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  1. /*
  2.  * SubRip subtitle 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 <stdarg.h>
  23. #include "avcodec.h"
  24. #include "libavutil/avstring.h"
  25. #include "libavutil/bprint.h"
  26. #include "ass_split.h"
  27. #include "ass.h"
  28.  
  29.  
  30. #define SRT_STACK_SIZE 64
  31.  
  32. typedef struct {
  33.     AVCodecContext *avctx;
  34.     ASSSplitContext *ass_ctx;
  35.     AVBPrint buffer;
  36.     char stack[SRT_STACK_SIZE];
  37.     int stack_ptr;
  38.     int alignment_applied;
  39. } SRTContext;
  40.  
  41.  
  42. #ifdef __GNUC__
  43. __attribute__ ((__format__ (__printf__, 2, 3)))
  44. #endif
  45. static void srt_print(SRTContext *s, const char *str, ...)
  46. {
  47.     va_list vargs;
  48.     va_start(vargs, str);
  49.     av_vbprintf(&s->buffer, str, vargs);
  50.     va_end(vargs);
  51. }
  52.  
  53. static int srt_stack_push(SRTContext *s, const char c)
  54. {
  55.     if (s->stack_ptr >= SRT_STACK_SIZE)
  56.         return -1;
  57.     s->stack[s->stack_ptr++] = c;
  58.     return 0;
  59. }
  60.  
  61. static char srt_stack_pop(SRTContext *s)
  62. {
  63.     if (s->stack_ptr <= 0)
  64.         return 0;
  65.     return s->stack[--s->stack_ptr];
  66. }
  67.  
  68. static int srt_stack_find(SRTContext *s, const char c)
  69. {
  70.     int i;
  71.     for (i = s->stack_ptr-1; i >= 0; i--)
  72.         if (s->stack[i] == c)
  73.             break;
  74.     return i;
  75. }
  76.  
  77. static void srt_close_tag(SRTContext *s, char tag)
  78. {
  79.     srt_print(s, "</%c%s>", tag, tag == 'f' ? "ont" : "");
  80. }
  81.  
  82. static void srt_stack_push_pop(SRTContext *s, const char c, int close)
  83. {
  84.     if (close) {
  85.         int i = c ? srt_stack_find(s, c) : 0;
  86.         if (i < 0)
  87.             return;
  88.         while (s->stack_ptr != i)
  89.             srt_close_tag(s, srt_stack_pop(s));
  90.     } else if (srt_stack_push(s, c) < 0)
  91.         av_log(s->avctx, AV_LOG_ERROR, "tag stack overflow\n");
  92. }
  93.  
  94. static void srt_style_apply(SRTContext *s, const char *style)
  95. {
  96.     ASSStyle *st = ff_ass_style_get(s->ass_ctx, style);
  97.     if (st) {
  98.         int c = st->primary_color & 0xFFFFFF;
  99.         if (st->font_name && strcmp(st->font_name, ASS_DEFAULT_FONT) ||
  100.             st->font_size != ASS_DEFAULT_FONT_SIZE ||
  101.             c != ASS_DEFAULT_COLOR) {
  102.             srt_print(s, "<font");
  103.             if (st->font_name && strcmp(st->font_name, ASS_DEFAULT_FONT))
  104.                 srt_print(s, " face=\"%s\"", st->font_name);
  105.             if (st->font_size != ASS_DEFAULT_FONT_SIZE)
  106.                 srt_print(s, " size=\"%d\"", st->font_size);
  107.             if (c != ASS_DEFAULT_COLOR)
  108.                 srt_print(s, " color=\"#%06x\"",
  109.                           (c & 0xFF0000) >> 16 | c & 0xFF00 | (c & 0xFF) << 16);
  110.             srt_print(s, ">");
  111.             srt_stack_push(s, 'f');
  112.         }
  113.         if (st->bold != ASS_DEFAULT_BOLD) {
  114.             srt_print(s, "<b>");
  115.             srt_stack_push(s, 'b');
  116.         }
  117.         if (st->italic != ASS_DEFAULT_ITALIC) {
  118.             srt_print(s, "<i>");
  119.             srt_stack_push(s, 'i');
  120.         }
  121.         if (st->underline != ASS_DEFAULT_UNDERLINE) {
  122.             srt_print(s, "<u>");
  123.             srt_stack_push(s, 'u');
  124.         }
  125.         if (st->alignment != ASS_DEFAULT_ALIGNMENT) {
  126.             srt_print(s, "{\\an%d}", st->alignment);
  127.             s->alignment_applied = 1;
  128.         }
  129.     }
  130. }
  131.  
  132.  
  133. static av_cold int srt_encode_init(AVCodecContext *avctx)
  134. {
  135.     SRTContext *s = avctx->priv_data;
  136.     s->avctx = avctx;
  137.     s->ass_ctx = ff_ass_split(avctx->subtitle_header);
  138.     av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
  139.     return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
  140. }
  141.  
  142. static void srt_text_cb(void *priv, const char *text, int len)
  143. {
  144.     SRTContext *s = priv;
  145.     av_bprint_append_data(&s->buffer, text, len);
  146. }
  147.  
  148. static void srt_new_line_cb(void *priv, int forced)
  149. {
  150.     srt_print(priv, "\r\n");
  151. }
  152.  
  153. static void srt_style_cb(void *priv, char style, int close)
  154. {
  155.     srt_stack_push_pop(priv, style, close);
  156.     if (!close)
  157.         srt_print(priv, "<%c>", style);
  158. }
  159.  
