1 /*
2 * MPEG-DASH ISO BMFF segmenter
3 * Copyright (c) 2014 Martin Storsjo
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "config.h"
23 #if HAVE_UNISTD_H
24 #include <unistd.h>
25 #endif
26
27 #include "libavutil/avassert.h"
28 #include "libavutil/avstring.h"
29 #include "libavutil/intreadwrite.h"
30 #include "libavutil/mathematics.h"
31 #include "libavutil/opt.h"
32 #include "libavutil/rational.h"
33 #include "libavutil/time_internal.h"
34
35 #include "avc.h"
36 #include "avformat.h"
37 #include "avio_internal.h"
38 #include "internal.h"
39 #include "isom.h"
40 #include "os_support.h"
41 #include "url.h"
42 #include "dash.h"
43
dash_read_tmpl_id(const char * identifier,char * format_tag,size_t format_tag_size,const char ** ptr)44 static DASHTmplId dash_read_tmpl_id(const char *identifier, char *format_tag,
45 size_t format_tag_size, const char **ptr) {
46 const char *next_ptr;
47 DASHTmplId id_type = DASH_TMPL_ID_UNDEFINED;
48
49 if (av_strstart(identifier, "$$", &next_ptr)) {
50 id_type = DASH_TMPL_ID_ESCAPE;
51 *ptr = next_ptr;
52 } else if (av_strstart(identifier, "$RepresentationID$", &next_ptr)) {
53 id_type = DASH_TMPL_ID_REP_ID;
54 // default to basic format, as $RepresentationID$ identifiers
55 // are not allowed to have custom format-tags.
56 av_strlcpy(format_tag, "%d", format_tag_size);
57 *ptr = next_ptr;
58 } else { // the following identifiers may have an explicit format_tag
59 if (av_strstart(identifier, "$Number", &next_ptr))
60 id_type = DASH_TMPL_ID_NUMBER;
61 else if (av_strstart(identifier, "$Bandwidth", &next_ptr))
62 id_type = DASH_TMPL_ID_BANDWIDTH;
63 else if (av_strstart(identifier, "$Time", &next_ptr))
64 id_type = DASH_TMPL_ID_TIME;
65 else
66 id_type = DASH_TMPL_ID_UNDEFINED;
67
68 // next parse the dash format-tag and generate a c-string format tag
69 // (next_ptr now points at the first '%' at the beginning of the format-tag)
70 if (id_type != DASH_TMPL_ID_UNDEFINED) {
71 const char *number_format = (id_type == DASH_TMPL_ID_TIME) ? PRId64 : "d";
72 if (next_ptr[0] == '$') { // no dash format-tag
73 snprintf(format_tag, format_tag_size, "%%%s", number_format);
74 *ptr = &next_ptr[1];
75 } else {
76 const char *width_ptr;
77 // only tolerate single-digit width-field (i.e. up to 9-digit width)
78 if (av_strstart(next_ptr, "%0", &width_ptr) &&
79 av_isdigit(width_ptr[0]) &&
80 av_strstart(&width_ptr[1], "d$", &next_ptr)) {
81 // yes, we're using a format tag to build format_tag.
82 snprintf(format_tag, format_tag_size, "%s%c%s", "%0", width_ptr[0], number_format);
83 *ptr = next_ptr;
84 } else {
85 av_log(NULL, AV_LOG_WARNING, "Failed to parse format-tag beginning with %s. Expected either a "
86 "closing '$' character or a format-string like '%%0[width]d', "
87 "where width must be a single digit\n", next_ptr);
88 id_type = DASH_TMPL_ID_UNDEFINED;
89 }
90 }
91 }
92 }
93 return id_type;
94 }
95
ff_dash_fill_tmpl_params(char * dst,size_t buffer_size,const char * template,int rep_id,int number,int bit_rate,int64_t time)96 void ff_dash_fill_tmpl_params(char *dst, size_t buffer_size,
97 const char *template, int rep_id,
98 int number, int bit_rate,
99 int64_t time) {
100 int dst_pos = 0;
101 const char *t_cur = template;
102 while (dst_pos < buffer_size - 1 && *t_cur) {
103 char format_tag[7]; // May be "%d", "%0Xd", or "%0Xlld" (for $Time$), where X is in [0-9]
104 int n = 0;
105 DASHTmplId id_type;
106 const char *t_next = strchr(t_cur, '$'); // copy over everything up to the first '$' character
107 if (t_next) {
108 int num_copy_bytes = FFMIN(t_next - t_cur, buffer_size - dst_pos - 1);
109 av_strlcpy(&dst[dst_pos], t_cur, num_copy_bytes + 1);
110 // advance
111 dst_pos += num_copy_bytes;
112 t_cur = t_next;
113 } else { // no more DASH identifiers to substitute - just copy the rest over and break
114 av_strlcpy(&dst[dst_pos], t_cur, buffer_size - dst_pos);
115 break;
116 }
117
118 if (dst_pos >= buffer_size - 1 || !*t_cur)
119 break;
120
121 // t_cur is now pointing to a '$' character
122 id_type = dash_read_tmpl_id(t_cur, format_tag, sizeof(format_tag), &t_next);
123 switch (id_type) {
124 case DASH_TMPL_ID_ESCAPE:
125 av_strlcpy(&dst[dst_pos], "$", 2);
126 n = 1;
127 break;
128 case DASH_TMPL_ID_REP_ID:
129 n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, rep_id);
130 break;
131 case DASH_TMPL_ID_NUMBER:
132 n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, number);
133 break;
134 case DASH_TMPL_ID_BANDWIDTH:
135 n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, bit_rate);
136 break;
137 case DASH_TMPL_ID_TIME:
138 n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, time);
139 break;
140 case DASH_TMPL_ID_UNDEFINED:
141 // copy over one byte and advance
142 av_strlcpy(&dst[dst_pos], t_cur, 2);
143 n = 1;
144 t_next = &t_cur[1];
145 break;
146 }
147 // t_next points just past the processed identifier
148 // n is the number of bytes that were attempted to be written to dst
149 // (may have failed to write all because buffer_size).
150
151 // advance
152 dst_pos += FFMIN(n, buffer_size - dst_pos - 1);
153 t_cur = t_next;
154 }
155 }
156
157
158