1/*
2 * Copyright (c) 2002 A'rpi
3 * This file is part of Libav.
4 *
5 * Libav is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * Libav is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License along
16 * with Libav; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20/**
21 * @file
22 * border detection filter
23 * Ported from MPlayer libmpcodecs/vf_cropdetect.c.
24 */
25
26#include "libavutil/imgutils.h"
27#include "avfilter.h"
28
29typedef struct {
30    int x1, y1, x2, y2;
31    int limit;
32    int round;
33    int reset_count;
34    int frame_nb;
35    int max_pixsteps[4];
36} CropDetectContext;
37
38static int query_formats(AVFilterContext *ctx)
39{
40    static const enum PixelFormat pix_fmts[] = {
41        PIX_FMT_YUV420P, PIX_FMT_YUVJ420P,
42        PIX_FMT_YUV422P, PIX_FMT_YUVJ422P,
43        PIX_FMT_YUV444P, PIX_FMT_YUVJ444P,
44        PIX_FMT_YUV411P, PIX_FMT_GRAY8,
45        PIX_FMT_NV12,    PIX_FMT_NV21,
46        PIX_FMT_NONE
47    };
48
49    avfilter_set_common_formats(ctx, avfilter_make_format_list(pix_fmts));
50    return 0;
51}
52
53static int checkline(void *ctx, const unsigned char *src, int stride, int len, int bpp)
54{
55    int total = 0;
56    int div = len;
57
58    switch (bpp) {
59    case 1:
60        while (--len >= 0) {
61            total += src[0];
62            src += stride;
63        }
64        break;
65    case 3:
66    case 4:
67        while (--len >= 0) {
68            total += src[0] + src[1] + src[2];
69            src += stride;
70        }
71        div *= 3;
72        break;
73    }
74    total /= div;
75
76    av_log(ctx, AV_LOG_DEBUG, "total:%d\n", total);
77    return total;
78}
79
80static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
81{
82    CropDetectContext *cd = ctx->priv;
83
84    cd->limit = 24;
85    cd->round = 0;
86    cd->reset_count = 0;
87    cd->frame_nb = -2;
88
89    if (args)
90        sscanf(args, "%d:%d:%d", &cd->limit, &cd->round, &cd->reset_count);
91
92    av_log(ctx, AV_LOG_INFO, "limit:%d round:%d reset_count:%d\n",
93           cd->limit, cd->round, cd->reset_count);
94
95    return 0;
96}
97
98static int config_input(AVFilterLink *inlink)
99{
100    AVFilterContext *ctx = inlink->dst;
101    CropDetectContext *cd = ctx->priv;
102
103    av_image_fill_max_pixsteps(cd->max_pixsteps, NULL,
104                               &av_pix_fmt_descriptors[inlink->format]);
105
106    cd->x1 = inlink->w - 1;
107    cd->y1 = inlink->h - 1;
108    cd->x2 = 0;
109    cd->y2 = 0;
110
111    return 0;
112}
113
114static void end_frame(AVFilterLink *inlink)
115{
116    AVFilterContext *ctx = inlink->dst;
117    CropDetectContext *cd = ctx->priv;
118    AVFilterBufferRef *picref = inlink->cur_buf;
119    int bpp = cd->max_pixsteps[0];
120    int w, h, x, y, shrink_by;
121
122    // ignore first 2 frames - they may be empty
123    if (++cd->frame_nb > 0) {
124        // Reset the crop area every reset_count frames, if reset_count is > 0
125        if (cd->reset_count > 0 && cd->frame_nb > cd->reset_count) {
126            cd->x1 = picref->video->w-1;
127            cd->y1 = picref->video->h-1;
128            cd->x2 = 0;
129            cd->y2 = 0;
130            cd->frame_nb = 1;
131        }
132
133        for (y = 0; y < cd->y1; y++) {
134            if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
135                cd->y1 = y;
136                break;
137            }
138        }
139
140        for (y = picref->video->h-1; y > cd->y2; y--) {
141            if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
142                cd->y2 = y;
143                break;
144            }
145        }
146
147        for (y = 0; y < cd->x1; y++) {
148            if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
149                cd->x1 = y;
150                break;
151            }
152        }
153
154        for (y = picref->video->w-1; y > cd->x2; y--) {
155            if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
156                cd->x2 = y;
157                break;
158            }
159        }
160
161        // round x and y (up), important for yuv colorspaces
162        // make sure they stay rounded!
163        x = (cd->x1+1) & ~1;
164        y = (cd->y1+1) & ~1;
165
166        w = cd->x2 - x + 1;
167        h = cd->y2 - y + 1;
168
169        // w and h must be divisible by 2 as well because of yuv
170        // colorspace problems.
171        if (cd->round <= 1)
172            cd->round = 16;
173        if (cd->round % 2)
174            cd->round *= 2;
175
176        shrink_by = w % cd->round;
177        w -= shrink_by;
178        x += (shrink_by/2 + 1) & ~1;
179
180        shrink_by = h % cd->round;
181        h -= shrink_by;
182        y += (shrink_by/2 + 1) & ~1;
183
184        av_log(ctx, AV_LOG_INFO,
185               "x1:%d x2:%d y1:%d y2:%d w:%d h:%d x:%d y:%d pos:%"PRId64" pts:%"PRId64" t:%f crop=%d:%d:%d:%d\n",
186               cd->x1, cd->x2, cd->y1, cd->y2, w, h, x, y, picref->pos, picref->pts,
187               picref->pts == AV_NOPTS_VALUE ? -1 : picref->pts * av_q2d(inlink->time_base),
188               w, h, x, y);
189    }
190
191    avfilter_end_frame(inlink->dst->outputs[0]);
192}
193
194AVFilter avfilter_vf_cropdetect = {
195    .name        = "cropdetect",
196    .description = NULL_IF_CONFIG_SMALL("Auto-detect crop size."),
197
198    .priv_size = sizeof(CropDetectContext),
199    .init      = init,
200
201    .query_formats = query_formats,
202
203    .inputs    = (AVFilterPad[]) {{ .name = "default",
204                                    .type             = AVMEDIA_TYPE_VIDEO,
205                                    .config_props     = config_input,
206                                    .get_video_buffer = avfilter_null_get_video_buffer,
207                                    .start_frame      = avfilter_null_start_frame,
208                                    .end_frame        = end_frame, },
209                                  { .name = NULL}},
210
211    .outputs   = (AVFilterPad[]) {{ .name             = "default",
212                                    .type             = AVMEDIA_TYPE_VIDEO },
213                                  { .name = NULL}},
214};
215