FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavfilter/vf_dejudder.c
Date: 2022-12-05 20:26:17
Exec Total Coverage
Lines: 0 50 0.0%
Functions: 0 4 0.0%
Branches: 0 12 0.0%

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1 /*
2 * Copyright (c) 2014 Nicholas Robbins
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file
23 * remove judder in video stream
24 *
25 * Algorithm:
26 * - If the old packets had PTS of old_pts[i]. Replace these with new
27 * value based on the running average of the last n=cycle frames. So
28 *
29 * new_pts[i] = Sum(k=i-n+1, i, old_pts[k])/n
30 * + (old_pts[i]-old_pts[i-n])*(n-1)/2n
31 *
32 * For any repeating pattern of length n of judder this will produce
33 * an even progression of PTS's.
34 *
35 * - In order to avoid calculating this sum ever frame, a running tally
36 * is maintained in ctx->new_pts. Each frame the new term at the start
37 * of the sum is added, the one and the end is removed, and the offset
38 * terms (second line in formula above) are recalculated.
39 *
40 * - To aid in this a ringbuffer of the last n-2 PTS's is maintained in
41 * ctx->ringbuff. With the indices of the first two and last two entries
42 * stored in i1, i2, i3, & i4.
43 *
44 * - To ensure that the new PTS's are integers, time_base is divided
45 * by 2n. This removes the division in the new_pts calculation.
46 *
47 * - frame_rate is also multiplied by 2n to allow the frames to fall
48 * where they may in what may now be a VFR output. This produces more
49 * even output then setting frame_rate=1/0 in practice.
50 */
51
52 #include "libavutil/opt.h"
53 #include "libavutil/mathematics.h"
54 #include "avfilter.h"
55 #include "internal.h"
56 #include "video.h"
57
58 typedef struct DejudderContext {
59 const AVClass *class;
60 int64_t *ringbuff;
61 int i1, i2, i3, i4;
62 int64_t new_pts;
63 int start_count;
64
65 /* options */
66 int cycle;
67 } DejudderContext;
68
69 #define OFFSET(x) offsetof(DejudderContext, x)
70 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM | AV_OPT_FLAG_VIDEO_PARAM
71
72 static const AVOption dejudder_options[] = {
73 {"cycle", "set the length of the cycle to use for dejuddering",
74 OFFSET(cycle), AV_OPT_TYPE_INT, {.i64 = 4}, 2, 240, .flags = FLAGS},
75 {NULL}
76 };
77
78 AVFILTER_DEFINE_CLASS(dejudder);
79
80 static int config_out_props(AVFilterLink *outlink)
81 {
82 AVFilterContext *ctx = outlink->src;
83 DejudderContext *s = ctx->priv;
84 AVFilterLink *inlink = outlink->src->inputs[0];
85
86 outlink->time_base = av_mul_q(inlink->time_base, av_make_q(1, 2 * s->cycle));
87 outlink->frame_rate = av_mul_q(inlink->frame_rate, av_make_q(2 * s->cycle, 1));
88
89 av_log(ctx, AV_LOG_VERBOSE, "cycle:%d\n", s->cycle);
90
91 return 0;
92 }
93
94 static av_cold int dejudder_init(AVFilterContext *ctx)
95 {
96 DejudderContext *s = ctx->priv;
97
98 s->ringbuff = av_calloc(s->cycle + 2, sizeof(*s->ringbuff));
99 if (!s->ringbuff)
100 return AVERROR(ENOMEM);
101
102 s->new_pts = 0;
103 s->i1 = 0;
104 s->i2 = 1;
105 s->i3 = 2;
106 s->i4 = 3;
107 s->start_count = s->cycle + 2;
108
109 return 0;
110 }
111
112 static av_cold void dejudder_uninit(AVFilterContext *ctx)
113 {
114 DejudderContext *s = ctx->priv;
115
116 av_freep(&(s->ringbuff));
117 }
118
119 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
120 {
121 int k;
122 AVFilterContext *ctx = inlink->dst;
123 AVFilterLink *outlink = ctx->outputs[0];
124 DejudderContext *s = ctx->priv;
125 int64_t *judbuff = s->ringbuff;
126 int64_t next_pts = frame->pts;
127 int64_t offset;
128
129 if (next_pts == AV_NOPTS_VALUE)
130 return ff_filter_frame(outlink, frame);
131
132 if (s->start_count) {
133 s->start_count--;
134 s->new_pts = next_pts * 2 * s->cycle;
135 } else {
136 if (next_pts < judbuff[s->i2]) {
137 offset = next_pts + judbuff[s->i3] - judbuff[s->i4] - judbuff[s->i1];
138 for (k = 0; k < s->cycle + 2; k++)
139 judbuff[k] += offset;
140 }
141 s->new_pts += (s->cycle - 1) * (judbuff[s->i3] - judbuff[s->i1])
142 + (s->cycle + 1) * (next_pts - judbuff[s->i4]);
143 }
144
145 judbuff[s->i2] = next_pts;
146 s->i1 = s->i2;
147 s->i2 = s->i3;
148 s->i3 = s->i4;
149 s->i4 = (s->i4 + 1) % (s->cycle + 2);
150
151 frame->pts = s->new_pts;
152
153 for (k = 0; k < s->cycle + 2; k++)
154 av_log(ctx, AV_LOG_DEBUG, "%"PRId64"\t", judbuff[k]);
155 av_log(ctx, AV_LOG_DEBUG, "next=%"PRId64", new=%"PRId64"\n", next_pts, frame->pts);
156
157 return ff_filter_frame(outlink, frame);
158 }
159
160 static const AVFilterPad dejudder_inputs[] = {
161 {
162 .name = "default",
163 .type = AVMEDIA_TYPE_VIDEO,
164 .filter_frame = filter_frame,
165 },
166 };
167
168 static const AVFilterPad dejudder_outputs[] = {
169 {
170 .name = "default",
171 .type = AVMEDIA_TYPE_VIDEO,
172 .config_props = config_out_props,
173 },
174 };
175
176 const AVFilter ff_vf_dejudder = {
177 .name = "dejudder",
178 .description = NULL_IF_CONFIG_SMALL("Remove judder produced by pullup."),
179 .priv_size = sizeof(DejudderContext),
180 .priv_class = &dejudder_class,
181 FILTER_INPUTS(dejudder_inputs),
182 FILTER_OUTPUTS(dejudder_outputs),
183 .init = dejudder_init,
184 .uninit = dejudder_uninit,
185 };
186