FFmpeg: libavcodec/srtenc.c Source File

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libavcodec

srtenc.c

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1 /*

2 * SubRip subtitle encoder

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 */

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"

30 #define SRT_STACK_SIZE 64

32 typedef struct {

33 AVCodecContext *avctx;

34 ASSSplitContext *ass_ctx;

35 AVBPrint buffer;

36 unsigned timestamp_end;

37 int count;

38 char stack[SRT_STACK_SIZE];

39 int stack_ptr;

40 int alignment_applied;

41 } SRTContext;

44 #ifdef __GNUC__

45 __attribute__ ((__format__ (__printf__, 2, 3)))

46 #endif

47 static void srt_print(SRTContext *s, const char *str, ...)

48 {

49 va_list vargs;

50 va_start(vargs, str);

51 av_vbprintf(&s->buffer, str, vargs);

52 va_end(vargs);

53 }

55 static int srt_stack_push(SRTContext *s, const char c)

56 {

57 if (s->stack_ptr >= SRT_STACK_SIZE)

58 return -1;

59 s->stack[s->stack_ptr++] = c;

60 return 0;

61 }

63 static char srt_stack_pop(SRTContext *s)

64 {

65 if (s->stack_ptr <= 0)

66 return 0;

67 return s->stack[--s->stack_ptr];

68 }

70 static int srt_stack_find(SRTContext *s, const char c)

71 {

72 int i;

73 for (i = s->stack_ptr-1; i >= 0; i--)

74 if (s->stack[i] == c)

75 break;

76 return i;

77 }

79 static void srt_close_tag(SRTContext *s, char tag)

80 {

81 srt_print(s, "</%c%s>", tag, tag == 'f' ? "ont" : "");

82 }

84 static void srt_stack_push_pop(SRTContext *s, const char c, int close)

85 {

86 if (close) {

87 int i = c ? srt_stack_find(s, c) : 0;

88 if (i < 0)

89 return;

90 while (s->stack_ptr != i)

91 srt_close_tag(s, srt_stack_pop(s));

92 } else if (srt_stack_push(s, c) < 0)

93 av_log(s->avctx, AV_LOG_ERROR, "tag stack overflow\n");

94 }

96 static void srt_style_apply(SRTContext *s, const char *style)

97 {

98 ASSStyle *st = ff_ass_style_get(s->ass_ctx, style);

99 if (st) {

100 int c = st->primary_color & 0xFFFFFF;

101 if (st->font_name && strcmp(st->font_name, ASS_DEFAULT_FONT) ||

102 st->font_size != ASS_DEFAULT_FONT_SIZE ||

103 c != ASS_DEFAULT_COLOR) {

104 srt_print(s, "<font");

105 if (st->font_name && strcmp(st->font_name, ASS_DEFAULT_FONT))

106 srt_print(s, " face=\"%s\"", st->font_name);

107 if (st->font_size != ASS_DEFAULT_FONT_SIZE)

108 srt_print(s, " size=\"%d\"", st->font_size);

109 if (c != ASS_DEFAULT_COLOR)

110 srt_print(s, " color=\"#%06x\"",

111 (c & 0xFF0000) >> 16 | c & 0xFF00 | (c & 0xFF) << 16);

112 srt_print(s, ">");

113 srt_stack_push(s, 'f');

114 }

115 if (st->bold != ASS_DEFAULT_BOLD) {

116 srt_print(s, "");

117 srt_stack_push(s, 'b');

118 }

119 if (st->italic != ASS_DEFAULT_ITALIC) {

120 srt_print(s, "");

121 srt_stack_push(s, 'i');

122 }

123 if (st->underline != ASS_DEFAULT_UNDERLINE) {

124 srt_print(s, "");

125 srt_stack_push(s, 'u');

126 }

127 if (st->alignment != ASS_DEFAULT_ALIGNMENT) {

128 srt_print(s, "{\\an%d}", st->alignment);

129 s->alignment_applied = 1;

130 }

131 }

132 }

133

134

135 static av_cold int srt_encode_init(AVCodecContext *avctx)

136 {

137 SRTContext *s = avctx->priv_data;

138 s->avctx = avctx;

139 s->ass_ctx = ff_ass_split(avctx->subtitle_header);

140 av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);

141 return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;

142 }

143

144 static void srt_text_cb(void *priv, const char *text, int len)

145 {

146 SRTContext *s = priv;

147 av_bprint_append_data(&s->buffer, text, len);

148 }

149

150 static void srt_new_line_cb(void *priv, int forced)

151 {

152 srt_print(priv, "\r\n");

153 }

154

155 static void srt_style_cb(void *priv, char style, int close)

156 {

157 srt_stack_push_pop(priv, style, close);

158 if (!close)

159 srt_print(priv, "<%c>", style);

160 }

161

162 static void srt_color_cb(void *priv, unsigned int color, unsigned int color_id)

163 {

164 if (color_id > 1)

165 return;

166 srt_stack_push_pop(priv, 'f', color == 0xFFFFFFFF);

167 if (color != 0xFFFFFFFF)

168 srt_print(priv, "",

169 (color & 0xFF0000) >> 16 | color & 0xFF00 | (color & 0xFF) << 16);

170 }

171

172 static void srt_font_name_cb(void *priv, const char *name)

173 {

174 srt_stack_push_pop(priv, 'f', !name);

175 if (name)

176 srt_print(priv, "", name);

177 }

178

179 static void srt_font_size_cb(void *priv, int size)

180 {

181 srt_stack_push_pop(priv, 'f', size < 0);

182 if (size >= 0)

183 srt_print(priv, "", size);

184 }

185

186 static void srt_alignment_cb(void *priv, int alignment)

