aboutsummaryrefslogtreecommitdiffstats
path: root/libavfilter/vf_tinterlace.c
blob: 63f1fc72f2ac8443834a25aaff7260984d00a7b5 (plain) (blame)
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
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
/*
 * 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" },
    {"bypass_il",         "bypass already interlaced frames",             0, AV_OPT_TYPE_CONST, {.i64 = TINTERLACE_FLAG_BYPASS_IL}, 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(lowpass), AV_OPT_TYPE_INT,   {.i64 = VLPF_LIN}, 0, 2, FLAGS, "lowpass" },
   {     "off",           "disable vertical low-pass filter",             0, AV_OPT_TYPE_CONST, {.i64 = VLPF_OFF}, INT_MIN, INT_MAX, FLAGS, "lowpass" },
   {     "linear",        "linear vertical low-pass filter",              0, AV_OPT_TYPE_CONST, {.i64 = VLPF_LIN}, INT_MIN, INT_MAX, FLAGS, "lowpass" },
   {     "complex",       "complex vertical low-pass filter",             0, AV_OPT_TYPE_CONST, {.i64 = VLPF_CMP}, INT_MIN, INT_MAX, FLAGS, "lowpass" },

   { 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 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
};

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][0]);
    av_freep(&tinterlace->black_data[1][0]);
    ff_ccfifo_uninit(&tinterlace->cc_fifo);
}

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 ret, 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 };
        ff_draw_init(&tinterlace->draw, outlink->format, 0);
        ff_draw_color(&tinterlace->draw, &tinterlace->color, black);
        /* limited range */
        if (!ff_fmt_is_in(outlink->format, full_scale_yuvj_pix_fmts)) {
            ret = av_image_alloc(tinterlace->black_data[0], 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[0],
                              tinterlace->black_linesize, 0, 0, outlink->w, outlink->h);
        }
        /* full range */
        tinterlace->color.comp[0].u8[0] = 0;
        ret = av_image_alloc(tinterlace->black_data[1], 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[1],
                          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);
#endif
    } 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);
#endif
    }

    ret = ff_ccfifo_init(&tinterlace->cc_fifo, outlink->frame_rate, ctx);
    if (ret < 0) {
        av_log(ctx, AV_LOG_ERROR, "Failure to setup CC FIFO queue\n");
        return ret;
    }

    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, full, ret;

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

    ff_ccfifo_extract(&tinterlace->cc_fifo, 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;
#if FF_API_INTERLACED_FRAME
FF_DISABLE_DEPRECATION_WARNINGS
        out->interlaced_frame = 1;
        out->top_field_first = 1;
FF_ENABLE_DEPRECATION_WARNINGS
#endif
        out->flags |= AV_FRAME_FLAG_INTERLACED | AV_FRAME_FLAG_TOP_FIELD_FIRST;
        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 ? (1 + 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 ? (1 + 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 + outlink->frame_count_in) & 1 ? FIELD_UPPER : FIELD_LOWER;
        full = out->color_range == AVCOL_RANGE_JPEG || ff_fmt_is_in(out->format, full_scale_yuvj_pix_fmts);
        /* 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[full], 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 */
        if ((tinterlace->flags & TINTERLACE_FLAG_BYPASS_IL) && (cur->flags & AV_FRAME_FLAG_INTERLACED)) {
            av_log(ctx, AV_LOG_WARNING,
                   "video is already interlaced, adjusting framerate only\n");
            out = av_frame_clone(cur);
            if (!out)
                return AVERROR(ENOMEM);
            out->pts /= 2;  // adjust pts to new framerate
            ff_ccfifo_inject(&tinterlace->cc_fifo, out);
            ret = ff_filter_frame(outlink, out);
            return ret;
        }
        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);
#if FF_API_INTERLACED_FRAME
FF_DISABLE_DEPRECATION_WARNINGS
        out->interlaced_frame = 1;
        out->top_field_first = tff;
FF_ENABLE_DEPRECATION_WARNINGS
#endif
        out->flags |= AV_FRAME_FLAG_INTERLACED;
        if (tff)
            out->flags |= AV_FRAME_FLAG_TOP_FIELD_FIRST;
        else
            out->flags &= ~AV_FRAME_FLAG_TOP_FIELD_FIRST;

        /* 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);
#if FF_API_INTERLACED_FRAME
FF_DISABLE_DEPRECATION_WARNINGS
        out->interlaced_frame = 1;
FF_ENABLE_DEPRECATION_WARNINGS
#endif
        out->flags |= AV_FRAME_FLAG_INTERLACED;
        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);
        ff_ccfifo_inject(&tinterlace->cc_fifo, out);
        if ((ret = ff_filter_frame(outlink, out)) < 0)
            return ret;

        /* output mix of current and next frame */
        tff = !!(next->flags & AV_FRAME_FLAG_TOP_FIELD_FIRST);
        out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
        if (!out)
            return AVERROR(ENOMEM);
        av_frame_copy_props(out, next);
#if FF_API_INTERLACED_FRAME
FF_DISABLE_DEPRECATION_WARNINGS
        out->interlaced_frame = 1;
        out->top_field_first = !tff;
FF_ENABLE_DEPRECATION_WARNINGS
#endif
        out->flags |= AV_FRAME_FLAG_INTERLACED;
        if (tff)
            out->flags &= ~AV_FRAME_FLAG_TOP_FIELD_FIRST;
        else
            out->flags |= AV_FRAME_FLAG_TOP_FIELD_FIRST;

        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);
    out->duration = av_rescale_q(1, av_inv_q(outlink->frame_rate), outlink->time_base);
    ff_ccfifo_inject(&tinterlace->cc_fifo, out);
    ret = ff_filter_frame(outlink, out);

    return ret;
}

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

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

    tinterlace->flags |= TINTERLACE_FLAG_BYPASS_IL;
    if (tinterlace->lowpass == VLPF_LIN)
        tinterlace->flags |= TINTERLACE_FLAG_VLPF;
    if (tinterlace->lowpass == VLPF_CMP)
        tinterlace->flags |= TINTERLACE_FLAG_CVLPF;

    return 0;
}

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

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

const AVFilter ff_vf_tinterlace = {
    .name          = "tinterlace",
    .description   = NULL_IF_CONFIG_SMALL("Perform temporal field interlacing."),
    .priv_size     = sizeof(TInterlaceContext),
    .uninit        = uninit,
    FILTER_INPUTS(tinterlace_inputs),
    FILTER_OUTPUTS(tinterlace_outputs),
    FILTER_PIXFMTS_ARRAY(pix_fmts),
    .priv_class    = &tinterlace_class,
};


const 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,
    FILTER_INPUTS(tinterlace_inputs),
    FILTER_OUTPUTS(tinterlace_outputs),
    FILTER_PIXFMTS_ARRAY(pix_fmts),
    .priv_class    = &interlace_class,
};