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  1. /*
  2.  * SSA/ASS encoder
  3.  * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  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.
  11.  *
  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.
  16.  *
  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
  20.  */
  21.  
  22. #include <string.h>
  23.  
  24. #include "avcodec.h"
  25. #include "ass_split.h"
  26. #include "ass.h"
  27. #include "libavutil/avstring.h"
  28. #include "libavutil/internal.h"
  29. #include "libavutil/mem.h"
  30.  
  31. typedef struct {
  32.     int id; ///< current event id, ReadOrder field
  33. } ASSEncodeContext;
  34.  
  35. static av_cold int ass_encode_init(AVCodecContext *avctx)
  36. {
  37.     avctx->extradata = av_malloc(avctx->subtitle_header_size + 1);
  38.     if (!avctx->extradata)
  39.         return AVERROR(ENOMEM);
  40.     memcpy(avctx->extradata, avctx->subtitle_header, avctx->subtitle_header_size);
  41.     avctx->extradata_size = avctx->subtitle_header_size;
  42.     avctx->extradata[avctx->extradata_size] = 0;
  43.     return 0;
  44. }
  45.  
  46. static int ass_encode_frame(AVCodecContext *avctx,
  47.                             unsigned char *buf, int bufsize,
  48.                             const AVSubtitle *sub)
  49. {
  50.     ASSEncodeContext *s = avctx->priv_data;
  51.     int i, len, total_len = 0;
  52.  
  53.     for (i=0; i<sub->num_rects; i++) {
  54.         char ass_line[2048];
  55.         const char *ass = sub->rects[i]->ass;
  56.  
  57.         if (sub->rects[i]->type != SUBTITLE_ASS) {
  58.             av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
  59.             return -1;
  60.         }
  61.  
  62.         if (strncmp(ass, "Dialogue: ", 10)) {
  63.             av_log(avctx, AV_LOG_ERROR, "AVSubtitle rectangle ass \"%s\""
  64.                    " does not look like a SSA markup\n", ass);
  65.             return AVERROR_INVALIDDATA;
  66.         }
  67.  
  68.         if (avctx->codec->id == AV_CODEC_ID_ASS) {
  69.             long int layer;
  70.             char *p;
  71.  
  72.             if (i > 0) {
  73.                 av_log(avctx, AV_LOG_ERROR, "ASS encoder supports only one "
  74.                        "ASS rectangle field.\n");
  75.                 return AVERROR_INVALIDDATA;
  76.             }
  77.  
  78.             ass += 10; // skip "Dialogue: "
  79.             /* parse Layer field. If it's a Marked field, the content
  80.              * will be "Marked=N" instead of the layer num, so we will
  81.              * have layer=0, which is fine. */
  82.             layer = strtol(ass, &p, 10);
  83.  
  84. #define SKIP_ENTRY(ptr) do {        \
  85.     char *sep = strchr(ptr, ',');   \
  86.     if (sep)                        \
  87.         ptr = sep + 1;              \
  88. } while (0)
  89.  
  90.             SKIP_ENTRY(p); // skip layer or marked
  91.             SKIP_ENTRY(p); // skip start timestamp
  92.             SKIP_ENTRY(p); // skip end timestamp
  93.             snprintf(ass_line, sizeof(ass_line), "%d,%ld,%s", ++s->id, layer, p);
  94.             ass_line[strcspn(ass_line, "\r\n")] = 0;
  95.             ass = ass_line;
  96.         }
  97.         len = av_strlcpy(buf+total_len, ass, bufsize-total_len);
  98.  
  99.         if (len > bufsize-total_len-1) {
  100.             av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
  101.             return -1;
  102.         }
  103.  
  104.         total_len += len;
  105.     }
  106.  
  107.     return total_len;
  108. }
  109.  
  110. #if CONFIG_SSA_ENCODER
  111. AVCodec ff_ssa_encoder = {
  112.     .name         = "ssa",
  113.     .long_name    = NULL_IF_CONFIG_SMALL("SSA (SubStation Alpha) subtitle"),
  114.     .type         = AVMEDIA_TYPE_SUBTITLE,
  115.     .id           = AV_CODEC_ID_SSA,
  116.     .init         = ass_encode_init,
  117.     .encode_sub   = ass_encode_frame,
  118.     .priv_data_size = sizeof(ASSEncodeContext),
  119. };
  120. #endif
  121.  
  122. #if CONFIG_ASS_ENCODER
  123. AVCodec ff_ass_encoder = {
  124.     .name         = "ass",
  125.     .long_name    = NULL_IF_CONFIG_SMALL("ASS (Advanced SubStation Alpha) subtitle"),
  126.     .type         = AVMEDIA_TYPE_SUBTITLE,
  127.     .id           = AV_CODEC_ID_ASS,
  128.     .init         = ass_encode_init,
  129.     .encode_sub   = ass_encode_frame,
  130.     .priv_data_size = sizeof(ASSEncodeContext),
  131. };
  132. #endif
  133.