vf_tinterlace.c 25.1 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564
/*
 * Copyright (c) 2017 Thomas Mundt <tmundt75@gmail.com>
 * Copyright (c) 2011 Stefano Sabatini
 * Copyright (c) 2010 Baptiste Coudurier
 * Copyright (c) 2003 Michael Zucchi <notzed@ximian.com>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 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 General Public License for more details.
 *
 * You should have received a copy of the GNU 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
 * temporal field interlace filter, ported from MPlayer/libmpcodecs
 */

#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
#include "libavutil/avassert.h"
#include "avfilter.h"
#include "internal.h"
#include "tinterlace.h"

#define OFFSET(x) offsetof(TInterlaceContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

static const AVOption tinterlace_options[] = {
    {"mode",              "select interlace mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=MODE_MERGE}, 0, MODE_NB-1, FLAGS, "mode"},
    {"merge",             "merge fields",                                 0, AV_OPT_TYPE_CONST, {.i64=MODE_MERGE},             INT_MIN, INT_MAX, FLAGS, "mode"},
    {"drop_even",         "drop even fields",                             0, AV_OPT_TYPE_CONST, {.i64=MODE_DROP_EVEN},         INT_MIN, INT_MAX, FLAGS, "mode"},
    {"drop_odd",          "drop odd fields",                              0, AV_OPT_TYPE_CONST, {.i64=MODE_DROP_ODD},          INT_MIN, INT_MAX, FLAGS, "mode"},
    {"pad",               "pad alternate lines with black",               0, AV_OPT_TYPE_CONST, {.i64=MODE_PAD},               INT_MIN, INT_MAX, FLAGS, "mode"},
    {"interleave_top",    "interleave top and bottom fields",             0, AV_OPT_TYPE_CONST, {.i64=MODE_INTERLEAVE_TOP},    INT_MIN, INT_MAX, FLAGS, "mode"},
    {"interleave_bottom", "interleave bottom and top fields",             0, AV_OPT_TYPE_CONST, {.i64=MODE_INTERLEAVE_BOTTOM}, INT_MIN, INT_MAX, FLAGS, "mode"},
    {"interlacex2",       "interlace fields from two consecutive frames", 0, AV_OPT_TYPE_CONST, {.i64=MODE_INTERLACEX2},       INT_MIN, INT_MAX, FLAGS, "mode"},
    {"mergex2",           "merge fields keeping same frame rate",         0, AV_OPT_TYPE_CONST, {.i64=MODE_MERGEX2},           INT_MIN, INT_MAX, FLAGS, "mode"},

    {"flags",             "set flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = 0}, 0, INT_MAX, 0, "flags" },
    {"low_pass_filter",   "enable vertical low-pass filter",              0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_VLPF}, INT_MIN, INT_MAX, FLAGS, "flags" },
    {"vlpf",              "enable vertical low-pass filter",              0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_VLPF}, INT_MIN, INT_MAX, FLAGS, "flags" },
    {"complex_filter",    "enable complex vertical low-pass filter",      0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_CVLPF},INT_MIN, INT_MAX, FLAGS, "flags" },
    {"cvlpf",             "enable complex vertical low-pass filter",      0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_CVLPF},INT_MIN, INT_MAX, FLAGS, "flags" },
    {"exact_tb",          "force a timebase which can represent timestamps exactly", 0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_EXACT_TB}, INT_MIN, INT_MAX, FLAGS, "flags" },

    {NULL}
};

