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