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234 lines
7.3 KiB
234 lines
7.3 KiB
/* |
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* TTML subtitle muxer |
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* Copyright (c) 2020 24i |
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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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/** |
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* @file |
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* TTML subtitle muxer |
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* @see https://www.w3.org/TR/ttml1/ |
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* @see https://www.w3.org/TR/ttml2/ |
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* @see https://www.w3.org/TR/ttml-imsc/rec |
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*/ |
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#include "avformat.h" |
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#include "internal.h" |
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#include "libavcodec/ttmlenc.h" |
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#include "libavutil/internal.h" |
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enum TTMLPacketType { |
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PACKET_TYPE_PARAGRAPH, |
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PACKET_TYPE_DOCUMENT, |
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}; |
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struct TTMLHeaderParameters { |
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const char *tt_element_params; |
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const char *pre_body_elements; |
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}; |
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typedef struct TTMLMuxContext { |
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enum TTMLPacketType input_type; |
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unsigned int document_written; |
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} TTMLMuxContext; |
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static const char ttml_header_text[] = |
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"<?xml version=\"1.0\" encoding=\"utf-8\"?>\n" |
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"<tt\n" |
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"%s" |
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" xml:lang=\"%s\">\n" |
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"%s" |
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" <body>\n" |
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" <div>\n"; |
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static const char ttml_footer_text[] = |
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" </div>\n" |
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" </body>\n" |
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"</tt>\n"; |
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static void ttml_write_time(AVIOContext *pb, const char tag[], |
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int64_t millisec) |
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{ |
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int64_t sec, min, hour; |
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sec = millisec / 1000; |
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millisec -= 1000 * sec; |
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min = sec / 60; |
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sec -= 60 * min; |
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hour = min / 60; |
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min -= 60 * hour; |
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avio_printf(pb, "%s=\"%02"PRId64":%02"PRId64":%02"PRId64".%03"PRId64"\"", |
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tag, hour, min, sec, millisec); |
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} |
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static int ttml_set_header_values_from_extradata( |
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AVCodecParameters *par, struct TTMLHeaderParameters *header_params) |
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{ |
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size_t additional_data_size = |
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par->extradata_size - TTMLENC_EXTRADATA_SIGNATURE_SIZE; |
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char *value = |
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(char *)par->extradata + TTMLENC_EXTRADATA_SIGNATURE_SIZE; |
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size_t value_size = av_strnlen(value, additional_data_size); |
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struct TTMLHeaderParameters local_params = { 0 }; |
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if (!additional_data_size) { |
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// simple case, we don't have to go through local_params and just |
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// set default fall-back values (for old extradata format). |
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header_params->tt_element_params = ttml_default_namespacing; |
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header_params->pre_body_elements = ""; |
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return 0; |
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} |
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if (value_size == additional_data_size || |
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value[value_size] != '\0') |
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return AVERROR_INVALIDDATA; |
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local_params.tt_element_params = value; |
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additional_data_size -= value_size + 1; |
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value += value_size + 1; |
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if (!additional_data_size) |
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return AVERROR_INVALIDDATA; |
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value_size = av_strnlen(value, additional_data_size); |
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if (value_size == additional_data_size || |
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value[value_size] != '\0') |
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return AVERROR_INVALIDDATA; |
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local_params.pre_body_elements = value; |
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*header_params = local_params; |
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return 0; |
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} |
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static int ttml_write_header(AVFormatContext *ctx) |
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{ |
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TTMLMuxContext *ttml_ctx = ctx->priv_data; |
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ttml_ctx->document_written = 0; |
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if (ctx->nb_streams != 1 || |
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ctx->streams[0]->codecpar->codec_id != AV_CODEC_ID_TTML) { |
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av_log(ctx, AV_LOG_ERROR, "Exactly one TTML stream is required!\n"); |
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return AVERROR(EINVAL); |