AVFILTER_DEFINE_CLASS(tinterlace);

static const AVOption interlace_options[] = {
   { "scan",              "scanning mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64 = MODE_TFF}, 0, 1, FLAGS, "mode"},
   { "tff",               "top field first",                              0, AV_OPT_TYPE_CONST, {.i64 = MODE_TFF}, INT_MIN, INT_MAX, FLAGS, .unit = "mode"},
   { "bff",               "bottom field first",                           0, AV_OPT_TYPE_CONST, {.i64 = MODE_BFF}, INT_MIN, INT_MAX, FLAGS, .unit = "mode"},
   { "lowpass",           "set vertical low-pass filter", OFFSET(flags), AV_OPT_TYPE_FLAGS,   {.i64 = TINTERLACE_FLAG_VLPF}, 0, 2, FLAGS, "flags" },
   { "off",               "disable vertical low-pass filter",             0, AV_OPT_TYPE_CONST, {.i64 = 0}, INT_MIN, INT_MAX, FLAGS, "flags" },
   { "linear",            "linear vertical low-pass filter",              0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_VLPF}, INT_MIN, INT_MAX, FLAGS, "flags" },
   { "complex",           "complex vertical low-pass filter",             0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_CVLPF},INT_MIN, INT_MAX, FLAGS, "flags" },

   { NULL }
};

AVFILTER_DEFINE_CLASS(interlace);

#define FULL_SCALE_YUVJ_FORMATS \
    AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P

static const enum AVPixelFormat full_scale_yuvj_pix_fmts[] = {
    FULL_SCALE_YUVJ_FORMATS, AV_PIX_FMT_NONE
};

static const AVRational standard_tbs[] = {
    {1, 25},
    {1, 30},
    {1001, 30000},
};

static int query_formats(AVFilterContext *ctx)
{
    static const enum AVPixelFormat pix_fmts[] = {
        AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
        AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
        AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
        AV_PIX_FMT_YUV420P10LE, AV_PIX_FMT_YUV422P10LE,
        AV_PIX_FMT_YUV440P10LE, AV_PIX_FMT_YUV444P10LE,
        AV_PIX_FMT_YUV420P12LE, AV_PIX_FMT_YUV422P12LE,
        AV_PIX_FMT_YUV440P12LE, AV_PIX_FMT_YUV444P12LE,
        AV_PIX_FMT_YUVA420P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA444P,
        AV_PIX_FMT_YUVA420P10LE, AV_PIX_FMT_YUVA422P10LE, AV_PIX_FMT_YUVA444P10LE,
        AV_PIX_FMT_GRAY8, FULL_SCALE_YUVJ_FORMATS,
        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 void lowpass_line_c(uint8_t *dstp, ptrdiff_t width, const uint8_t *srcp,
                           ptrdiff_t mref, ptrdiff_t pref, int clip_max)
{
    const uint8_t *srcp_above = srcp + mref;
    const uint8_t *srcp_below = srcp + pref;
    int i;
    for (i = 0; i < width; i++) {
        // this calculation is an integer representation of
        // '0.5 * current + 0.25 * above + 0.25 * below'
        // '1 +' is for rounding.
        dstp[i] = (1 + srcp[i] + srcp[i] + srcp_above[i] + srcp_below[i]) >> 2;
    }
}

static void lowpass_line_c_16(uint8_t *dst8, ptrdiff_t width, const uint8_t *src8,
                              ptrdiff_t mref, ptrdiff_t pref, int clip_max)
{
    uint16_t *dstp = (uint16_t *)dst8;
    const uint16_t *srcp = (const uint16_t *)src8;
    const uint16_t *srcp_above = srcp + mref / 2;
    const uint16_t *srcp_below = srcp + pref / 2;
    int i, src_x;
    for (i = 0; i < width; i++) {
        // this calculation is an integer representation of
        // '0.5 * current + 0.25 * above + 0.25 * below'
        // '1 +' is for rounding.
        src_x   = av_le2ne16(srcp[i]) << 1;
        dstp[i] = av_le2ne16((1 + src_x + av_le2ne16(srcp_above[i])
                             + av_le2ne16(srcp_below[i])) >> 2);
    }
}

