FFmpeg
srtenc.c
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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 "config_components.h"
23 
24 #include <stdarg.h>
25 #include "avcodec.h"
26 #include "libavutil/bprint.h"
27 #include "ass_split.h"
28 #include "ass.h"
29 #include "codec_internal.h"
30 
31 
32 #define SRT_STACK_SIZE 64
33 
34 typedef struct {
37  AVBPrint buffer;
38  char stack[SRT_STACK_SIZE];
39  int stack_ptr;
41 } SRTContext;
42 
43 
44 static av_printf_format(2, 3) void srt_print(SRTContext *s, const char *str, ...)
45 {
46  va_list vargs;
47  va_start(vargs, str);
48  av_vbprintf(&s->buffer, str, vargs);
49  va_end(vargs);
50 }
51 
52 static int srt_stack_push(SRTContext *s, const char c)
53 {
54  if (s->stack_ptr >= SRT_STACK_SIZE)
55  return -1;
56  s->stack[s->stack_ptr++] = c;
57  return 0;
58 }
59 
60 static char srt_stack_pop(SRTContext *s)
61 {
62  if (s->stack_ptr <= 0)
63  return 0;
64  return s->stack[--s->stack_ptr];
65 }
66 
67 static int srt_stack_find(SRTContext *s, const char c)
68 {
69  int i;
70  for (i = s->stack_ptr-1; i >= 0; i--)
71  if (s->stack[i] == c)
72  break;
73  return i;
74 }
75 
76 static void srt_close_tag(SRTContext *s, char tag)
77 {
78  srt_print(s, "</%c%s>", tag, tag == 'f' ? "ont" : "");
79 }
80 
81 static void srt_stack_push_pop(SRTContext *s, const char c, int close)
82 {
83  if (close) {
84  int i = c ? srt_stack_find(s, c) : 0;
85  if (i < 0)
86  return;
87  while (s->stack_ptr != i)
89  } else if (srt_stack_push(s, c) < 0)
90  av_log(s->avctx, AV_LOG_ERROR, "tag stack overflow\n");
91 }
92 
93 static void srt_style_apply(SRTContext *s, const char *style)
94 {
95  ASSStyle *st = ff_ass_style_get(s->ass_ctx, style);
96  if (st) {
97  int c = st->primary_color & 0xFFFFFF;
98  if (st->font_name && strcmp(st->font_name, ASS_DEFAULT_FONT) ||
100  c != ASS_DEFAULT_COLOR) {
101  srt_print(s, "<font");
102  if (st->font_name && strcmp(st->font_name, ASS_DEFAULT_FONT))
103  srt_print(s, " face=\"%s\"", st->font_name);
104  if (st->font_size != ASS_DEFAULT_FONT_SIZE)
105  srt_print(s, " size=\"%d\"", st->font_size);
106  if (c != ASS_DEFAULT_COLOR)
107  srt_print(s, " color=\"#%06x\"",
108  (c & 0xFF0000) >> 16 | c & 0xFF00 | (c & 0xFF) << 16);
109  srt_print(s, ">");
110  srt_stack_push(s, 'f');
111  }
112  if (st->bold != ASS_DEFAULT_BOLD) {
113  srt_print(s, "<b>");
114  srt_stack_push(s, 'b');
115  }
116  if (st->italic != ASS_DEFAULT_ITALIC) {
117  srt_print(s, "<i>");
118  srt_stack_push(s, 'i');
119  }
120  if (st->underline != ASS_DEFAULT_UNDERLINE) {
121  srt_print(s, "<u>");
122  srt_stack_push(s, 'u');
123  }
124  if (st->alignment != ASS_DEFAULT_ALIGNMENT) {
125  srt_print(s, "{\\an%d}", st->alignment);
126  s->alignment_applied = 1;
127  }
128  }
129 }
130 
131 
133 {
134  SRTContext *s = avctx->priv_data;
135  s->avctx = avctx;
136  s->ass_ctx = ff_ass_split(avctx->subtitle_header);
137  return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
138 }
139 
140 static void srt_text_cb(void *priv, const char *text, int len)
141 {
142  SRTContext *s = priv;
143  av_bprint_append_data(&s->buffer, text, len);