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} |
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{ |
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AVStream *st = ctx->streams[0]; |
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AVIOContext *pb = ctx->pb; |
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AVDictionaryEntry *lang = av_dict_get(st->metadata, "language", NULL, |
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0); |
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const char *printed_lang = (lang && lang->value) ? lang->value : ""; |
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// Not perfect, but decide whether the packet is a document or not |
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// by the existence of the lavc ttmlenc extradata. |
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ttml_ctx->input_type = (st->codecpar->extradata && |
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st->codecpar->extradata_size >= TTMLENC_EXTRADATA_SIGNATURE_SIZE && |
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!memcmp(st->codecpar->extradata, |
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TTMLENC_EXTRADATA_SIGNATURE, |
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TTMLENC_EXTRADATA_SIGNATURE_SIZE)) ? |
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PACKET_TYPE_PARAGRAPH : |
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PACKET_TYPE_DOCUMENT; |
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avpriv_set_pts_info(st, 64, 1, 1000); |
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if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) { |
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struct TTMLHeaderParameters header_params; |
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int ret = ttml_set_header_values_from_extradata( |
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st->codecpar, &header_params); |
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if (ret < 0) { |
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av_log(ctx, AV_LOG_ERROR, |
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"Failed to parse TTML header values from extradata: " |
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"%s!\n", av_err2str(ret)); |
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return ret; |
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} |
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avio_printf(pb, ttml_header_text, |
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header_params.tt_element_params, |
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printed_lang, |
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header_params.pre_body_elements); |
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} |
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} |
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return 0; |
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} |
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static int ttml_write_packet(AVFormatContext *ctx, AVPacket *pkt) |
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{ |
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TTMLMuxContext *ttml_ctx = ctx->priv_data; |
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AVIOContext *pb = ctx->pb; |
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switch (ttml_ctx->input_type) { |
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case PACKET_TYPE_PARAGRAPH: |
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// write out a paragraph element with the given contents. |
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avio_printf(pb, " <p\n"); |
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ttml_write_time(pb, " begin", pkt->pts); |
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avio_w8(pb, '\n'); |
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ttml_write_time(pb, " end", pkt->pts + pkt->duration); |
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avio_printf(pb, ">"); |
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avio_write(pb, pkt->data, pkt->size); |
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avio_printf(pb, "</p>\n"); |
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break; |
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case PACKET_TYPE_DOCUMENT: |
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// dump the given document out as-is. |
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if (ttml_ctx->document_written) { |
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av_log(ctx, AV_LOG_ERROR, |
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"Attempting to write multiple TTML documents into a " |
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"single document! The XML specification forbids this " |
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"as there has to be a single root tag.\n"); |
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return AVERROR(EINVAL); |
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} |
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avio_write(pb, pkt->data, pkt->size); |
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ttml_ctx->document_written = 1; |
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break; |
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default: |
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av_log(ctx, AV_LOG_ERROR, |
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"Internal error: invalid TTML input packet type: %d!\n", |
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ttml_ctx->input_type); |
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return AVERROR_BUG; |
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} |
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return 0; |
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} |
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static int ttml_write_trailer(AVFormatContext *ctx) |
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{ |
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TTMLMuxContext *ttml_ctx = ctx->priv_data; |
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AVIOContext *pb = ctx->pb; |
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if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) |
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avio_printf(pb, ttml_footer_text); |
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return 0; |
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} |
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const AVOutputFormat ff_ttml_muxer = { |
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.name = "ttml", |
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.long_name = NULL_IF_CONFIG_SMALL("TTML subtitle"), |
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.extensions = "ttml", |
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.mime_type = "text/ttml", |
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.priv_data_size = sizeof(TTMLMuxContext), |
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.flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS | |
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AVFMT_TS_NONSTRICT, |
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.subtitle_codec = AV_CODEC_ID_TTML, |
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.write_header = ttml_write_header, |
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.write_packet = ttml_write_packet, |
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.write_trailer = ttml_write_trailer, |
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};
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