static void lowpass_line_complex_c(uint8_t *dstp, ptrdiff_t width, const uint8_t *srcp,
                                   ptrdiff_t mref, ptrdiff_t pref, int clip_max)
{
    const uint8_t *srcp_above = srcp + mref;
    const uint8_t *srcp_below = srcp + pref;
    const uint8_t *srcp_above2 = srcp + mref * 2;
    const uint8_t *srcp_below2 = srcp + pref * 2;
    int i, src_x, src_ab;
    for (i = 0; i < width; i++) {
        // this calculation is an integer representation of
        // '0.75 * current + 0.25 * above + 0.25 * below - 0.125 * above2 - 0.125 * below2'
        // '4 +' is for rounding.
        src_x   = srcp[i] << 1;
        src_ab  = srcp_above[i] + srcp_below[i];
        dstp[i] = av_clip_uint8((4 + ((srcp[i] + src_x + src_ab) << 1)
                                - srcp_above2[i] - srcp_below2[i]) >> 3);
        // Prevent over-sharpening:
        // dst must not exceed src when the average of above and below
        // is less than src. And the other way around.
        if (src_ab > src_x) {
            if (dstp[i] < srcp[i])
                dstp[i] = srcp[i];
        } else if (dstp[i] > srcp[i])
            dstp[i] = srcp[i];
    }
}

static void lowpass_line_complex_c_16(uint8_t *dst8, ptrdiff_t width, const uint8_t *src8,
                                      ptrdiff_t mref, ptrdiff_t pref, int clip_max)
{
    uint16_t *dstp = (uint16_t *)dst8;
    const uint16_t *srcp = (const uint16_t *)src8;
    const uint16_t *srcp_above = srcp + mref / 2;
    const uint16_t *srcp_below = srcp + pref / 2;
    const uint16_t *srcp_above2 = srcp + mref;
    const uint16_t *srcp_below2 = srcp + pref;
    int i, dst_le, src_le, src_x, src_ab;
    for (i = 0; i < width; i++) {
        // this calculation is an integer representation of
        // '0.75 * current + 0.25 * above + 0.25 * below - 0.125 * above2 - 0.125 * below2'
        // '4 +' is for rounding.
        src_le = av_le2ne16(srcp[i]);
        src_x  = src_le << 1;
        src_ab = av_le2ne16(srcp_above[i]) + av_le2ne16(srcp_below[i]);
        dst_le = av_clip((4 + ((src_le + src_x + src_ab) << 1)
                         - av_le2ne16(srcp_above2[i])
                         - av_le2ne16(srcp_below2[i])) >> 3, 0, clip_max);
        // Prevent over-sharpening:
        // dst must not exceed src when the average of above and below
        // is less than src. And the other way around.
        if (src_ab > src_x) {
            if (dst_le < src_le)
                dstp[i] = av_le2ne16(src_le);
            else
                dstp[i] = av_le2ne16(dst_le);
        } else if (dst_le > src_le) {
            dstp[i] = av_le2ne16(src_le);
        } else
            dstp[i] = av_le2ne16(dst_le);
    }
}

static av_cold void uninit(AVFilterContext *ctx)
{
    TInterlaceContext *tinterlace = ctx->priv;

    av_frame_free(&tinterlace->cur );
    av_frame_free(&tinterlace->next);
    av_freep(&tinterlace->black_data[0]);
}

static int config_out_props(AVFilterLink *outlink)
{
    AVFilterContext *ctx = outlink->src;
    AVFilterLink *inlink = outlink->src->inputs[0];
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(outlink->format);
    TInterlaceContext *tinterlace = ctx->priv;
    int i;

    tinterlace->vsub = desc->log2_chroma_h;
    outlink->w = inlink->w;
    outlink->h = tinterlace->mode == MODE_MERGE || tinterlace->mode == MODE_PAD || tinterlace->mode == MODE_MERGEX2?
        inlink->h*2 : inlink->h;
    if (tinterlace->mode == MODE_MERGE || tinterlace->mode == MODE_PAD || tinterlace->mode == MODE_MERGEX2)
        outlink->sample_aspect_ratio = av_mul_q(inlink->sample_aspect_ratio,
                                                av_make_q(2, 1));

