/* * TTML subtitle muxer * Copyright (c) 2020 24i * * 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 */ /** * @file * TTML subtitle muxer * @see https://www.w3.org/TR/ttml1/ * @see https://www.w3.org/TR/ttml2/ * @see https://www.w3.org/TR/ttml-imsc/rec */ #include "libavutil/avstring.h" #include "avformat.h" #include "internal.h" #include "mux.h" #include "ttmlenc.h" #include "libavcodec/ttmlenc.h" #include "libavutil/internal.h" enum TTMLPacketType { PACKET_TYPE_PARAGRAPH, PACKET_TYPE_DOCUMENT, }; struct TTMLHeaderParameters { const char *tt_element_params; const char *pre_body_elements; }; typedef struct TTMLMuxContext { enum TTMLPacketType input_type; unsigned int document_written; } TTMLMuxContext; static const char ttml_header_text[] = "\n" "\n" "%s" " \n" "

\n"; static const char ttml_footer_text[] = "

\n" " \n" "\n"; static void ttml_write_time(AVIOContext *pb, const char tag[], int64_t millisec) { int64_t sec, min, hour; sec = millisec / 1000; millisec -= 1000 * sec; min = sec / 60; sec -= 60 * min; hour = min / 60; min -= 60 * hour; avio_printf(pb, "%s=\"%02"PRId64":%02"PRId64":%02"PRId64".%03"PRId64"\"", tag, hour, min, sec, millisec); } static int ttml_set_header_values_from_extradata( AVCodecParameters *par, struct TTMLHeaderParameters *header_params) { size_t additional_data_size = par->extradata_size - TTMLENC_EXTRADATA_SIGNATURE_SIZE; char *value = (char *)par->extradata + TTMLENC_EXTRADATA_SIGNATURE_SIZE; size_t value_size = av_strnlen(value, additional_data_size); struct TTMLHeaderParameters local_params = { 0 }; if (!additional_data_size) { // simple case, we don't have to go through local_params and just // set default fall-back values (for old extradata format). header_params->tt_element_params = TTML_DEFAULT_NAMESPACING; header_params->pre_body_elements = ""; return 0; } if (value_size == additional_data_size || value[value_size] != '\0') return AVERROR_INVALIDDATA; local_params.tt_element_params = value; additional_data_size -= value_size + 1; value += value_size + 1; if (!additional_data_size) return AVERROR_INVALIDDATA; value_size = av_strnlen(value, additional_data_size); if (value_size == additional_data_size || value[value_size] != '\0') return AVERROR_INVALIDDATA; local_params.pre_body_elements = value; *header_params = local_params; return 0; } static int ttml_write_header(AVFormatContext *ctx) { TTMLMuxContext *ttml_ctx = ctx->priv_data; ttml_ctx->document_written = 0; if (ctx->nb_streams != 1 || ctx->streams[0]->codecpar->codec_id != AV_CODEC_ID_TTML) { av_log(ctx, AV_LOG_ERROR, "Exactly one TTML stream is required!\n"); return AVERROR(EINVAL); } { AVStream *st = ctx->streams[0]; AVIOContext *pb = ctx->pb; AVDictionaryEntry *lang = av_dict_get(st->metadata, "language", NULL, 0); const char *printed_lang = (lang && lang->value) ? lang->value : ""; ttml_ctx->input_type = ff_is_ttml_stream_paragraph_based(st->codecpar) ? PACKET_TYPE_PARAGRAPH : PACKET_TYPE_DOCUMENT; avpriv_set_pts_info(st, 64, 1, 1000); if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) { struct TTMLHeaderParameters header_params; int ret = ttml_set_header_values_from_extradata( st->codecpar, &header_params); if (ret < 0) { av_log(ctx, AV_LOG_ERROR, "Failed to parse TTML header values from extradata: " "%s!\n", av_err2str(ret)); return ret; } avio_printf(pb, ttml_header_text, header_params.tt_element_params, printed_lang, header_params.pre_body_elements); } } return 0; } static int ttml_write_packet(AVFormatContext *ctx, AVPacket *pkt) { TTMLMuxContext *ttml_ctx = ctx->priv_data; AVIOContext *pb = ctx->pb; switch (ttml_ctx->input_type) { case PACKET_TYPE_PARAGRAPH: // write out a paragraph element with the given contents. avio_printf(pb, " pts); avio_w8(pb, '\n'); ttml_write_time(pb, " end", pkt->pts + pkt->duration); avio_printf(pb, ">"); avio_write(pb, pkt->data, pkt->size); avio_printf(pb, "

\n"); break; case PACKET_TYPE_DOCUMENT: // dump the given document out as-is. if (ttml_ctx->document_written) { av_log(ctx, AV_LOG_ERROR, "Attempting to write multiple TTML documents into a " "single document! The XML specification forbids this " "as there has to be a single root tag.\n"); return AVERROR(EINVAL); } avio_write(pb, pkt->data, pkt->size); ttml_ctx->document_written = 1; break; default: av_log(ctx, AV_LOG_ERROR, "Internal error: invalid TTML input packet type: %d!\n", ttml_ctx->input_type); return AVERROR_BUG; } return 0; } static int ttml_write_trailer(AVFormatContext *ctx) { TTMLMuxContext *ttml_ctx = ctx->priv_data; AVIOContext *pb = ctx->pb; if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) avio_printf(pb, ttml_footer_text); return 0; } const FFOutputFormat ff_ttml_muxer = { .p.name = "ttml", .p.long_name = NULL_IF_CONFIG_SMALL("TTML subtitle"), .p.extensions = "ttml", .p.mime_type = "text/ttml", .priv_data_size = sizeof(TTMLMuxContext), .p.flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT, .p.subtitle_codec = AV_CODEC_ID_TTML, .write_header = ttml_write_header, .write_packet = ttml_write_packet, .write_trailer = ttml_write_trailer, };