144 }
145 
146 static void srt_new_line_cb(void *priv, int forced)
147 {
148  srt_print(priv, "\r\n");
149 }
150 
151 static void srt_style_cb(void *priv, char style, int close)
152 {
153  srt_stack_push_pop(priv, style, close);
154  if (!close)
155  srt_print(priv, "<%c>", style);
156 }
157 
158 static void srt_color_cb(void *priv, unsigned int color, unsigned int color_id)
159 {
160  if (color_id > 1)
161  return;
162  srt_stack_push_pop(priv, 'f', color == 0xFFFFFFFF);
163  if (color != 0xFFFFFFFF)
164  srt_print(priv, "<font color=\"#%06x\">",
165  (color & 0xFF0000) >> 16 | color & 0xFF00 | (color & 0xFF) << 16);
166 }
167 
168 static void srt_font_name_cb(void *priv, const char *name)
169 {
170  srt_stack_push_pop(priv, 'f', !name);
171  if (name)
172  srt_print(priv, "<font face=\"%s\">", name);
173 }
174 
175 static void srt_font_size_cb(void *priv, int size)
176 {
177  srt_stack_push_pop(priv, 'f', size < 0);
178  if (size >= 0)
179  srt_print(priv, "<font size=\"%d\">", size);
180 }
181 
182 static void srt_alignment_cb(void *priv, int alignment)
183 {
184  SRTContext *s = priv;
185  if (!s->alignment_applied && alignment >= 0) {
186  srt_print(s, "{\\an%d}", alignment);
187  s->alignment_applied = 1;
188  }
189 }
190 
191 static void srt_cancel_overrides_cb(void *priv, const char *style)
192 {
193  srt_stack_push_pop(priv, 0, 1);
194  srt_style_apply(priv, style);
195 }
196 
197 static void srt_move_cb(void *priv, int x1, int y1, int x2, int y2,
198  int t1, int t2)
199 {
200  // TODO: add a AV_PKT_DATA_SUBTITLE_POSITION side data when a new subtitles
201  // encoding API passing the AVPacket is available.
202 }
203 
204 static void srt_end_cb(void *priv)
205 {
206  srt_stack_push_pop(priv, 0, 1);
207 }
208 
210  .text = srt_text_cb,
211  .new_line = srt_new_line_cb,
212  .style = srt_style_cb,
213  .color = srt_color_cb,
214  .font_name = srt_font_name_cb,
215  .font_size = srt_font_size_cb,
216  .alignment = srt_alignment_cb,
217  .cancel_overrides = srt_cancel_overrides_cb,
218  .move = srt_move_cb,
219  .end = srt_end_cb,
220 };
221 
223  .text = srt_text_cb,
224  .new_line = srt_new_line_cb,
225 };
226 
227 static int encode_frame(AVCodecContext *avctx,
228  unsigned char *buf, int bufsize, const AVSubtitle *sub,
229  const ASSCodesCallbacks *cb)
230 {
231  SRTContext *s = avctx->priv_data;
232  ASSDialog *dialog;
233  int i;
234 
235  av_bprint_init_for_buffer(&s->buffer, buf, bufsize);
236 
237  for (i=0; i<sub->num_rects; i++) {
238  const char *ass = sub->rects[i]->ass;
239 
240  if (sub->rects[i]->type != SUBTITLE_ASS) {
241  av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
242  return AVERROR(EINVAL);
243  }
244 
245  dialog = ff_ass_split_dialog(s->ass_ctx, ass);
246  if (!dialog)
247  return AVERROR(ENOMEM);
248  s->alignment_applied = 0;
249  if (avctx->codec_id == AV_CODEC_ID_SUBRIP)
250  srt_style_apply(s, dialog->style);
252  ff_ass_free_dialog(&dialog);
253  }
254 
255  if (!s->buffer.len)
256  return 0;
257 
258  if (!av_bprint_is_complete(&s->buffer)) {
259  av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
