blob: c4d7b6bb6cc76c5e1e203cbabc5d9de7b94f159c
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 *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 | }; |
188 |