    if (tinterlace->mode == MODE_PAD) {
        uint8_t black[4] = { 0, 0, 0, 16 };
        int ret;
        ff_draw_init(&tinterlace->draw, outlink->format, 0);
        ff_draw_color(&tinterlace->draw, &tinterlace->color, black);
        if (ff_fmt_is_in(outlink->format, full_scale_yuvj_pix_fmts))
            tinterlace->color.comp[0].u8[0] = 0;
        ret = av_image_alloc(tinterlace->black_data, tinterlace->black_linesize,
                             outlink->w, outlink->h, outlink->format, 16);
        if (ret < 0)
            return ret;

        ff_fill_rectangle(&tinterlace->draw, &tinterlace->color, tinterlace->black_data,
                          tinterlace->black_linesize, 0, 0, outlink->w, outlink->h);
    }
    if (tinterlace->flags & (TINTERLACE_FLAG_VLPF | TINTERLACE_FLAG_CVLPF)
            && !(tinterlace->mode == MODE_INTERLEAVE_TOP
              || tinterlace->mode == MODE_INTERLEAVE_BOTTOM)) {
        av_log(ctx, AV_LOG_WARNING, "low_pass_filter flags ignored with mode %d\n",
                tinterlace->mode);
        tinterlace->flags &= ~(TINTERLACE_FLAG_VLPF | TINTERLACE_FLAG_CVLPF);
    }
    tinterlace->preout_time_base = inlink->time_base;
    if (tinterlace->mode == MODE_INTERLACEX2) {
        tinterlace->preout_time_base.den *= 2;
        outlink->frame_rate = av_mul_q(inlink->frame_rate, (AVRational){2,1});
        outlink->time_base  = av_mul_q(inlink->time_base , (AVRational){1,2});
    } else if (tinterlace->mode == MODE_MERGEX2) {
        outlink->frame_rate = inlink->frame_rate;
        outlink->time_base  = inlink->time_base;
    } else if (tinterlace->mode != MODE_PAD) {
        outlink->frame_rate = av_mul_q(inlink->frame_rate, (AVRational){1,2});
        outlink->time_base  = av_mul_q(inlink->time_base , (AVRational){2,1});
    }

    for (i = 0; i<FF_ARRAY_ELEMS(standard_tbs); i++){
        if (!av_cmp_q(standard_tbs[i], outlink->time_base))
            break;
    }
    if (i == FF_ARRAY_ELEMS(standard_tbs) ||
        (tinterlace->flags & TINTERLACE_FLAG_EXACT_TB))
        outlink->time_base = tinterlace->preout_time_base;

    tinterlace->csp = av_pix_fmt_desc_get(outlink->format);
    if (tinterlace->flags & TINTERLACE_FLAG_CVLPF) {
        if (tinterlace->csp->comp[0].depth > 8)
            tinterlace->lowpass_line = lowpass_line_complex_c_16;
        else
            tinterlace->lowpass_line = lowpass_line_complex_c;
        if (ARCH_X86)
            ff_tinterlace_init_x86(tinterlace);
    } else if (tinterlace->flags & TINTERLACE_FLAG_VLPF) {
        if (tinterlace->csp->comp[0].depth > 8)
            tinterlace->lowpass_line = lowpass_line_c_16;
        else
            tinterlace->lowpass_line = lowpass_line_c;
        if (ARCH_X86)
            ff_tinterlace_init_x86(tinterlace);
    }

    av_log(ctx, AV_LOG_VERBOSE, "mode:%d filter:%s h:%d -> h:%d\n", tinterlace->mode,
           (tinterlace->flags & TINTERLACE_FLAG_CVLPF) ? "complex" :
           (tinterlace->flags & TINTERLACE_FLAG_VLPF) ? "linear" : "off",
           inlink->h, outlink->h);

    return 0;
}

#define FIELD_UPPER           0
#define FIELD_LOWER           1
#define FIELD_UPPER_AND_LOWER 2

