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 "libavutil/avstring.h"
27 #include "libavutil/eval.h"
28 #include "libavutil/mathematics.h"
29 #include "libavutil/rational.h"
30 #include "avfilter.h"
31 #include "internal.h"
32 
33 static const char *var_names[] = {
34  "E",
35  "PHI",
36  "PI",
37  "AVTB", /* default timebase 1/AV_TIME_BASE */
38  "intb", /* input timebase */
39  NULL
40 };
41 
42 enum var_name {
49 };
50 
51 typedef struct {
52  char tb_expr[256];
53  double var_values[VAR_VARS_NB];
54 } SetTBContext;
55 
56 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
57 {
58  SetTBContext *settb = ctx->priv;
59  av_strlcpy(settb->tb_expr, "intb", sizeof(settb->tb_expr));
60 
61  if (args)
62  sscanf(args, "%255[^:]", settb->tb_expr);
63 
64  return 0;
65 }
66 
67 static int config_output_props(AVFilterLink *outlink)
68 {
69  AVFilterContext *ctx = outlink->src;
70  SetTBContext *settb = ctx->priv;
71  AVFilterLink *inlink = ctx->inputs[0];
72  AVRational time_base;
73  int ret;
74  double res;
75 
76  settb->var_values[VAR_E] = M_E;
77  settb->var_values[VAR_PHI] = M_PHI;
78  settb->var_values[VAR_PI] = M_PI;
80  settb->var_values[VAR_INTB] = av_q2d(inlink->time_base);
81 
82  outlink->w = inlink->w;
83  outlink->h = inlink->h;
84 
85  if ((ret = av_expr_parse_and_eval(&res, settb->tb_expr, var_names, settb->var_values,
86  NULL, NULL, NULL, NULL, NULL, 0, NULL)) < 0) {
87  av_log(ctx, AV_LOG_ERROR, "Invalid expression '%s' for timebase.\n", settb->tb_expr);
88  return ret;
89  }
90  time_base = av_d2q(res, INT_MAX);
91  if (time_base.num <= 0 || time_base.den <= 0) {
92  av_log(ctx, AV_LOG_ERROR,
93  "Invalid non-positive values for the timebase num:%d or den:%d.\n",
94  time_base.num, time_base.den);
95  return AVERROR(EINVAL);
96  }
97 
98  outlink->time_base = time_base;
99  av_log(outlink->src, AV_LOG_INFO, "tb:%d/%d -> tb:%d/%d\n",
100  inlink ->time_base.num, inlink ->time_base.den,
101  outlink->time_base.num, outlink->time_base.den);
102 
103  return 0;
104 }
105 
106 static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
107 {
108  AVFilterContext *ctx = inlink->dst;
109  AVFilterLink *outlink = ctx->outputs[0];
110  AVFilterBufferRef *picref2 = picref;
111 
112  if (av_cmp_q(inlink->time_base, outlink->time_base)) {
113  picref2 = avfilter_ref_buffer(picref, ~0);
114  picref2->pts = av_rescale_q(picref->pts, inlink->time_base, outlink->time_base);
115  av_log(ctx, AV_LOG_DEBUG, "tb:%d/%d pts:%"PRId64" -> tb:%d/%d pts:%"PRId64"\n",
116  inlink ->time_base.num, inlink ->time_base.den, picref ->pts,
117  outlink->time_base.num, outlink->time_base.den, picref2->pts);
118  avfilter_unref_buffer(picref);
119  }
120 
121  avfilter_start_frame(outlink, picref2);
122 }
123 
125  .name = "settb",
126  .description = NULL_IF_CONFIG_SMALL("Set timebase for the output link."),
127  .init = init,
128 
129  .priv_size = sizeof(SetTBContext),
130 
131  .inputs = (AVFilterPad[]) {{ .name = "default",
132  .type = AVMEDIA_TYPE_VIDEO,
133  .get_video_buffer = avfilter_null_get_video_buffer,
134  .start_frame = start_frame,
135  .end_frame = avfilter_null_end_frame },
136  { .name = NULL }},
137 
138  .outputs = (AVFilterPad[]) {{ .name = "default",
139  .type = AVMEDIA_TYPE_VIDEO,
140  .config_props = config_output_props, },
141  { .name = NULL}},
142 };