yading@10: /*
yading@10:  * 3GPP TS 26.245 Timed Text decoder
yading@10:  * Copyright (c) 2012  Philip Langdale <philipl@overt.org>
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: #include "avcodec.h"
yading@10: #include "ass.h"
yading@10: #include "libavutil/avstring.h"
yading@10: #include "libavutil/common.h"
yading@10: #include "libavutil/bprint.h"
yading@10: #include "libavutil/intreadwrite.h"
yading@10: 
yading@10: static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end)
yading@10: {
yading@10:     while (text < text_end) {
yading@10:         switch (*text) {
yading@10:         case '\r':
yading@10:             break;
yading@10:         case '\n':
yading@10:             av_bprintf(buf, "\\N");
yading@10:             break;
yading@10:         default:
yading@10:             av_bprint_chars(buf, *text, 1);
yading@10:             break;
yading@10:         }
yading@10:         text++;
yading@10:     }
yading@10: 
yading@10:     av_bprintf(buf, "\r\n");
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int mov_text_init(AVCodecContext *avctx) {
yading@10:     /*
yading@10:      * TODO: Handle the default text style.
yading@10:      * NB: Most players ignore styles completely, with the result that
yading@10:      * it's very common to find files where the default style is broken
yading@10:      * and respecting it results in a worse experience than ignoring it.
yading@10:      */
yading@10:     return ff_ass_subtitle_header_default(avctx);
yading@10: }
yading@10: 
yading@10: static int mov_text_decode_frame(AVCodecContext *avctx,
yading@10:                             void *data, int *got_sub_ptr, AVPacket *avpkt)
yading@10: {
yading@10:     AVSubtitle *sub = data;
yading@10:     int ts_start, ts_end;
yading@10:     AVBPrint buf;
yading@10:     const char *ptr = avpkt->data;
yading@10:     const char *end;
yading@10: 
yading@10:     if (!ptr || avpkt->size < 2)
yading@10:         return AVERROR_INVALIDDATA;
yading@10: 
yading@10:     /*
yading@10:      * A packet of size two with value zero is an empty subtitle
yading@10:      * used to mark the end of the previous non-empty subtitle.
yading@10:      * We can just drop them here as we have duration information
yading@10:      * already. If the value is non-zero, then it's technically a
yading@10:      * bad packet.
yading@10:      */
yading@10:     if (avpkt->size == 2)
yading@10:         return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA;
yading@10: 
yading@10:     /*
yading@10:      * The first two bytes of the packet are the length of the text string
yading@10:      * In complex cases, there are style descriptors appended to the string
yading@10:      * so we can't just assume the packet size is the string size.
yading@10:      */
yading@10:     end = ptr + FFMIN(2 + AV_RB16(ptr), avpkt->size);
yading@10:     ptr += 2;
yading@10: 
yading@10:     ts_start = av_rescale_q(avpkt->pts,
yading@10:                             avctx->time_base,
yading@10:                             (AVRational){1,100});
yading@10:     ts_end   = av_rescale_q(avpkt->pts + avpkt->duration,
yading@10:                             avctx->time_base,
yading@10:                             (AVRational){1,100});
yading@10: 
yading@10:     // Note that the spec recommends lines be no longer than 2048 characters.
yading@10:     av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
yading@10:     text_to_ass(&buf, ptr, end);
yading@10: 
yading@10:     if (!av_bprint_is_complete(&buf))
yading@10:         return AVERROR(ENOMEM);
yading@10: 
yading@10:     ff_ass_add_rect(sub, buf.str, ts_start, ts_end-ts_start, 0);
yading@10:     *got_sub_ptr = sub->num_rects > 0;
yading@10:     av_bprint_finalize(&buf, NULL);
yading@10:     return avpkt->size;
yading@10: }
yading@10: 
yading@10: AVCodec ff_movtext_decoder = {
yading@10:     .name         = "mov_text",
yading@10:     .long_name    = NULL_IF_CONFIG_SMALL("3GPP Timed Text subtitle"),
yading@10:     .type         = AVMEDIA_TYPE_SUBTITLE,
yading@10:     .id           = AV_CODEC_ID_MOV_TEXT,
yading@10:     .init         = mov_text_init,
yading@10:     .decode       = mov_text_decode_frame,
yading@10: };