187 {

188 SRTContext *s = priv;

189 if (!s->alignment_applied && alignment >= 0) {

190 srt_print(s, "{\\an%d}", alignment);

191 s->alignment_applied = 1;

192 }

193 }

194

195 static void srt_cancel_overrides_cb(void *priv, const char *style)

196 {

197 srt_stack_push_pop(priv, 0, 1);

198 srt_style_apply(priv, style);

199 }

200

201 static void srt_move_cb(void *priv, int x1, int y1, int x2, int y2,

202 int t1, int t2)

203 {

204 SRTContext *s = priv;

205

206 if (s->avctx->codec->id == AV_CODEC_ID_SRT) {

207 char buffer[32];

208 int len = snprintf(buffer, sizeof(buffer),

209 " X1:%03u X2:%03u Y1:%03u Y2:%03u", x1, x2, y1, y2);

210 unsigned char *dummy;

211 unsigned room;

212

213 av_bprint_get_buffer(&s->buffer, len, &dummy, &room);

214 if (room >= len) {

215 memmove(s->buffer.str + s->timestamp_end + len,

216 s->buffer.str + s->timestamp_end,

217 s->buffer.len - s->timestamp_end + 1);

218 memcpy(s->buffer.str + s->timestamp_end, buffer, len);

219 }

220 /* Increment even if av_bprint_get_buffer() did not return enough room:

221 the bprint structure will be treated as truncated. */

222 s->buffer.len += len;

223 }

224 }

225

226 static void srt_end_cb(void *priv)

227 {

228 SRTContext *s = priv;

229

230 srt_stack_push_pop(priv, 0, 1);

231 if (s->avctx->codec->id == AV_CODEC_ID_SRT)

232 srt_print(priv, "\r\n\r\n");

233 }

234

235 static const ASSCodesCallbacks srt_callbacks = {

236 .text = srt_text_cb,

237 .new_line = srt_new_line_cb,

238 .style = srt_style_cb,

239 .color = srt_color_cb,

240 .font_name = srt_font_name_cb,

241 .font_size = srt_font_size_cb,

242 .alignment = srt_alignment_cb,

243 .cancel_overrides = srt_cancel_overrides_cb,

244 .move = srt_move_cb,

245 .end = srt_end_cb,

246 };

247

248 static int srt_encode_frame(AVCodecContext *avctx,

249 unsigned char *buf, int bufsize, const AVSubtitle *sub)

250 {

251 SRTContext *s = avctx->priv_data;

252 ASSDialog *dialog;

253 int i, num;

254

255 av_bprint_clear(&s->buffer);

256

257 for (i=0; i<sub->num_rects; i++) {

258

259 if (sub->rects[i]->type != SUBTITLE_ASS) {

260 av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");

261 return AVERROR(ENOSYS);

262 }

263

264 dialog = ff_ass_split_dialog(s->ass_ctx, sub->rects[i]->ass, 0, &num);

265 for (; dialog && num--; dialog++) {

266 if (avctx->codec->id == AV_CODEC_ID_SRT) {

267 int sh, sm, ss, sc = 10 * dialog->start;

268 int eh, em, es, ec = 10 * dialog->end;

269 sh = sc/3600000; sc -= 3600000*sh;

270 sm = sc/ 60000; sc -= 60000*sm;

271 ss = sc/ 1000; sc -= 1000*ss;

272 eh = ec/3600000; ec -= 3600000*eh;

273 em = ec/ 60000; ec -= 60000*em;

274 es = ec/ 1000; ec -= 1000*es;

275 srt_print(s,"%d\r\n%02d:%02d:%02d,%03d --> %02d:%02d:%02d,%03d\r\n",

276 ++s->count, sh, sm, ss, sc, eh, em, es, ec);

277 s->timestamp_end = s->buffer.len - 2;

278 }

279 s->alignment_applied = 0;

280 srt_style_apply(s, dialog->style);

281 ff_ass_split_override_codes(&srt_callbacks, s, dialog->text);

282 }

283 }

284

285 if (!av_bprint_is_complete(&s->buffer))

286 return AVERROR(ENOMEM);

287 if (!s->buffer.len)

288 return 0;

289

290 if (s->buffer.len > bufsize) {

291 av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");

292 return -1;

293 }

294 memcpy(buf, s->buffer.str, s->buffer.len);

295

296 return s->buffer.len;

297 }

298

299 static int srt_encode_close(AVCodecContext *avctx)

300 {

301 SRTContext *s = avctx->priv_data;

302 ff_ass_split_free(s->ass_ctx);

303 av_bprint_finalize(&s->buffer, NULL);

304 return 0;

305 }

306

307 #if CONFIG_SRT_ENCODER

308 /* deprecated encoder */

309 AVCodec ff_srt_encoder = {

310 .name = "srt",

311 .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle with embedded timing"),

312 .type = AVMEDIA_TYPE_SUBTITLE,

313 .id = AV_CODEC_ID_SRT,

314 .priv_data_size = sizeof(SRTContext),

315 .init = srt_encode_init,

316 .encode_sub = srt_encode_frame,

317 .close = srt_encode_close,

318 };

319 #endif

320

321 #if CONFIG_SUBRIP_ENCODER

322 AVCodec ff_subrip_encoder = {

323 .name = "subrip",

324 .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),

325 .type = AVMEDIA_TYPE_SUBTITLE,

326 .id = AV_CODEC_ID_SUBRIP,

327 .priv_data_size = sizeof(SRTContext),

328 .init = srt_encode_init,

329 .encode_sub = srt_encode_frame,

330 .close = srt_encode_close,

331 };

332 #endif

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