF_BITS      11

  35. 

  36. #define LINEAR 0

  37. #define CUBIC  1

  38. 

  39. typedef struct PerspectiveContext {

  40.     const AVClass *class;

  41.     char *expr_str[4][2];

  42.     double ref[4][2];

  43.     int32_t (*pv)[2];

  44.     int32_t coeff[SUB_PIXELS][4];

  45.     int interpolation;

  46.     int linesize[4];

  47.     int height[4];

  48.     int hsub, vsub;

  49.     int nb_planes;

  50.     int sense;

  51. 

  52.     int (*perspective)(AVFilterContext *ctx,

  53.                        void *arg, int job, int nb_jobs);

  54. } PerspectiveContext;

  55. 

  56. #define OFFSET(x) offsetof(PerspectiveContext, x)

  57. #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

  58. 

  59. enum PERSPECTIVESense {

  60.     PERSPECTIVE_SENSE_SOURCE      = 0, ///< coordinates give locations in source of corners of destination.

  61.     PERSPECTIVE_SENSE_DESTINATION = 1, ///< coordinates give locations in destination of corners of source.

  62. };

  63. 

  64. static const AVOption perspective_options[] = {

  65.     { "x0", "set top left x coordinate",     OFFSET(expr_str[0][0]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },

  66.     { "y0", "set top left y coordinate",     OFFSET(expr_str[0][1]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },

  67.     { "x1", "set top right x coordinate",    OFFSET(expr_str[1][0]), AV_OPT_TYPE_STRING, {.str="W"}, 0, 0, FLAGS },

  68.     { "y1", "set top right y coordinate",    OFFSET(expr_str[1][1]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },

  69.     { "x2", "set bottom left x coordinate",  OFFSET(expr_str[2][0]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },

  70.     { "y2", "set bottom left y coordinate",  OFFSET(expr_str[2][1]), AV_OPT_TYPE_STRING, {.str="H"}, 0, 0, FLAGS },

  71.     { "x3", "set bottom right x coordinate", OFFSET(expr_str[3][0]), AV_OPT_TYPE_STRING, {.str="W"}, 0, 0, FLAGS },

  72.     { "y3", "set bottom right y coordinate", OFFSET(expr_str[3][1]), AV_OPT_TYPE_STRING, {.str="H"}, 0, 0, FLAGS },

  73.     { "interpolation", "set interpolation", OFFSET(interpolation), AV_OPT_TYPE_INT, {.i64=LINEAR}, 0, 1, FLAGS, "interpolation" },

  74.     {      "linear", "", 0, AV_OPT_TYPE_CONST, {.i64=LINEAR}, 0, 0, FLAGS, "interpolation" },

  75.     {       "cubic", "", 0, AV_OPT_TYPE_CONST, {.i64=CUBIC},  0, 0, FLAGS, "interpolation" },

  76.     { "sense",   "specify the sense of the coordinates", OFFSET(sense), AV_OPT_TYPE_INT, {.i64=PERSPECTIVE_SENSE_SOURCE}, 0, 1, FLAGS, "sense"},

  77.     {       "source", "specify locations in source to send to corners in destination",

  78.                 0, AV_OPT_TYPE_CONST, {.i64=PERSPECTIVE_SENSE_SOURCE}, 0, 0, FLAGS, "sense"},

  79.     {       "destination", "specify locations in destination to send corners of source",

  80.                 0, AV_OPT_TYPE_CONST, {.i64=PERSPECTIVE_SENSE_DESTINATION}, 0, 0, FLAGS, "sense"},

  81. 

  82.     { NULL }

  83. };

  84. 

  85. AVFILTER_DEFINE_CLASS(perspective);

  86. 

  87. static int query_formats(AVFilterContext *ctx)

  88. {

  89.     static const enum AVPixelFormat pix_fmts[] = {

  90.         AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,

  91.         AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ422P,AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ411P,

  92.         AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,

  93.         AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE

  94.     };

  95. 

  96.     AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);

  97.     if (!fmts_list)

  98.         return AVERROR(ENOMEM);

  99.     return ff_set_common_formats(ctx, fmts_list);

  100. }

  101. 

  102. static inline double get_coeff(double d)

  103. {

  104.     double coeff, A = -0.60;

  105. 

  106.     d = fabs(d);

  107. 

  108.     if (d < 1.0)

  109.         coeff = (1.0 - (A + 3.0) * d * d + (A + 2.0) * d * d * d);

  110.     else if (d < 2.0)

  111.         coeff = (-4.0 * A + 8.0 * A * d - 5.0 * A * d * d + A * d * d * d);

  112.     else

  113.         coeff = 0.0;

  114. 