/**
 * Copy picture field from src to dst.
 *
 * @param src_field copy from upper, lower field or both
 * @param interleave leave a padding line between each copied line
 * @param dst_field copy to upper or lower field,
 *        only meaningful when interleave is selected
 * @param flags context flags
 */
static inline
void copy_picture_field(TInterlaceContext *tinterlace,
                        uint8_t *dst[4], int dst_linesize[4],
                        const uint8_t *src[4], int src_linesize[4],
                        enum AVPixelFormat format, int w, int src_h,
                        int src_field, int interleave, int dst_field,
                        int flags)
{
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(format);
    int hsub = desc->log2_chroma_w;
    int plane, vsub = desc->log2_chroma_h;
    int k = src_field == FIELD_UPPER_AND_LOWER ? 1 : 2;
    int h;

    for (plane = 0; plane < desc->nb_components; plane++) {
        int lines = plane == 1 || plane == 2 ? AV_CEIL_RSHIFT(src_h, vsub) : src_h;
        int cols  = plane == 1 || plane == 2 ? AV_CEIL_RSHIFT(    w, hsub) : w;
        uint8_t *dstp = dst[plane];
        const uint8_t *srcp = src[plane];
        int srcp_linesize = src_linesize[plane] * k;
        int dstp_linesize = dst_linesize[plane] * (interleave ? 2 : 1);
        int clip_max = (1 << tinterlace->csp->comp[plane].depth) - 1;

        lines = (lines + (src_field == FIELD_UPPER)) / k;
        if (src_field == FIELD_LOWER)
            srcp += src_linesize[plane];
        if (interleave && dst_field == FIELD_LOWER)
            dstp += dst_linesize[plane];
        // Low-pass filtering is required when creating an interlaced destination from
        // a progressive source which contains high-frequency vertical detail.
        // Filtering will reduce interlace 'twitter' and Moire patterning.
        if (flags & (TINTERLACE_FLAG_VLPF | TINTERLACE_FLAG_CVLPF)) {
            int x = !!(flags & TINTERLACE_FLAG_CVLPF);
            for (h = lines; h > 0; h--) {
                ptrdiff_t pref = src_linesize[plane];
                ptrdiff_t mref = -pref;
                if (h >= (lines - x))  mref = 0; // there is no line above
                else if (h <= (1 + x)) pref = 0; // there is no line below

                tinterlace->lowpass_line(dstp, cols, srcp, mref, pref, clip_max);
                dstp += dstp_linesize;
                srcp += srcp_linesize;
            }
        } else {
            if (tinterlace->csp->comp[plane].depth > 8)
                cols *= 2;
            av_image_copy_plane(dstp, dstp_linesize, srcp, srcp_linesize, cols, lines);
        }
    }
}

static int filter_frame(AVFilterLink *inlink, AVFrame *picref)
{
    AVFilterContext *ctx = inlink->dst;
    AVFilterLink *outlink = ctx->outputs[0];
    TInterlaceContext *tinterlace = ctx->priv;
    AVFrame *cur, *next, *out;
    int field, tff, ret;

    av_frame_free(&tinterlace->cur);
    tinterlace->cur  = tinterlace->next;
    tinterlace->next = picref;

    cur = tinterlace->cur;
    next = tinterlace->next;
    /* we need at least two frames */
    if (!tinterlace->cur)
        return 0;

    switch (tinterlace->mode) {
    case MODE_MERGEX2: /* move the odd frame into the upper field of the new image, even into
                        * the lower field, generating a double-height video at same framerate */
    case MODE_MERGE: /* move the odd frame into the upper field of the new image, even into
             * the lower field, generating a double-height video at half framerate */
        out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
        if (!out)
            return AVERROR(ENOMEM);
        av_frame_copy_props(out, cur);
        out->height = outlink->h;
        out->interlaced_frame = 1;
        out->top_field_first = 1;
        out->sample_aspect_ratio = av_mul_q(cur->sample_aspect_ratio, av_make_q(2, 1));

