libavformat/ttmlenc.c - manifest_repos/ffmpeg - Git at Google

 /*
  * 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,
 };
	/*
	* 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,
	};