| 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 | }; |