Libav
vf_settb.c
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1 /*
2  * Copyright (c) 2010 Stefano Sabatini
3  *
4  * This file is part of Libav.
5  *
6  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
26 #include <inttypes.h>
27 #include <stdio.h>
28 
29 #include "libavutil/avstring.h"
30 #include "libavutil/eval.h"
31 #include "libavutil/internal.h"
32 #include "libavutil/mathematics.h"
33 #include "libavutil/opt.h"
34 #include "libavutil/rational.h"
35 #include "avfilter.h"
36 #include "internal.h"
37 #include "video.h"
38 
39 static const char *const var_names[] = {
40  "E",
41  "PHI",
42  "PI",
43  "AVTB", /* default timebase 1/AV_TIME_BASE */
44  "intb", /* input timebase */
45  NULL
46 };
47 
48 enum var_name {
55 };
56 
57 typedef struct {
58  const AVClass *class;
59  char *tb_expr;
60  double var_values[VAR_VARS_NB];
61 } SetTBContext;
62 
63 static int config_output_props(AVFilterLink *outlink)
64 {
65  AVFilterContext *ctx = outlink->src;
66  SetTBContext *settb = ctx->priv;
67  AVFilterLink *inlink = ctx->inputs[0];
68  AVRational time_base;
69  int ret;
70  double res;
71 
72  settb->var_values[VAR_E] = M_E;
73  settb->var_values[VAR_PHI] = M_PHI;
74  settb->var_values[VAR_PI] = M_PI;
76  settb->var_values[VAR_INTB] = av_q2d(inlink->time_base);
77 
78  outlink->w = inlink->w;
79  outlink->h = inlink->h;
80 
81  if ((ret = av_expr_parse_and_eval(&res, settb->tb_expr, var_names, settb->var_values,
82  NULL, NULL, NULL, NULL, NULL, 0, NULL)) < 0) {
83  av_log(ctx, AV_LOG_ERROR, "Invalid expression '%s' for timebase.\n", settb->tb_expr);
84  return ret;
85  }
86  time_base = av_d2q(res, INT_MAX);
87  if (time_base.num <= 0 || time_base.den <= 0) {
88  av_log(ctx, AV_LOG_ERROR,
89  "Invalid non-positive values for the timebase num:%d or den:%d.\n",
90  time_base.num, time_base.den);
91  return AVERROR(EINVAL);
92  }
93 
94  outlink->time_base = time_base;
95  av_log(outlink->src, AV_LOG_VERBOSE, "tb:%d/%d -> tb:%d/%d\n",
96  inlink ->time_base.num, inlink ->time_base.den,
97  outlink->time_base.num, outlink->time_base.den);
98 
99  return 0;
100 }
101 
102 static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
103 {
104  AVFilterContext *ctx = inlink->dst;
105  AVFilterLink *outlink = ctx->outputs[0];
106 
107  if (av_cmp_q(inlink->time_base, outlink->time_base)) {
108  int64_t orig_pts = frame->pts;
109  frame->pts = av_rescale_q(frame->pts, inlink->time_base, outlink->time_base);
110  av_log(ctx, AV_LOG_DEBUG, "tb:%d/%d pts:%"PRId64" -> tb:%d/%d pts:%"PRId64"\n",
111  inlink ->time_base.num, inlink ->time_base.den, orig_pts,
112  outlink->time_base.num, outlink->time_base.den, frame->pts);
113  }
114 
115  return ff_filter_frame(outlink, frame);
116 }
117 
118 #define OFFSET(x) offsetof(SetTBContext, x)
119 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM
120 static const AVOption options[] = {
121  { "expr", "Expression determining the output timebase", OFFSET(tb_expr), AV_OPT_TYPE_STRING, { .str = "intb" }, .flags = FLAGS },
122  { NULL },
123 };
124 
125 static const AVClass settb_class = {
126  .class_name = "settb",
127  .item_name = av_default_item_name,
128  .option = options,
129  .version = LIBAVUTIL_VERSION_INT,
130 };
131 
133  {
134  .name = "default",
135  .type = AVMEDIA_TYPE_VIDEO,
136  .get_video_buffer = ff_null_get_video_buffer,
137  .filter_frame = filter_frame,
138  },
139  { NULL }
140 };
141 
143  {
144  .name = "default",
145  .type = AVMEDIA_TYPE_VIDEO,
146  .config_props = config_output_props,
147  },
148  { NULL }
149 };
150 
152  .name = "settb",
153  .description = NULL_IF_CONFIG_SMALL("Set timebase for the output link."),
154 
155  .priv_size = sizeof(SetTBContext),
156  .priv_class = &settb_class,
157 
158  .inputs = avfilter_vf_settb_inputs,
159 
160  .outputs = avfilter_vf_settb_outputs,
161 };