  115.     return coeff;

  116. }

  117. 

  118. static const char *const var_names[] = {   "W",   "H",        NULL };

  119. enum                                   { VAR_W, VAR_H, VAR_VARS_NB };

  120. 

  121. static int config_input(AVFilterLink *inlink)

  122. {

  123.     double x0, x1, x2, x3, x4, x5, x6, x7, x8, q;

  124.     double t0, t1, t2, t3;

  125.     AVFilterContext *ctx = inlink->dst;

  126.     PerspectiveContext *s = ctx->priv;

  127.     double (*ref)[2] = s->ref;

  128.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);

  129.     double values[VAR_VARS_NB] = { [VAR_W] = inlink->w, [VAR_H] = inlink->h };

  130.     int h = inlink->h;

  131.     int w = inlink->w;

  132.     int x, y, i, j, ret;

  133. 

  134.     for (i = 0; i < 4; i++) {

  135.         for (j = 0; j < 2; j++) {

  136.             if (!s->expr_str[i][j])

  137.                 return AVERROR(EINVAL);

  138.             ret = av_expr_parse_and_eval(&s->ref[i][j], s->expr_str[i][j],

  139.                                          var_names, &values[0],

  140.                                          NULL, NULL, NULL, NULL,

  141.                                          0, 0, ctx);

  142.             if (ret < 0)

  143.                 return ret;

  144.         }

  145.     }

  146. 

  147.     s->hsub = desc->log2_chroma_w;

  148.     s->vsub = desc->log2_chroma_h;

  149.     s->nb_planes = av_pix_fmt_count_planes(inlink->format);

  150.     if ((ret = av_image_fill_linesizes(s->linesize, inlink->format, inlink->w)) < 0)

  151.         return ret;

  152. 

  153.     s->height[1] = s->height[2] = FF_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);

  154.     s->height[0] = s->height[3] = inlink->h;

  155. 

  156.     s->pv = av_realloc_f(s->pv, w * h, 2 * sizeof(*s->pv));

  157.     if (!s->pv)

  158.         return AVERROR(ENOMEM);

  159. 

  160.     switch (s->sense) {

  161.     case PERSPECTIVE_SENSE_SOURCE:

  162.         x6 = ((ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *

  163.               (ref[2][1] - ref[3][1]) -

  164.              ( ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *

  165.               (ref[2][0] - ref[3][0])) * h;

  166.         x7 = ((ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *

  167.               (ref[1][0] - ref[3][0]) -

  168.              ( ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *

  169.               (ref[1][1] - ref[3][1])) * w;

  170.         q =  ( ref[1][0] - ref[3][0]) * (ref[2][1] - ref[3][1]) -

  171.              ( ref[2][0] - ref[3][0]) * (ref[1][1] - ref[3][1]);

  172. 

  173.         x0 = q * (ref[1][0] - ref[0][0]) * h + x6 * ref[1][0];

  174.         x1 = q * (ref[2][0] - ref[0][0]) * w + x7 * ref[2][0];

  175.         x2 = q *  ref[0][0] * w * h;

  176.         x3 = q * (ref[1][1] - ref[0][1]) * h + x6 * ref[1][1];

  177.         x4 = q * (ref[2][1] - ref[0][1]) * w + x7 * ref[2][1];

  178.         x5 = q *  ref[0][1] * w * h;

  179.         x8 = q * w * h;

  180.         break;

  181.     case PERSPECTIVE_SENSE_DESTINATION:

  182.         t0 = ref[0][0] * (ref[3][1] - ref[1][1]) +

  183.              ref[1][0] * (ref[0][1] - ref[3][1]) +

  184.              ref[3][0] * (ref[1][1] - ref[0][1]);

  185.         t1 = ref[1][0] * (ref[2][1] - ref[3][1]) +

  186.              ref[2][0] * (ref[3][1] - ref[1][1]) +

  187.              ref[3][0] * (ref[1][1] - ref[2][1]);

  188.         t2 = ref[0][0] * (ref[3][1] - ref[2][1]) +

  189.              ref[2][0] * (ref[0][1] - ref[3][1]) +

  190.              ref[3][0] * (ref[2][1] - ref[0][1]);

  191.         t3 = ref[0][0] * (ref[1][1] - ref[2][1]) +

  192.              ref[1][0] * (ref[2][1] - ref[0][1]) +

  193.              ref[2][0] * (ref[0][1] - ref[1][1]);

  194. 

