2 * 3GPP TS 26.245 Timed Text decoder
3 * Copyright (c) 2012 Philip Langdale <philipl@overt.org>
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 #include "libavutil/avstring.h"
25 #include "libavutil/common.h"
26 #include "libavutil/bprint.h"
27 #include "libavutil/intreadwrite.h"
29 static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end)
31 while (text < text_end) {
36 av_bprintf(buf, "\\N");
39 av_bprint_chars(buf, *text, 1);
45 av_bprintf(buf, "\r\n");
49 static int mov_text_init(AVCodecContext *avctx) {
51 * TODO: Handle the default text style.
52 * NB: Most players ignore styles completely, with the result that
53 * it's very common to find files where the default style is broken
54 * and respecting it results in a worse experience than ignoring it.
56 return ff_ass_subtitle_header_default(avctx);
59 static int mov_text_decode_frame(AVCodecContext *avctx,
60 void *data, int *got_sub_ptr, AVPacket *avpkt)
62 AVSubtitle *sub = data;
65 const char *ptr = avpkt->data;
68 if (!ptr || avpkt->size <= 2)
69 return avpkt->size ? AVERROR_INVALIDDATA : 0;
72 * The first two bytes of the packet are the length of the text string
73 * In complex cases, there are style descriptors appended to the string
74 * so we can't just assume the packet size is the string size.
76 end = ptr + FFMAX(2 + AV_RB16(ptr), avpkt->size);
79 ts_start = av_rescale_q(avpkt->pts,
82 ts_end = av_rescale_q(avpkt->pts + avpkt->duration,
86 // Note that the spec recommends lines be no longer than 2048 characters.
87 av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
88 text_to_ass(&buf, ptr, end);
90 if (!av_bprint_is_complete(&buf))
91 return AVERROR(ENOMEM);
93 ff_ass_add_rect(sub, buf.str, ts_start, ts_end-ts_start, 0);
94 *got_sub_ptr = sub->num_rects > 0;
95 av_bprint_finalize(&buf, NULL);
99 AVCodec ff_movtext_decoder = {
101 .long_name = NULL_IF_CONFIG_SMALL("3GPP Timed Text subtitle"),
102 .type = AVMEDIA_TYPE_SUBTITLE,
103 .id = AV_CODEC_ID_MOV_TEXT,
104 .init = mov_text_init,
105 .decode = mov_text_decode_frame,