        /* write odd frame lines into the upper field of the new frame */
        copy_picture_field(tinterlace, out->data, out->linesize,
                           (const uint8_t **)cur->data, cur->linesize,
                           inlink->format, inlink->w, inlink->h,
                           FIELD_UPPER_AND_LOWER, 1, tinterlace->mode == MODE_MERGEX2 ? inlink->frame_count_out & 1 ? FIELD_LOWER : FIELD_UPPER : FIELD_UPPER, tinterlace->flags);
        /* write even frame lines into the lower field of the new frame */
        copy_picture_field(tinterlace, out->data, out->linesize,
                           (const uint8_t **)next->data, next->linesize,
                           inlink->format, inlink->w, inlink->h,
                           FIELD_UPPER_AND_LOWER, 1, tinterlace->mode == MODE_MERGEX2 ? inlink->frame_count_out & 1 ? FIELD_UPPER : FIELD_LOWER : FIELD_LOWER, tinterlace->flags);
        if (tinterlace->mode != MODE_MERGEX2)
            av_frame_free(&tinterlace->next);
        break;

    case MODE_DROP_ODD:  /* only output even frames, odd  frames are dropped; height unchanged, half framerate */
    case MODE_DROP_EVEN: /* only output odd  frames, even frames are dropped; height unchanged, half framerate */
        out = av_frame_clone(tinterlace->mode == MODE_DROP_EVEN ? cur : next);
        if (!out)
            return AVERROR(ENOMEM);
        av_frame_free(&tinterlace->next);
        break;

    case MODE_PAD: /* expand each frame to double height, but pad alternate
                    * lines with black; framerate unchanged */
        out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
        if (!out)
            return AVERROR(ENOMEM);
        av_frame_copy_props(out, cur);
        out->height = outlink->h;
        out->sample_aspect_ratio = av_mul_q(cur->sample_aspect_ratio, av_make_q(2, 1));

        field = (1 + tinterlace->frame) & 1 ? FIELD_UPPER : FIELD_LOWER;
        /* copy upper and lower fields */
        copy_picture_field(tinterlace, out->data, out->linesize,
                           (const uint8_t **)cur->data, cur->linesize,
                           inlink->format, inlink->w, inlink->h,
                           FIELD_UPPER_AND_LOWER, 1, field, tinterlace->flags);
        /* pad with black the other field */
        copy_picture_field(tinterlace, out->data, out->linesize,
                           (const uint8_t **)tinterlace->black_data, tinterlace->black_linesize,
                           inlink->format, inlink->w, inlink->h,
                           FIELD_UPPER_AND_LOWER, 1, !field, tinterlace->flags);
        break;

        /* interleave upper/lower lines from odd frames with lower/upper lines from even frames,
         * halving the frame rate and preserving image height */
    case MODE_INTERLEAVE_TOP:    /* top    field first */
    case MODE_INTERLEAVE_BOTTOM: /* bottom field first */
        tff = tinterlace->mode == MODE_INTERLEAVE_TOP;
        out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
        if (!out)
            return AVERROR(ENOMEM);
        av_frame_copy_props(out, cur);
        out->interlaced_frame = 1;
        out->top_field_first = tff;

