235 lines
7.5 KiB
C
235 lines
7.5 KiB
C
/*
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* 3GPP TS 26.245 Timed Text decoder
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* Copyright (c) 2012 Philip Langdale <philipl@overt.org>
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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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#include "avcodec.h"
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#include "ass.h"
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#include "libavutil/avstring.h"
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#include "libavutil/common.h"
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#include "libavutil/bprint.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/mem.h"
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#define STYLE_FLAG_BOLD (1<<0)
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#define STYLE_FLAG_ITALIC (1<<1)
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#define STYLE_FLAG_UNDERLINE (1<<2)
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typedef struct {
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uint16_t style_start;
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uint16_t style_end;
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uint8_t style_flag;
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} StyleBox;
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static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end,
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StyleBox **s, int style_entries)
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{
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int i = 0;
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int text_pos = 0;
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while (text < text_end) {
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for (i = 0; i < style_entries; i++) {
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if (s[i]->style_flag && text_pos == s[i]->style_end) {
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if (s[i]->style_flag & STYLE_FLAG_BOLD)
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av_bprintf(buf, "{\\b0}");
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if (s[i]->style_flag & STYLE_FLAG_ITALIC)
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av_bprintf(buf, "{\\i0}");
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if (s[i]->style_flag & STYLE_FLAG_UNDERLINE)
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av_bprintf(buf, "{\\u0}");
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}
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}
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for (i = 0; i < style_entries; i++) {
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if (s[i]->style_flag && text_pos == s[i]->style_start) {
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if (s[i]->style_flag & STYLE_FLAG_BOLD)
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av_bprintf(buf, "{\\b1}");
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if (s[i]->style_flag & STYLE_FLAG_ITALIC)
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av_bprintf(buf, "{\\i1}");
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if (s[i]->style_flag & STYLE_FLAG_UNDERLINE)
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av_bprintf(buf, "{\\u1}");
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}
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}
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switch (*text) {
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case '\r':
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break;
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case '\n':
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av_bprintf(buf, "\\N");
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break;
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default:
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av_bprint_chars(buf, *text, 1);
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break;
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}
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text++;
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text_pos++;
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}
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return 0;
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}
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static int mov_text_init(AVCodecContext *avctx) {
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/*
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* TODO: Handle the default text style.
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* NB: Most players ignore styles completely, with the result that
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* it's very common to find files where the default style is broken
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* and respecting it results in a worse experience than ignoring it.
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*/
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return ff_ass_subtitle_header_default(avctx);
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}
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static int mov_text_decode_frame(AVCodecContext *avctx,
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void *data, int *got_sub_ptr, AVPacket *avpkt)
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{
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AVSubtitle *sub = data;
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int ret, ts_start, ts_end;
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AVBPrint buf;
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char *ptr = avpkt->data;
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char *end;
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//char *ptr_temp;
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int text_length, tsmb_type, style_entries;
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uint64_t tsmb_size, tracksize;
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StyleBox **s = {0, };
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StyleBox *s_temp;
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const uint8_t *tsmb;
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int count, i, size_var;
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if (!ptr || avpkt->size < 2)
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return AVERROR_INVALIDDATA;
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/*
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* A packet of size two with value zero is an empty subtitle
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* used to mark the end of the previous non-empty subtitle.
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* We can just drop them here as we have duration information
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* already. If the value is non-zero, then it's technically a
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* bad packet.
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*/
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if (avpkt->size == 2)
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return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA;
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/*
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* The first two bytes of the packet are the length of the text string
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* In complex cases, there are style descriptors appended to the string
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* so we can't just assume the packet size is the string size.
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*/
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text_length = AV_RB16(ptr);
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end = ptr + FFMIN(2 + text_length, avpkt->size);
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ptr += 2;
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ts_start = av_rescale_q(avpkt->pts,
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avctx->time_base,
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(AVRational){1,100});
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ts_end = av_rescale_q(avpkt->pts + avpkt->duration,
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avctx->time_base,
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(AVRational){1,100});
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tsmb_size = 0;
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tracksize = 2 + text_length;
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// Note that the spec recommends lines be no longer than 2048 characters.
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av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
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if (text_length + 2 != avpkt->size) {
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while (tracksize + 8 <= avpkt->size) {
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// A box is a minimum of 8 bytes.
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tsmb = ptr + tracksize - 2;
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tsmb_size = AV_RB32(tsmb);
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tsmb += 4;
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tsmb_type = AV_RB32(tsmb);
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tsmb += 4;
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if (tsmb_size == 1) {
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if (tracksize + 16 > avpkt->size)
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break;
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tsmb_size = AV_RB64(tsmb);
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tsmb += 8;
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size_var = 18;
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} else
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size_var = 10;
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//size_var is equal to 10 or 18 depending on the size of box
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if (tracksize + tsmb_size > avpkt->size)
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break;
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if (tsmb_type == MKBETAG('s','t','y','l')) {
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if (tracksize + size_var > avpkt->size)
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break;
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style_entries = AV_RB16(tsmb);
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tsmb += 2;
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// A single style record is of length 12 bytes.
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if (tracksize + size_var + style_entries * 12 > avpkt->size)
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break;
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count = 0;
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for(i = 0; i < style_entries; i++) {
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s_temp = av_malloc(sizeof(*s_temp));
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if (!s_temp)
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goto error;
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s_temp->style_start = AV_RB16(tsmb);
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tsmb += 2;
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s_temp->style_end = AV_RB16(tsmb);
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tsmb += 2;
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// fontID = AV_RB16(tsmb);
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tsmb += 2;
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s_temp->style_flag = AV_RB8(tsmb);
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av_dynarray_add(&s, &count, s_temp);
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if(!s)
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goto error;
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//fontsize=AV_RB8(tsmb);
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tsmb += 2;
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// text-color-rgba
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tsmb += 4;
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}
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text_to_ass(&buf, ptr, end, s, style_entries);
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for(i = 0; i < count; i++) {
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av_freep(&s[i]);
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}
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av_freep(&s);
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}
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tracksize = tracksize + tsmb_size;
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}
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} else
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text_to_ass(&buf, ptr, end, NULL, 0);
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ret = ff_ass_add_rect_bprint(sub, &buf, ts_start, ts_end - ts_start);
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av_bprint_finalize(&buf, NULL);
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if (ret < 0)
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return ret;
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*got_sub_ptr = sub->num_rects > 0;
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return avpkt->size;
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error:
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for(i = 0; i < count; i++) {
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av_freep(&s[i]);
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}
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av_freep(&s);
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if (s_temp)
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av_freep(&s_temp);
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av_bprint_finalize(&buf, NULL);
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return AVERROR(ENOMEM);
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}
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AVCodec ff_movtext_decoder = {
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.name = "mov_text",
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.long_name = NULL_IF_CONFIG_SMALL("3GPP Timed Text subtitle"),
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.type = AVMEDIA_TYPE_SUBTITLE,
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.id = AV_CODEC_ID_MOV_TEXT,
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.init = mov_text_init,
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.decode = mov_text_decode_frame,
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};
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