261  }
262 
263  return s->buffer.len;
264 }
265 
267  unsigned char *buf, int bufsize, const AVSubtitle *sub)
268 {
269  return encode_frame(avctx, buf, bufsize, sub, &srt_callbacks);
270 }
271 
273  unsigned char *buf, int bufsize, const AVSubtitle *sub)
274 {
275  return encode_frame(avctx, buf, bufsize, sub, &text_callbacks);
276 }
277 
279 {
280  SRTContext *s = avctx->priv_data;
281  ff_ass_split_free(s->ass_ctx);
282  return 0;
283 }
284 
285 #if CONFIG_SRT_ENCODER
286 /* deprecated encoder */
287 const FFCodec ff_srt_encoder = {
288  .p.name = "srt",
289  CODEC_LONG_NAME("SubRip subtitle"),
290  .p.type = AVMEDIA_TYPE_SUBTITLE,
291  .p.id = AV_CODEC_ID_SUBRIP,
292  .priv_data_size = sizeof(SRTContext),
295  .close = srt_encode_close,
296 };
297 #endif
298 
299 #if CONFIG_SUBRIP_ENCODER
300 const FFCodec ff_subrip_encoder = {
301  .p.name = "subrip",
302  CODEC_LONG_NAME("SubRip subtitle"),
303  .p.type = AVMEDIA_TYPE_SUBTITLE,
304  .p.id = AV_CODEC_ID_SUBRIP,
305  .priv_data_size = sizeof(SRTContext),
308  .close = srt_encode_close,
309 };
310 #endif
311 
312 #if CONFIG_TEXT_ENCODER
313 const FFCodec ff_text_encoder = {
314  .p.name = "text",
315  CODEC_LONG_NAME("Raw text subtitle"),
316  .p.type = AVMEDIA_TYPE_SUBTITLE,
317  .p.id = AV_CODEC_ID_TEXT,
318  .priv_data_size = sizeof(SRTContext),
321  .close = srt_encode_close,
322 };
323 #endif
srt_new_line_cb
static void srt_new_line_cb(void *priv, int forced)
Definition: srtenc.c:146
AVSubtitle
Definition: avcodec.h:2227
AVMEDIA_TYPE_SUBTITLE
@ AVMEDIA_TYPE_SUBTITLE
Definition: avutil.h:204
name
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf default minimum maximum flags name is the option name
Definition: writing_filters.txt:88
srt_stack_find
static int srt_stack_find(SRTContext *s, const char c)
Definition: srtenc.c:67
ASSCodesCallbacks
Set of callback functions corresponding to each override codes that can be encountered in a "Dialogue...
Definition: ass_split.h:138
av_bprint_is_complete
static int av_bprint_is_complete(const AVBPrint *buf)
Test if the print buffer is complete (not truncated).
Definition: bprint.h:218
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
AVSubtitle::rects
AVSubtitleRect ** rects
Definition: avcodec.h:2232
srt_stack_push_pop
static void srt_stack_push_pop(SRTContext *s, const char c, int close)
Definition: srtenc.c:81
color
Definition: vf_paletteuse.c:512
cb
static double cb(void *priv, double x, double y)
Definition: vf_geq.c:242
text_callbacks
static const ASSCodesCallbacks text_callbacks
Definition: srtenc.c:222
ASSStyle::alignment
int alignment
position of the text (left, center, top...), defined after the layout of the numpad (1-3 sub,...
Definition: ass_split.h:58
SRT_STACK_SIZE
#define SRT_STACK_SIZE
Definition: srtenc.c:32
srt_alignment_cb
static void srt_alignment_cb(void *priv, int alignment)
Definition: srtenc.c:182
AVSubtitle::num_rects
unsigned num_rects
Definition: avcodec.h:2231
SRTContext
Definition: srtenc.c:34
ff_ass_split_dialog
ASSDialog * ff_ass_split_dialog(ASSSplitContext *ctx, const char *buf)
Split one ASS Dialogue line from a string buffer.