  195.         x0 = t0 * t1 * w * (ref[2][1] - ref[0][1]);

  196.         x1 = t0 * t1 * w * (ref[0][0] - ref[2][0]);

  197.         x2 = t0 * t1 * w * (ref[0][1] * ref[2][0] - ref[0][0] * ref[2][1]);

  198.         x3 = t1 * t2 * h * (ref[1][1] - ref[0][1]);

  199.         x4 = t1 * t2 * h * (ref[0][0] - ref[1][0]);

  200.         x5 = t1 * t2 * h * (ref[0][1] * ref[1][0] - ref[0][0] * ref[1][1]);

  201.         x6 = t1 * t2 * (ref[1][1] - ref[0][1]) +

  202.              t0 * t3 * (ref[2][1] - ref[3][1]);

  203.         x7 = t1 * t2 * (ref[0][0] - ref[1][0]) +

  204.              t0 * t3 * (ref[3][0] - ref[2][0]);

  205.         x8 = t1 * t2 * (ref[0][1] * ref[1][0] - ref[0][0] * ref[1][1]) +

  206.              t0 * t3 * (ref[2][0] * ref[3][1] - ref[2][1] * ref[3][0]);

  207.         break;

  208.     default:

  209.         av_assert0(0);

  210.     }

  211. 

  212.     for (y = 0; y < h; y++){

  213.         for (x = 0; x < w; x++){

  214.             int u, v;

  215. 

  216.             u = (int)floor(SUB_PIXELS * (x0 * x + x1 * y + x2) /

  217.                                         (x6 * x + x7 * y + x8) + 0.5);

  218.             v = (int)floor(SUB_PIXELS * (x3 * x + x4 * y + x5) /

  219.                                         (x6 * x + x7 * y + x8) + 0.5);

  220. 

  221.             s->pv[x + y * w][0] = u;

  222.             s->pv[x + y * w][1] = v;

  223.         }

  224.     }

  225. 

  226.     for (i = 0; i < SUB_PIXELS; i++){

  227.         double d = i / (double)SUB_PIXELS;

  228.         double temp[4];

  229.         double sum = 0;

  230. 

  231.         for (j = 0; j < 4; j++)

  232.             temp[j] = get_coeff(j - d - 1);

  233. 

  234.         for (j = 0; j < 4; j++)

  235.             sum += temp[j];

  236. 

  237.         for (j = 0; j < 4; j++)

  238.             s->coeff[i][j] = (int)floor((1 << COEFF_BITS) * temp[j] / sum + 0.5);

  239.     }

  240. 

  241.     return 0;

  242. }

  243. 

  244. typedef struct ThreadData {

  245.     uint8_t *dst;

  246.     int dst_linesize;

  247.     uint8_t *src;

  248.     int src_linesize;

  249.     int w, h;

  250.     int hsub, vsub;

  251. } ThreadData;

  252. 

  253. static int resample_cubic(AVFilterContext *ctx, void *arg,

  254.                           int job, int nb_jobs)

  255. {

  256.     PerspectiveContext *s = ctx->priv;

  257.     ThreadData *td = arg;

  258.     uint8_t *dst = td->dst;

  259.     int dst_linesize = td->dst_linesize;

  260.     uint8_t *src = td->src;

  261.     int src_linesize = td->src_linesize;

  262.     int w = td->w;

  263.     int h = td->h;

  264.     int hsub = td->hsub;

  265.     int vsub = td->vsub;

  266.     int start = (h * job) / nb_jobs;

  267.     int end   = (h * (job+1)) / nb_jobs;

  268.     const int linesize = s->linesize[0];

  269.     int x, y;

  270. 

  271.     for (y = start; y < end; y++) {

  272.         int sy = y << vsub;

  273.         for (x = 0; x < w; x++) {

  274.             int u, v, subU, subV, sum, sx;

  275. 

  276.             sx   = x << hsub;

  277.             u    = s->pv[sx + sy * linesize][0] >> hsub;

  278.             v    = s->pv[sx + sy * linesize][1] >> vsub;

  279.             subU = u & (SUB_PIXELS - 1);

  280.             subV = v & (SUB_PIXELS - 1);

  281.             u  >>= SUB_PIXEL_BITS;

  282.             v  >>= SUB_PIXEL_BITS;

  283. 

