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ffmpeg / libavcodec / srtdec.c @ 2912e87a

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/*
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 * SubRip subtitle decoder
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 * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
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 *
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 * This file is part of Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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 "libavutil/avstring.h"
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#include "libavutil/parseutils.h"
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#include "avcodec.h"
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#include "ass.h"
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static int html_color_parse(AVCodecContext *avctx, const char *str)
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{
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    uint8_t rgba[4];
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    if (av_parse_color(rgba, str, strcspn(str, "\" >"), avctx) < 0)
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        return -1;
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    return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
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}
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enum {
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    PARAM_UNKNOWN = -1,
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    PARAM_SIZE,
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    PARAM_COLOR,
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    PARAM_FACE,
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    PARAM_NUMBER
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};
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typedef struct {
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    char tag[128];
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    char param[PARAM_NUMBER][128];
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} SrtStack;
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static const char *srt_to_ass(AVCodecContext *avctx, char *out, char *out_end,
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                              const char *in, int x1, int y1, int x2, int y2)
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{
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    char c, *param, buffer[128], tmp[128];
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    int len, tag_close, sptr = 1, line_start = 1, an = 0, end = 0;
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    SrtStack stack[16];
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    stack[0].tag[0] = 0;
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    strcpy(stack[0].param[PARAM_SIZE],  "{\\fs}");
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    strcpy(stack[0].param[PARAM_COLOR], "{\\c}");
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    strcpy(stack[0].param[PARAM_FACE],  "{\\fn}");
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    if (x1 >= 0 && y1 >= 0) {
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        if (x2 >= 0 && y2 >= 0 && (x2 != x1 || y2 != y1))
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            out += snprintf(out, out_end-out,
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                            "{\\an1}{\\move(%d,%d,%d,%d)}", x1, y1, x2, y2);
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        else
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            out += snprintf(out, out_end-out, "{\\an1}{\\pos(%d,%d)}", x1, y1);
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    }
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    for (; out < out_end && !end && *in; in++) {
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        switch (*in) {
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        case '\r':
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            break;
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        case '\n':
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            if (line_start) {
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                end = 1;
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                break;
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            }
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            while (out[-1] == ' ')
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                out--;
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            out += snprintf(out, out_end-out, "\\N");
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            line_start = 1;
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            break;
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        case ' ':
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            if (!line_start)
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                *out++ = *in;
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            break;
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        case '{':    /* skip all {\xxx} substrings except for {\an%d}
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                        and all microdvd like styles such as {Y:xxx} */
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            an += sscanf(in, "{\\an%*1u}%c", &c) == 1;
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            if ((an != 1 && sscanf(in, "{\\%*[^}]}%n%c", &len, &c) > 0) ||
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                sscanf(in, "{%*1[CcFfoPSsYy]:%*[^}]}%n%c", &len, &c) > 0) {
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                in += len - 1;
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            } else
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                *out++ = *in;
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            break;
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        case '<':
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            tag_close = in[1] == '/';
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            if (sscanf(in+tag_close+1, "%128[^>]>%n%c", buffer, &len,&c) >= 2) {
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                if ((param = strchr(buffer, ' ')))
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                    *param++ = 0;
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                if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack)) ||
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                    ( tag_close && sptr > 0 && !strcmp(stack[sptr-1].tag, buffer))) {
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                    int i, j, unknown = 0;
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                    in += len + tag_close;
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                    if (!tag_close)
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                        memset(stack+sptr, 0, sizeof(*stack));
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                    if (!strcmp(buffer, "font")) {
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                        if (tag_close) {
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                            for (i=PARAM_NUMBER-1; i>=0; i--)
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                                if (stack[sptr-1].param[i][0])
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                                    for (j=sptr-2; j>=0; j--)
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                                        if (stack[j].param[i][0]) {
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                                            out += snprintf(out, out_end-out,
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                                                            stack[j].param[i]);
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                                            break;
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                                        }
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                        } else {
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                            while (param) {
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                                if (!strncmp(param, "size=", 5)) {
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                                    unsigned font_size;
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                                    param += 5 + (param[5] == '"');
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                                    if (sscanf(param, "%u", &font_size) == 1) {
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                                        snprintf(stack[sptr].param[PARAM_SIZE],
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                                             sizeof(stack[0].param[PARAM_SIZE]),
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                                             "{\\fs%u}", font_size);
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                                    }
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                                } else if (!strncmp(param, "color=", 6)) {