Definition: ass_split.c:433
ASS_DEFAULT_ALIGNMENT
#define ASS_DEFAULT_ALIGNMENT
Definition: ass.h:42
ASSStyle::font_size
int font_size
font height
Definition: ass_split.h:42
FFCodec
Definition: codec_internal.h:127
AVCodecContext::subtitle_header
uint8_t * subtitle_header
Definition: avcodec.h:1891
t1
#define t1
Definition: regdef.h:29
srt_encode_init
static av_cold int srt_encode_init(AVCodecContext *avctx)
Definition: srtenc.c:132
ASSDialog::style
char * style
name of the ASSStyle to use with this dialog
Definition: ass_split.h:76
SUBTITLE_ASS
@ SUBTITLE_ASS
Formatted text, the ass field must be set by the decoder and is authoritative.
Definition: avcodec.h:2195
srt_encode_frame
static int srt_encode_frame(AVCodecContext *avctx, unsigned char *buf, int bufsize, const AVSubtitle *sub)
Definition: srtenc.c:266
ASSStyle::font_name
char * font_name
font face (case sensitive)
Definition: ass_split.h:41
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:131
av_bprint_init_for_buffer
void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size)
Init a print buffer using a pre-existing buffer.
Definition: bprint.c:85
ass_split.h
ff_srt_encoder
const FFCodec ff_srt_encoder
AVERROR_BUFFER_TOO_SMALL
#define AVERROR_BUFFER_TOO_SMALL
Buffer too small.
Definition: error.h:53
AVSubtitleRect::ass
char * ass
0 terminated ASS/SSA compatible event line.
Definition: avcodec.h:2224
srt_stack_pop
static char srt_stack_pop(SRTContext *s)
Definition: srtenc.c:60
ass.h
ff_ass_free_dialog
void ff_ass_free_dialog(ASSDialog **dialogp)
Free a dialogue obtained from ff_ass_split_dialog().
Definition: ass_split.c:421
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
ASS_DEFAULT_FONT
#define ASS_DEFAULT_FONT
Definition: ass.h:35
av_cold
#define av_cold
Definition: attributes.h:90
SRTContext::alignment_applied
int alignment_applied
Definition: srtenc.c:40
s
#define s(width, name)
Definition: cbs_vp9.c:198
ff_text_encoder
const FFCodec ff_text_encoder
SRTContext::stack_ptr
int stack_ptr
Definition: srtenc.c:39
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:272
srt_font_size_cb
static void srt_font_size_cb(void *priv, int size)
Definition: srtenc.c:175
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:455
ASSStyle::primary_color
int primary_color
color that a subtitle will normally appear in
Definition: ass_split.h:43
srt_stack_push
static int srt_stack_push(SRTContext *s, const char c)
Definition: srtenc.c:52
srt_encode_close
static int srt_encode_close(AVCodecContext *avctx)
Definition: srtenc.c:278
FF_CODEC_ENCODE_SUB_CB
#define FF_CODEC_ENCODE_SUB_CB(func)
Definition: codec_internal.h:299
ASSSplitContext
This struct can be casted to ASS to access to the split data.
Definition: ass_split.c:205
ff_ass_split
ASSSplitContext * ff_ass_split(const char *buf)
Split a full ASS file or a ASS header from a string buffer and store the split structure in a newly a...
Definition: ass_split.c:382
srt_cancel_overrides_cb
static void srt_cancel_overrides_cb(void *priv, const char *style)
Definition: srtenc.c:191
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
ASSStyle
fields extracted from the [V4(+) Styles] section
Definition: ass_split.h:39
srt_close_tag
static void srt_close_tag(SRTContext *s, char tag)
Definition: srtenc.c:76
ASSStyle::underline
int underline
whether text is underlined (1) or not (0)
Definition: ass_split.h:49
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts.c:366
ff_ass_split_free
void ff_ass_split_free(ASSSplitContext *ctx)
Free all the memory allocated for an ASSSplitContext.
Definition: ass_split.c:470
ASS_DEFAULT_BOLD
#define ASS_DEFAULT_BOLD
Definition: ass.h:39
SRTContext::avctx
AVCodecContext * avctx
Definition: srtenc.c:35
codec_internal.h
ASSDialog::text
char * text
actual text which will be displayed as a subtitle, can include style override control codes (see ff_a...
