158 lines
6.2 KiB
C
158 lines
6.2 KiB
C
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/*
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* MPEG-DASH ISO BMFF segmenter
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* Copyright (c) 2014 Martin Storsjo
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "config.h"
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include "libavutil/avassert.h"
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#include "libavutil/avstring.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/mathematics.h"
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#include "libavutil/opt.h"
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#include "libavutil/rational.h"
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#include "libavutil/time_internal.h"
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#include "avc.h"
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#include "avformat.h"
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#include "avio_internal.h"
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#include "internal.h"
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#include "isom.h"
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#include "os_support.h"
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#include "url.h"
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#include "dash.h"
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static DASHTmplId dash_read_tmpl_id(const char *identifier, char *format_tag,
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size_t format_tag_size, const char **ptr) {
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const char *next_ptr;
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DASHTmplId id_type = DASH_TMPL_ID_UNDEFINED;
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if (av_strstart(identifier, "$$", &next_ptr)) {
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id_type = DASH_TMPL_ID_ESCAPE;
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*ptr = next_ptr;
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} else if (av_strstart(identifier, "$RepresentationID$", &next_ptr)) {
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id_type = DASH_TMPL_ID_REP_ID;
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// default to basic format, as $RepresentationID$ identifiers
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// are not allowed to have custom format-tags.
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av_strlcpy(format_tag, "%d", format_tag_size);
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*ptr = next_ptr;
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} else { // the following identifiers may have an explicit format_tag
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if (av_strstart(identifier, "$Number", &next_ptr))
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id_type = DASH_TMPL_ID_NUMBER;
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else if (av_strstart(identifier, "$Bandwidth", &next_ptr))
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id_type = DASH_TMPL_ID_BANDWIDTH;
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else if (av_strstart(identifier, "$Time", &next_ptr))
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id_type = DASH_TMPL_ID_TIME;
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else
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id_type = DASH_TMPL_ID_UNDEFINED;
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// next parse the dash format-tag and generate a c-string format tag
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// (next_ptr now points at the first '%' at the beginning of the format-tag)
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if (id_type != DASH_TMPL_ID_UNDEFINED) {
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const char *number_format = (id_type == DASH_TMPL_ID_TIME) ? PRId64 : "d";
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if (next_ptr[0] == '$') { // no dash format-tag
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snprintf(format_tag, format_tag_size, "%%%s", number_format);
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*ptr = &next_ptr[1];
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} else {
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const char *width_ptr;
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// only tolerate single-digit width-field (i.e. up to 9-digit width)
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if (av_strstart(next_ptr, "%0", &width_ptr) &&
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av_isdigit(width_ptr[0]) &&
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av_strstart(&width_ptr[1], "d$", &next_ptr)) {
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// yes, we're using a format tag to build format_tag.
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snprintf(format_tag, format_tag_size, "%s%c%s", "%0", width_ptr[0], number_format);
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*ptr = next_ptr;
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} else {
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av_log(NULL, AV_LOG_WARNING, "Failed to parse format-tag beginning with %s. Expected either a "
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"closing '$' character or a format-string like '%%0[width]d', "
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"where width must be a single digit\n", next_ptr);
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id_type = DASH_TMPL_ID_UNDEFINED;
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}
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}
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}
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}
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return id_type;
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}
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void ff_dash_fill_tmpl_params(char *dst, size_t buffer_size,
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const char *template, int rep_id,
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int number, int bit_rate,
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int64_t time) {
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int dst_pos = 0;
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const char *t_cur = template;
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while (dst_pos < buffer_size - 1 && *t_cur) {
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char format_tag[7]; // May be "%d", "%0Xd", or "%0Xlld" (for $Time$), where X is in [0-9]
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int n = 0;
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DASHTmplId id_type;
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const char *t_next = strchr(t_cur, '$'); // copy over everything up to the first '$' character
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if (t_next) {
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int num_copy_bytes = FFMIN(t_next - t_cur, buffer_size - dst_pos - 1);
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av_strlcpy(&dst[dst_pos], t_cur, num_copy_bytes + 1);
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// advance
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dst_pos += num_copy_bytes;
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t_cur = t_next;
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} else { // no more DASH identifiers to substitute - just copy the rest over and break
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av_strlcpy(&dst[dst_pos], t_cur, buffer_size - dst_pos);
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break;
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}
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if (dst_pos >= buffer_size - 1 || !*t_cur)
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break;
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// t_cur is now pointing to a '$' character
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id_type = dash_read_tmpl_id(t_cur, format_tag, sizeof(format_tag), &t_next);
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switch (id_type) {
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case DASH_TMPL_ID_ESCAPE:
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av_strlcpy(&dst[dst_pos], "$", 2);
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n = 1;
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break;
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case DASH_TMPL_ID_REP_ID:
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n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, rep_id);
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break;
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case DASH_TMPL_ID_NUMBER:
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n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, number);
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break;
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case DASH_TMPL_ID_BANDWIDTH:
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n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, bit_rate);
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break;
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case DASH_TMPL_ID_TIME:
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n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, time);
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break;
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case DASH_TMPL_ID_UNDEFINED:
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// copy over one byte and advance
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av_strlcpy(&dst[dst_pos], t_cur, 2);
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n = 1;
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t_next = &t_cur[1];
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break;
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}
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// t_next points just past the processed identifier
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// n is the number of bytes that were attempted to be written to dst
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// (may have failed to write all because buffer_size).
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// advance
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dst_pos += FFMIN(n, buffer_size - dst_pos - 1);
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t_cur = t_next;
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}
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}
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