  160. static void srt_color_cb(void *priv, unsigned int color, unsigned int color_id)
  161. {
  162.     if (color_id > 1)
  163.         return;
  164.     srt_stack_push_pop(priv, 'f', color == 0xFFFFFFFF);
  165.     if (color != 0xFFFFFFFF)
  166.         srt_print(priv, "<font color=\"#%06x\">",
  167.               (color & 0xFF0000) >> 16 | color & 0xFF00 | (color & 0xFF) << 16);
  168. }
  169.  
  170. static void srt_font_name_cb(void *priv, const char *name)
  171. {
  172.     srt_stack_push_pop(priv, 'f', !name);
  173.     if (name)
  174.         srt_print(priv, "<font face=\"%s\">", name);
  175. }
  176.  
  177. static void srt_font_size_cb(void *priv, int size)
  178. {
  179.     srt_stack_push_pop(priv, 'f', size < 0);
  180.     if (size >= 0)
  181.         srt_print(priv, "<font size=\"%d\">", size);
  182. }
  183.  
  184. static void srt_alignment_cb(void *priv, int alignment)
  185. {
  186.     SRTContext *s = priv;
  187.     if (!s->alignment_applied && alignment >= 0) {
  188.         srt_print(s, "{\\an%d}", alignment);
  189.         s->alignment_applied = 1;
  190.     }
  191. }
  192.  
  193. static void srt_cancel_overrides_cb(void *priv, const char *style)
  194. {
  195.     srt_stack_push_pop(priv, 0, 1);
  196.     srt_style_apply(priv, style);
  197. }
  198.  
  199. static void srt_move_cb(void *priv, int x1, int y1, int x2, int y2,
  200.                         int t1, int t2)
  201. {
  202.     // TODO: add a AV_PKT_DATA_SUBTITLE_POSITION side data when a new subtitles
  203.     // encoding API passing the AVPacket is available.
  204. }
  205.  
  206. static void srt_end_cb(void *priv)
  207. {
  208.     srt_stack_push_pop(priv, 0, 1);
  209. }
  210.  
  211. static const ASSCodesCallbacks srt_callbacks = {
  212.     .text             = srt_text_cb,
  213.     .new_line         = srt_new_line_cb,
  214.     .style            = srt_style_cb,
  215.     .color            = srt_color_cb,
  216.     .font_name        = srt_font_name_cb,
  217.     .font_size        = srt_font_size_cb,
  218.     .alignment        = srt_alignment_cb,
  219.     .cancel_overrides = srt_cancel_overrides_cb,
  220.     .move             = srt_move_cb,
  221.     .end              = srt_end_cb,
  222. };
  223.  
  224. static int srt_encode_frame(AVCodecContext *avctx,
  225.                             unsigned char *buf, int bufsize, const AVSubtitle *sub)
  226. {
  227.     SRTContext *s = avctx->priv_data;
  228.     ASSDialog *dialog;
  229.     int i, num;
  230.  
  231.     av_bprint_clear(&s->buffer);
  232.  
  233.     for (i=0; i<sub->num_rects; i++) {
  234.  
  235.         if (sub->rects[i]->type != SUBTITLE_ASS) {
  236.             av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
  237.             return AVERROR(ENOSYS);
  238.         }
  239.  
  240.         dialog = ff_ass_split_dialog(s->ass_ctx, sub->rects[i]->ass, 0, &num);
  241.         for (; dialog && num--; dialog++) {
  242.             s->alignment_applied = 0;
  243.             srt_style_apply(s, dialog->style);
  244.             ff_ass_split_override_codes(&srt_callbacks, s, dialog->text);
  245.         }
  246.     }
  247.  
  248.     if (!av_bprint_is_complete(&s->buffer))
  249.         return AVERROR(ENOMEM);
  250.     if (!s->buffer.len)
  251.         return 0;
  252.  
  253.     if (s->buffer.len > bufsize) {
  254.         av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
  255.         return -1;
  256.     }
  257.     memcpy(buf, s->buffer.str, s->buffer.len);
  258.  
  259.     return s->buffer.len;
  260. }
  261.  
  262. static int srt_encode_close(AVCodecContext *avctx)
  263. {
  264.     SRTContext *s = avctx->priv_data;
  265.     ff_ass_split_free(s->ass_ctx);
  266.     av_bprint_finalize(&s->buffer, NULL);
  267.     return 0;
  268. }
  269.  
  270. #if CONFIG_SRT_ENCODER
  271. /* deprecated encoder */
  272. AVCodec ff_srt_encoder = {
  273.     .name           = "srt",
  274.     .long_name      = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
  275.     .type           = AVMEDIA_TYPE_SUBTITLE,
  276.     .id             = AV_CODEC_ID_SUBRIP,
  277.     .priv_data_size = sizeof(SRTContext),
  278.     .init           = srt_encode_init,
  279.     .encode_sub     = srt_encode_frame,
  280.     .close          = srt_encode_close,
  281. };
  282. #endif
  283.  
  284. #if CONFIG_SUBRIP_ENCODER
  285. AVCodec ff_subrip_encoder = {
  286.     .name           = "subrip",
  287.     .long_name      = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
  288.     .type           = AVMEDIA_TYPE_SUBTITLE,
  289.     .id             = AV_CODEC_ID_SUBRIP,
  290.     .priv_data_size = sizeof(SRTContext),
  291.     .init           = srt_encode_init,
  292.     .encode_sub     = srt_encode_frame,
  293.     .close          = srt_encode_close,
  294. };
  295. #endif
  296.