diff options
Diffstat (limited to 'libavformat/ttmlenc.c')
| -rw-r--r-- | libavformat/ttmlenc.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/libavformat/ttmlenc.c b/libavformat/ttmlenc.c new file mode 100644 index 0000000000..940f8bbd4e --- /dev/null +++ b/libavformat/ttmlenc.c @@ -0,0 +1,174 @@ +/* + * 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 "avformat.h" +#include "internal.h" +#include "libavcodec/ttmlenc.h" +#include "libavutil/internal.h" + +enum TTMLPacketType { + PACKET_TYPE_PARAGRAPH, + PACKET_TYPE_DOCUMENT, +}; + +typedef struct TTMLMuxContext { + enum TTMLPacketType input_type; + unsigned int document_written; +} TTMLMuxContext; + +static const char ttml_header_text[] = +"<?xml version=\"1.0\" encoding=\"utf-8\"?>\n" +"<tt\n" +" xmlns=\"http://www.w3.org/ns/ttml\"\n" +" xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"\n" +" xmlns:tts=\"http://www.w3.org/ns/ttml#styling\"\n" +" xml:lang=\"%s\">\n" +" <body>\n" +" <div>\n"; + +static const char ttml_footer_text[] = +" </div>\n" +" </body>\n" +"</tt>\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_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 : ""; + + // Not perfect, but decide whether the packet is a document or not + // by the existence of the lavc ttmlenc extradata. + ttml_ctx->input_type = (st->codecpar->extradata && + st->codecpar->extradata_size >= TTMLENC_EXTRADATA_SIGNATURE_SIZE && + !memcmp(st->codecpar->extradata, + TTMLENC_EXTRADATA_SIGNATURE, + TTMLENC_EXTRADATA_SIGNATURE_SIZE)) ? + PACKET_TYPE_PARAGRAPH : + PACKET_TYPE_DOCUMENT; + + avpriv_set_pts_info(st, 64, 1, 1000); + + if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) + avio_printf(pb, ttml_header_text, printed_lang); + } + + 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, " <p\n"); + ttml_write_time(pb, " begin", pkt->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, "</p>\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; +} + +AVOutputFormat ff_ttml_muxer = { + .name = "ttml", + .long_name = NULL_IF_CONFIG_SMALL("TTML subtitle"), + .extensions = "ttml", + .mime_type = "text/ttml", + .priv_data_size = sizeof(TTMLMuxContext), + .flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS | + AVFMT_TS_NONSTRICT, + .subtitle_codec = AV_CODEC_ID_TTML, + .write_header = ttml_write_header, + .write_packet = ttml_write_packet, + .write_trailer = ttml_write_trailer, +}; |