Definition: ass_split.h:82
SRTContext::ass_ctx
ASSSplitContext * ass_ctx
Definition: srtenc.c:36
size
int size
Definition: twinvq_data.h:10344
srt_move_cb
static void srt_move_cb(void *priv, int x1, int y1, int x2, int y2, int t1, int t2)
Definition: srtenc.c:197
ASSStyle::italic
int italic
whether text is italic (1) or not (0)
Definition: ass_split.h:48
AVSubtitleRect::type
enum AVSubtitleType type
Definition: avcodec.h:2215
av_printf_format
static av_printf_format(2, 3)
Definition: srtenc.c:44
encode_frame
static int encode_frame(AVCodecContext *avctx, unsigned char *buf, int bufsize, const AVSubtitle *sub, const ASSCodesCallbacks *cb)
Definition: srtenc.c:227
srt_color_cb
static void srt_color_cb(void *priv, unsigned int color, unsigned int color_id)
Definition: srtenc.c:158
ASS_DEFAULT_UNDERLINE
#define ASS_DEFAULT_UNDERLINE
Definition: ass.h:41
ff_ass_style_get
ASSStyle * ff_ass_style_get(ASSSplitContext *ctx, const char *style)
Find an ASSStyle structure by its name.
Definition: ass_split.c:578
bprint.h
srt_style_apply
static void srt_style_apply(SRTContext *s, const char *style)
Definition: srtenc.c:93
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
AV_CODEC_ID_SUBRIP
@ AV_CODEC_ID_SUBRIP
Definition: codec_id.h:567
ff_subrip_encoder
const FFCodec ff_subrip_encoder
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:194
ASS_DEFAULT_ITALIC
#define ASS_DEFAULT_ITALIC
Definition: ass.h:40
len
int len
Definition: vorbis_enc_data.h:426
ASS_DEFAULT_COLOR
#define ASS_DEFAULT_COLOR
Definition: ass.h:37
avcodec.h
tag
uint32_t tag
Definition: movenc.c:1787
SRTContext::buffer
AVBPrint buffer
Definition: srtenc.c:37
AV_CODEC_ID_TEXT
@ AV_CODEC_ID_TEXT
raw UTF-8 text
Definition: codec_id.h:552
srt_end_cb
static void srt_end_cb(void *priv)
Definition: srtenc.c:204
ASS_DEFAULT_FONT_SIZE
#define ASS_DEFAULT_FONT_SIZE
Definition: ass.h:36
AVCodecContext
main external API structure.
Definition: avcodec.h:445
t2
#define t2
Definition: regdef.h:30
av_vbprintf
void av_vbprintf(AVBPrint *buf, const char *fmt, va_list vl_arg)
Append a formatted string to a print buffer.
Definition: bprint.c:122
srt_style_cb
static void srt_style_cb(void *priv, char style, int close)
Definition: srtenc.c:151
ASSDialog
fields extracted from the [Events] section
Definition: ass_split.h:71
srt_text_cb
static void srt_text_cb(void *priv, const char *text, int len)
Definition: srtenc.c:140
srt_font_name_cb
static void srt_font_name_cb(void *priv, const char *name)
Definition: srtenc.c:168
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:472
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
ff_ass_split_override_codes
int ff_ass_split_override_codes(const ASSCodesCallbacks *callbacks, void *priv, const char *buf)
Split override codes out of a ASS "Dialogue" Text field.
Definition: ass_split.c:483
srt_callbacks
static const ASSCodesCallbacks srt_callbacks
Definition: srtenc.c:209
av_bprint_append_data
void av_bprint_append_data(AVBPrint *buf, const char *data, unsigned size)
Append data to a print buffer.
Definition: bprint.c:163
text_encode_frame
static int text_encode_frame(AVCodecContext *avctx, unsigned char *buf, int bufsize, const AVSubtitle *sub)
Definition: srtenc.c:272
ASSStyle::bold
int bold
whether text is bold (1) or not (0)
Definition: ass_split.h:47
ASSCodesCallbacks::text
void(* text)(void *priv, const char *text, int len)
Definition: ass_split.h:143