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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 { | |
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 *dj = 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 * dj->cycle)); | |
87 | outlink->frame_rate = av_mul_q(inlink->frame_rate, av_make_q(2 * dj->cycle, 1)); | |
88 | ||
89 | av_log(ctx, AV_LOG_VERBOSE, "cycle:%d\n", dj->cycle); | |
90 | ||
91 | return 0; | |
92 | } | |
93 | ||
94 | static av_cold int dejudder_init(AVFilterContext *ctx) | |
95 | { | |
96 | DejudderContext *dj = ctx->priv; | |
97 | ||
98 | dj->ringbuff = av_mallocz_array(dj->cycle+2, sizeof(*dj->ringbuff)); | |
99 | if (!dj->ringbuff) | |
100 | return AVERROR(ENOMEM); | |
101 | ||
102 | dj->new_pts = 0; | |
103 | dj->i1 = 0; | |
104 | dj->i2 = 1; | |
105 | dj->i3 = 2; | |
106 | dj->i4 = 3; | |
107 | dj->start_count = dj->cycle + 2; | |
108 | ||
109 | return 0; | |
110 | } | |
111 | ||
112 | static av_cold void dejudder_uninit(AVFilterContext *ctx) | |
113 | { | |
114 | DejudderContext *dj = ctx->priv; | |
115 | ||
116 | av_freep(&(dj->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 *dj = ctx->priv; | |
125 | int64_t *judbuff = dj->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 (dj->start_count) { | |
133 | dj->start_count--; | |
134 | dj->new_pts = next_pts * 2 * dj->cycle; | |
135 | } else { | |
136 | if (next_pts < judbuff[dj->i2]) { | |
137 | offset = next_pts + judbuff[dj->i3] - judbuff[dj->i4] - judbuff[dj->i1]; | |
138 | for (k = 0; k < dj->cycle + 2; k++) | |
139 | judbuff[k] += offset; | |
140 | } | |
141 | dj->new_pts += (dj->cycle - 1) * (judbuff[dj->i3] - judbuff[dj->i1]) | |
142 | + (dj->cycle + 1) * (next_pts - judbuff[dj->i4]); | |
143 | } | |
144 | ||
145 | judbuff[dj->i2] = next_pts; | |
146 | dj->i1 = dj->i2; | |
147 | dj->i2 = dj->i3; | |
148 | dj->i3 = dj->i4; | |
149 | dj->i4 = (dj->i4 + 1) % (dj->cycle + 2); | |
150 | ||
151 | frame->pts = dj->new_pts; | |
152 | ||
153 | for (k = 0; k < dj->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 | }; |