FFmpeg
assenc.c
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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.h"
26 #include "libavutil/avstring.h"
27 #include "libavutil/internal.h"
28 #include "libavutil/mem.h"
29 
30 typedef struct {
31  int id; ///< current event id, ReadOrder field
33 
35 {
36  avctx->extradata = av_malloc(avctx->subtitle_header_size + 1);
37  if (!avctx->extradata)
38  return AVERROR(ENOMEM);
39  memcpy(avctx->extradata, avctx->subtitle_header, avctx->subtitle_header_size);
40  avctx->extradata_size = avctx->subtitle_header_size;
41  avctx->extradata[avctx->extradata_size] = 0;
42  return 0;
43 }
44 
45 static int ass_encode_frame(AVCodecContext *avctx,
46  unsigned char *buf, int bufsize,
47  const AVSubtitle *sub)
48 {
49  ASSEncodeContext *s = avctx->priv_data;
50  int i, len, total_len = 0;
51 
52  for (i=0; i<sub->num_rects; i++) {
53  char ass_line[2048];
54  const char *ass = sub->rects[i]->ass;
55  long int layer;
56  char *p;
57 
58  if (sub->rects[i]->type != SUBTITLE_ASS) {
59  av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
60  return AVERROR(EINVAL);
61  }
62 
63 #if FF_API_ASS_TIMING
64  if (!strncmp(ass, "Dialogue: ", 10)) {
65  if (i > 0) {
66  av_log(avctx, AV_LOG_ERROR, "ASS encoder supports only one "
67  "ASS rectangle field.\n");
68  return AVERROR_INVALIDDATA;
69  }
70 
71  ass += 10; // skip "Dialogue: "
72  /* parse Layer field. If it's a Marked field, the content
73  * will be "Marked=N" instead of the layer num, so we will
74  * have layer=0, which is fine. */
75  layer = strtol(ass, &p, 10);
76 
77 #define SKIP_ENTRY(ptr) do { \
78  char *sep = strchr(ptr, ','); \
79  if (sep) \
80  ptr = sep + 1; \
81 } while (0)
82 
83  SKIP_ENTRY(p); // skip layer or marked
84  SKIP_ENTRY(p); // skip start timestamp
85  SKIP_ENTRY(p); // skip end timestamp
86  snprintf(ass_line, sizeof(ass_line), "%d,%ld,%s", ++s->id, layer, p);
87  ass_line[strcspn(ass_line, "\r\n")] = 0;
88  ass = ass_line;
89  }
90 #endif
91 
92  len = av_strlcpy(buf+total_len, ass, bufsize-total_len);
93 
94  if (len > bufsize-total_len-1) {
95  av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
96  return AVERROR(EINVAL);
97  }
98 
99  total_len += len;
100  }
101 
102  return total_len;
103 }
104 
105 #if CONFIG_SSA_ENCODER
107  .name = "ssa",
108  .long_name = NULL_IF_CONFIG_SMALL("ASS (Advanced SubStation Alpha) subtitle"),
109  .type = AVMEDIA_TYPE_SUBTITLE,
110  .id = AV_CODEC_ID_ASS,
111  .init = ass_encode_init,
112  .encode_sub = ass_encode_frame,
113  .priv_data_size = sizeof(ASSEncodeContext),
114 };
115 #endif
116 
117 #if CONFIG_ASS_ENCODER
119  .name = "ass",
120  .long_name = NULL_IF_CONFIG_SMALL("ASS (Advanced SubStation Alpha) subtitle"),
121  .type = AVMEDIA_TYPE_SUBTITLE,
122  .id = AV_CODEC_ID_ASS,
123  .init = ass_encode_init,
124  .encode_sub = ass_encode_frame,
125  .priv_data_size = sizeof(ASSEncodeContext),
126 };
127 #endif
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
Memory handling functions.
static int ass_encode_frame(AVCodecContext *avctx, unsigned char *buf, int bufsize, const AVSubtitle *sub)
Definition: assenc.c:45
unsigned num_rects
Definition: avcodec.h:3924
AVCodec.
Definition: avcodec.h:3468
AVSubtitleRect ** rects
Definition: avcodec.h:3925
#define av_cold
Definition: attributes.h:82
#define av_malloc(s)
int subtitle_header_size
Definition: avcodec.h:3038
uint8_t * extradata
some codecs need / can use extradata like Huffman tables.
Definition: avcodec.h:1657
static av_cold int ass_encode_init(AVCodecContext *avctx)
Definition: assenc.c:34
#define av_log(a,...)
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
const char * name
Name of the codec implementation.
Definition: avcodec.h:3475
size_t av_strlcpy(char *dst, const char *src, size_t size)
Copy the string src to dst, but no more than size - 1 bytes, and null-terminate dst.
Definition: avstring.c:83
common internal API header
#define s(width, name)
Definition: cbs_vp9.c:257
#define SKIP_ENTRY(ptr)
Libavcodec external API header.
AVCodec ff_ssa_encoder
main external API structure.
Definition: avcodec.h:1556
void * buf
Definition: avisynth_c.h:690
int extradata_size
Definition: avcodec.h:1658
#define snprintf
Definition: snprintf.h:34
AVCodec ff_ass_encoder
void * priv_data
Definition: avcodec.h:1583
Formatted text, the ass field must be set by the decoder and is authoritative.
Definition: avcodec.h:3880
int len
char * ass
0 terminated ASS/SSA compatible event line.
Definition: avcodec.h:3915
int id
current event id, ReadOrder field
Definition: assenc.c:31
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
enum AVSubtitleType type
Definition: avcodec.h:3906
uint8_t * subtitle_header
Header containing style information for text subtitles.
Definition: avcodec.h:3037