  284.             if (u > 0 && v > 0 && u < w - 2 && v < h - 2){

  285.                 const int index = u + v*src_linesize;

  286.                 const int a = s->coeff[subU][0];

  287.                 const int b = s->coeff[subU][1];

  288.                 const int c = s->coeff[subU][2];

  289.                 const int d = s->coeff[subU][3];

  290. 

  291.                 sum = s->coeff[subV][0] * (a * src[index - 1 -     src_linesize] + b * src[index - 0 -     src_linesize]  +

  292.                                       c *      src[index + 1 -     src_linesize] + d * src[index + 2 -     src_linesize]) +

  293.                       s->coeff[subV][1] * (a * src[index - 1                   ] + b * src[index - 0                   ]  +

  294.                                       c *      src[index + 1                   ] + d * src[index + 2                   ]) +

  295.                       s->coeff[subV][2] * (a * src[index - 1 +     src_linesize] + b * src[index - 0 +     src_linesize]  +

  296.                                       c *      src[index + 1 +     src_linesize] + d * src[index + 2 +     src_linesize]) +

  297.                       s->coeff[subV][3] * (a * src[index - 1 + 2 * src_linesize] + b * src[index - 0 + 2 * src_linesize]  +

  298.                                       c *      src[index + 1 + 2 * src_linesize] + d * src[index + 2 + 2 * src_linesize]);

  299.             } else {

  300.                 int dx, dy;

  301. 

  302.                 sum = 0;

  303. 

  304.                 for (dy = 0; dy < 4; dy++) {

  305.                     int iy = v + dy - 1;

  306. 

  307.                     if (iy < 0)

  308.                         iy = 0;

  309.                     else if (iy >= h)

  310.                         iy = h-1;

  311.                     for (dx = 0; dx < 4; dx++) {

  312.                         int ix = u + dx - 1;

  313. 

  314.                         if (ix < 0)

  315.                             ix = 0;

  316.                         else if (ix >= w)

  317.                             ix = w - 1;

  318. 

  319.                         sum += s->coeff[subU][dx] * s->coeff[subV][dy] * src[ ix + iy * src_linesize];

  320.                     }

  321.                 }

  322.             }

  323. 

  324.             sum = (sum + (1<<(COEFF_BITS * 2 - 1))) >> (COEFF_BITS * 2);

  325.             sum = av_clip_uint8(sum);

  326.             dst[x + y * dst_linesize] = sum;

  327.         }

  328.     }

  329.     return 0;

  330. }

  331. 

  332. static int resample_linear(AVFilterContext *ctx, void *arg,

  333.                            int job, int nb_jobs)

  334. {

  335.     PerspectiveContext *s = ctx->priv;

  336.     ThreadData *td = arg;

  337.     uint8_t *dst = td->dst;

  338.     int dst_linesize = td->dst_linesize;

  339.     uint8_t *src = td->src;

  340.     int src_linesize = td->src_linesize;

  341.     int w = td->w;

  342.     int h = td->h;

  343.     int hsub = td->hsub;

  344.     int vsub = td->vsub;

  345.     int start = (h * job) / nb_jobs;

  346.     int end   = (h * (job+1)) / nb_jobs;

  347.     const int linesize = s->linesize[0];

  348.     int x, y;

  349. 

  350.     for (y = start; y < end; y++){

  351.         int sy = y << vsub;

  352.         for (x = 0; x < w; x++){

  353.             int u, v, subU, subV, sum, sx, index, subUI, subVI;

  354. 

  355.             sx   = x << hsub;

  356.             u    = s->pv[sx + sy * linesize][0] >> hsub;

  357.             v    = s->pv[sx + sy * linesize][1] >> vsub;

  358.             subU = u & (SUB_PIXELS - 1);

  359.             subV = v & (SUB_PIXELS - 1);

  360.             u  >>= SUB_PIXEL_BITS;

  361.             v  >>= SUB_PIXEL_BITS;

  362. 

  363.             index = u + v * src_linesize;

  364.             subUI = SUB_PIXELS - subU;

  365.             subVI = SUB_PIXELS - subV;

  366. 