        /* copy upper/lower field from cur */
        copy_picture_field(tinterlace, out->data, out->linesize,
                           (const uint8_t **)cur->data, cur->linesize,
                           inlink->format, inlink->w, inlink->h,
                           tff ? FIELD_UPPER : FIELD_LOWER, 1, tff ? FIELD_UPPER : FIELD_LOWER,
                           tinterlace->flags);
        /* copy lower/upper field from next */
        copy_picture_field(tinterlace, out->data, out->linesize,
                           (const uint8_t **)next->data, next->linesize,
                           inlink->format, inlink->w, inlink->h,
                           tff ? FIELD_LOWER : FIELD_UPPER, 1, tff ? FIELD_LOWER : FIELD_UPPER,
                           tinterlace->flags);
        av_frame_free(&tinterlace->next);
        break;
    case MODE_INTERLACEX2: /* re-interlace preserving image height, double frame rate */
        /* output current frame first */
        out = av_frame_clone(cur);
        if (!out)
            return AVERROR(ENOMEM);
        out->interlaced_frame = 1;
        if (cur->pts != AV_NOPTS_VALUE)
            out->pts = cur->pts*2;

        out->pts = av_rescale_q(out->pts, tinterlace->preout_time_base, outlink->time_base);
        if ((ret = ff_filter_frame(outlink, out)) < 0)
            return ret;

        /* output mix of current and next frame */
        tff = next->top_field_first;
        out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
        if (!out)
            return AVERROR(ENOMEM);
        av_frame_copy_props(out, next);
        out->interlaced_frame = 1;
        out->top_field_first = !tff;

        if (next->pts != AV_NOPTS_VALUE && cur->pts != AV_NOPTS_VALUE)
            out->pts = cur->pts + next->pts;
        else
            out->pts = AV_NOPTS_VALUE;
        /* write current frame second field lines into the second field of the new frame */
        copy_picture_field(tinterlace, out->data, out->linesize,
                           (const uint8_t **)cur->data, cur->linesize,
                           inlink->format, inlink->w, inlink->h,
                           tff ? FIELD_LOWER : FIELD_UPPER, 1, tff ? FIELD_LOWER : FIELD_UPPER,
                           tinterlace->flags);
        /* write next frame first field lines into the first field of the new frame */
        copy_picture_field(tinterlace, out->data, out->linesize,
                           (const uint8_t **)next->data, next->linesize,
                           inlink->format, inlink->w, inlink->h,
                           tff ? FIELD_UPPER : FIELD_LOWER, 1, tff ? FIELD_UPPER : FIELD_LOWER,
                           tinterlace->flags);
        break;
    default:
        av_assert0(0);
    }

    out->pts = av_rescale_q(out->pts, tinterlace->preout_time_base, outlink->time_base);
    ret = ff_filter_frame(outlink, out);
    tinterlace->frame++;

    return ret;
}

static int init_interlace(AVFilterContext *ctx)
{
    TInterlaceContext *tinterlace = ctx->priv;

    if (tinterlace->mode <= MODE_BFF)
        tinterlace->mode += MODE_INTERLEAVE_TOP;

    return 0;
}

static const AVFilterPad tinterlace_inputs[] = {
    {
        .name         = "default",
        .type         = AVMEDIA_TYPE_VIDEO,
        .filter_frame = filter_frame,
    },
    { NULL }
};

static const AVFilterPad tinterlace_outputs[] = {
    {
        .name         = "default",
        .type         = AVMEDIA_TYPE_VIDEO,
        .config_props = config_out_props,
    },
    { NULL }
};

AVFilter ff_vf_tinterlace = {
    .name          = "tinterlace",
    .description   = NULL_IF_CONFIG_SMALL("Perform temporal field interlacing."),
    .priv_size     = sizeof(TInterlaceContext),
    .uninit        = uninit,
    .query_formats = query_formats,
    .inputs        = tinterlace_inputs,
    .outputs       = tinterlace_outputs,
    .priv_class    = &tinterlace_class,
};


AVFilter ff_vf_interlace = {
    .name          = "interlace",
    .description   = NULL_IF_CONFIG_SMALL("Convert progressive video into interlaced."),
    .priv_size     = sizeof(TInterlaceContext),
    .init          = init_interlace,
    .uninit        = uninit,
    .query_formats = query_formats,
    .inputs        = tinterlace_inputs,
    .outputs       = tinterlace_outputs,
    .priv_class    = &interlace_class,
};