GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavfilter/vf_dejudder.c Lines: 0 50 0.0 %
Date: 2020-08-14 10:39:37 Branches: 0 12 0.0 %

Line Branch Exec Source
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_mallocz_array(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
    { NULL }
167
};
168
169
static const AVFilterPad dejudder_outputs[] = {
170
    {
171
        .name = "default",
172
        .type = AVMEDIA_TYPE_VIDEO,
173
        .config_props = config_out_props,
174
    },
175
    { NULL }
176
};
177
178
AVFilter ff_vf_dejudder = {
179
    .name        = "dejudder",
180
    .description = NULL_IF_CONFIG_SMALL("Remove judder produced by pullup."),
181
    .priv_size   = sizeof(DejudderContext),
182
    .priv_class  = &dejudder_class,
183
    .inputs      = dejudder_inputs,
184
    .outputs     = dejudder_outputs,
185
    .init        = dejudder_init,
186
    .uninit      = dejudder_uninit,
187
};