  367.             if ((unsigned)u < (unsigned)(w - 1)){

  368.                 if((unsigned)v < (unsigned)(h - 1)){

  369.                     sum = subVI * (subUI * src[index] + subU * src[index + 1]) +

  370.                           subV  * (subUI * src[index + src_linesize] + subU * src[index + src_linesize + 1]);

  371.                     sum = (sum + (1 << (SUB_PIXEL_BITS * 2 - 1)))>> (SUB_PIXEL_BITS * 2);

  372.                 } else {

  373.                     if (v < 0)

  374.                         v = 0;

  375.                     else

  376.                         v = h - 1;

  377.                     index = u + v * src_linesize;

  378.                     sum   = subUI * src[index] + subU * src[index + 1];

  379.                     sum   = (sum + (1 << (SUB_PIXEL_BITS - 1))) >> SUB_PIXEL_BITS;

  380.                 }

  381.             } else {

  382.                 if (u < 0)

  383.                     u = 0;

  384.                 else

  385.                     u = w - 1;

  386.                 if ((unsigned)v < (unsigned)(h - 1)){

  387.                     index = u + v * src_linesize;

  388.                     sum   = subVI * src[index] + subV * src[index + src_linesize];

  389.                     sum   = (sum + (1 << (SUB_PIXEL_BITS - 1))) >> SUB_PIXEL_BITS;

  390.                 } else {

  391.                     if (v < 0)

  392.                         v = 0;

  393.                     else

  394.                         v = h - 1;

  395.                     index = u + v * src_linesize;

  396.                     sum   = src[index];

  397.                 }

  398.             }

  399. 

  400.             sum = av_clip_uint8(sum);

  401.             dst[x + y * dst_linesize] = sum;

  402.         }

  403.     }

  404.     return 0;

  405. }

  406. 

  407. static av_cold int init(AVFilterContext *ctx)

  408. {

  409.     PerspectiveContext *s = ctx->priv;

  410. 

  411.     switch (s->interpolation) {

  412.     case LINEAR: s->perspective = resample_linear; break;

  413.     case CUBIC:  s->perspective = resample_cubic;  break;

  414.     }

  415. 

  416.     return 0;

  417. }

  418. 

  419. static int filter_frame(AVFilterLink *inlink, AVFrame *frame)

  420. {

  421.     AVFilterContext *ctx = inlink->dst;

  422.     AVFilterLink *outlink = ctx->outputs[0];

  423.     PerspectiveContext *s = ctx->priv;

  424.     AVFrame *out;

  425.     int plane;

  426. 

  427.     out = ff_get_video_buffer(outlink, outlink->w, outlink->h);

  428.     if (!out) {

  429.         av_frame_free(&frame);

  430.         return AVERROR(ENOMEM);

  431.     }

  432.     av_frame_copy_props(out, frame);

  433. 

  434.     for (plane = 0; plane < s->nb_planes; plane++) {

  435.         int hsub = plane == 1 || plane == 2 ? s->hsub : 0;

  436.         int vsub = plane == 1 || plane == 2 ? s->vsub : 0;

  437.         ThreadData td = {.dst = out->data[plane],

  438.                          .dst_linesize = out->linesize[plane],

  439.                          .src = frame->data[plane],

  440.                          .src_linesize = frame->linesize[plane],

  441.                          .w = s->linesize[plane],

  442.                          .h = s->height[plane],

  443.                          .hsub = hsub,

  444.                          .vsub = vsub };

  445.         ctx->internal->execute(ctx, s->perspective, &td, NULL, FFMIN(td.h, ctx->graph->nb_threads));

  446.     }

  447. 

  448.     av_frame_free(&frame);

  449.     return ff_filter_frame(outlink, out);

  450. }

  451. 

  452. static av_cold void uninit(AVFilterContext *ctx)

  453. {

  454.     PerspectiveContext *s = ctx->priv;

  455. 

  456.     av_freep(&s->pv);

  457. }

  458. 

  459. static const AVFilterPad perspective_inputs[] = {

  460.     {

  461.         .name         = "default",

  462.         .type         = AVMEDIA_TYPE_VIDEO,

  463.         .filter_frame = filter_frame,

  464.         .config_props = config_input,

  465.     },

  466.     { NULL }

  467. };

  468. 

  469. static const AVFilterPad perspective_outputs[] = {

  470.     {

  471.         .name = "default",

  472.         .type = AVMEDIA_TYPE_VIDEO,

  473.     },

  474.     { NULL }

  475. };

  476. 

  477. AVFilter ff_vf_perspective = {

  478.     .name          = "perspective",

  479.     .description   = NULL_IF_CONFIG_SMALL("Correct the perspective of video."),

  480.     .priv_size     = sizeof(PerspectiveContext),

  481.     .init          = init,

  482.     .uninit        = uninit,

  483.     .query_formats = query_formats,

  484.     .inputs        = perspective_inputs,

  485.     .outputs       = perspective_outputs,

  486.     .priv_class    = &perspective_class,

  487.     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,

  488. };