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                                    param += 6 + (param[6] == '"');
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                                    snprintf(stack[sptr].param[PARAM_COLOR],
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                                         sizeof(stack[0].param[PARAM_COLOR]),
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                                         "{\\c&H%X&}",
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                                         html_color_parse(avctx, param));
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                                } else if (!strncmp(param, "face=", 5)) {
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                                    param += 5 + (param[5] == '"');
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                                    len = strcspn(param,
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                                                  param[-1] == '"' ? "\"" :" ");
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                                    av_strlcpy(tmp, param,
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                                               FFMIN(sizeof(tmp), len+1));
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                                    param += len;
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                                    snprintf(stack[sptr].param[PARAM_FACE],
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                                             sizeof(stack[0].param[PARAM_FACE]),
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                                             "{\\fn%s}", tmp);
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                                }
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                                if ((param = strchr(param, ' ')))
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                                    param++;
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                            }
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                            for (i=0; i<PARAM_NUMBER; i++)
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                                if (stack[sptr].param[i][0])
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                                    out += snprintf(out, out_end-out,
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                                                    stack[sptr].param[i]);
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                        }
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                    } else if (!buffer[1] && strspn(buffer, "bisu") == 1) {
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                        out += snprintf(out, out_end-out,
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                                        "{\\%c%d}", buffer[0], !tag_close);
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                    } else {
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                        unknown = 1;
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                        snprintf(tmp, sizeof(tmp), "</%s>", buffer);
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                    }
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                    if (tag_close) {
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                        sptr--;
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                    } else if (unknown && !strstr(in, tmp)) {
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                        in -= len + tag_close;
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                        *out++ = *in;
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                    } else
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                        av_strlcpy(stack[sptr++].tag, buffer,
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                                   sizeof(stack[0].tag));
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                    break;
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                }
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            }
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        default:
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            *out++ = *in;
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            break;
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        }
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        if (*in != ' ' && *in != '\r' && *in != '\n')
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            line_start = 0;
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    }
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    out = FFMIN(out, out_end-3);
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    while (!strncmp(out-2, "\\N", 2))
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        out -= 2;
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    while (out[-1] == ' ')
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        out--;
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    out += snprintf(out, out_end-out, "\r\n");
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    return in;
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}
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static const char *read_ts(const char *buf, int *ts_start, int *ts_end,
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                           int *x1, int *y1, int *x2, int *y2)
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{
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    int i, hs, ms, ss, he, me, se;
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    for (i=0; i<2; i++) {
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        /* try to read timestamps in either the first or second line */
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        int c = sscanf(buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
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                       "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
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                       &hs, &ms, &ss, ts_start, &he, &me, &se, ts_end,
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                       x1, x2, y1, y2);
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        buf += strcspn(buf, "\n") + 1;
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        if (c >= 8) {
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            *ts_start = 100*(ss + 60*(ms + 60*hs)) + *ts_start/10;
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            *ts_end   = 100*(se + 60*(me + 60*he)) + *ts_end  /10;
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            return buf;
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        }
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    }
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    return NULL;
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}
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static int srt_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 ts_start, ts_end, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
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    char buffer[2048];
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    const char *ptr = avpkt->data;
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    const char *end = avpkt->data + avpkt->size;
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    if (avpkt->size <= 0)
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        return avpkt->size;
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    ff_ass_init(sub);
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    while (ptr < end && *ptr) {
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        ptr = read_ts(ptr, &ts_start, &ts_end, &x1, &y1, &x2, &y2);
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        if (!ptr)
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            break;
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        ptr = srt_to_ass(avctx, buffer, buffer+sizeof(buffer), ptr,
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                         x1, y1, x2, y2);
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        ff_ass_add_rect(sub, buffer, ts_start, ts_end, 0);
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    }
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    *got_sub_ptr = sub->num_rects > 0;
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    return avpkt->size;
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}
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AVCodec ff_srt_decoder = {
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    .name         = "srt",
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    .long_name    = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
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    .type         = AVMEDIA_TYPE_SUBTITLE,
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    .id           = CODEC_ID_SRT,
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    .init         = ff_ass_subtitle_header_default,
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    .decode       = srt_decode_frame,
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};