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xsubdec.c
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1 /*
2  * XSUB subtitle decoder
3  * Copyright (c) 2007 Reimar Döffinger
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 "libavutil/mathematics.h"
23 #include "libavutil/imgutils.h"
24 #include "avcodec.h"
25 #include "get_bits.h"
26 #include "bytestream.h"
27 
28 static av_cold int decode_init(AVCodecContext *avctx) {
29  avctx->pix_fmt = AV_PIX_FMT_PAL8;
30  return 0;
31 }
32 
33 static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 };
34 static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 };
35 
36 static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {
37  int i;
38  int64_t ms = 0;
39  if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.')
40  return AV_NOPTS_VALUE;
41  for (i = 0; i < sizeof(tc_offsets); i++) {
42  uint8_t c = buf[tc_offsets[i]] - '0';
43  if (c > 9) return AV_NOPTS_VALUE;
44  ms = (ms + c) * tc_muls[i];
45  }
46  return ms - packet_time;
47 }
48 
49 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
50  AVPacket *avpkt) {
51  const uint8_t *buf = avpkt->data;
52  int buf_size = avpkt->size;
53  AVSubtitle *sub = data;
54  const uint8_t *buf_end = buf + buf_size;
55  uint8_t *bitmap;
56  int w, h, x, y, i;
57  int64_t packet_time = 0;
58  GetBitContext gb;
59  int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A');
60 
61  // check that at least header fits
62  if (buf_size < 27 + 7 * 2 + 4 * (3 + has_alpha)) {
63  av_log(avctx, AV_LOG_ERROR, "coded frame size %d too small\n", buf_size);
64  return -1;
65  }
66 
67  // read start and end time
68  if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') {
69  av_log(avctx, AV_LOG_ERROR, "invalid time code\n");
70  return -1;
71  }
72  if (avpkt->pts != AV_NOPTS_VALUE)
73  packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000});
74  sub->start_display_time = parse_timecode(buf + 1, packet_time);
75  sub->end_display_time = parse_timecode(buf + 14, packet_time);
76  buf += 27;
77 
78  // read header
79  w = bytestream_get_le16(&buf);
80  h = bytestream_get_le16(&buf);
81  if (av_image_check_size(w, h, 0, avctx) < 0)
82  return -1;
83  x = bytestream_get_le16(&buf);
84  y = bytestream_get_le16(&buf);
85  // skip bottom right position, it gives no new information
86  bytestream_get_le16(&buf);
87  bytestream_get_le16(&buf);
88  // The following value is supposed to indicate the start offset
89  // (relative to the palette) of the data for the second field,
90  // however there are files in which it has a bogus value and thus
91  // we just ignore it
92  bytestream_get_le16(&buf);
93 
94  // allocate sub and set values
95  sub->rects = av_mallocz(sizeof(*sub->rects));
96  if (!sub->rects)
97  return AVERROR(ENOMEM);
98 
99  sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));
100  if (!sub->rects[0]) {
101  av_freep(&sub->rects);
102  return AVERROR(ENOMEM);
103  }
104  sub->rects[0]->x = x; sub->rects[0]->y = y;
105  sub->rects[0]->w = w; sub->rects[0]->h = h;
106  sub->rects[0]->type = SUBTITLE_BITMAP;
107  sub->rects[0]->linesize[0] = w;
108  sub->rects[0]->data[0] = av_malloc(w * h);
109  sub->rects[0]->nb_colors = 4;
110  sub->rects[0]->data[1] = av_mallocz(AVPALETTE_SIZE);
111  if (!sub->rects[0]->data[0] || !sub->rects[0]->data[1]) {
112  av_freep(&sub->rects[0]->data[1]);
113  av_freep(&sub->rects[0]->data[0]);
114  av_freep(&sub->rects[0]);
115  av_freep(&sub->rects);
116  return AVERROR(ENOMEM);
117  }
118  sub->num_rects = 1;
119 
120  // read palette
121  for (i = 0; i < sub->rects[0]->nb_colors; i++)
122  ((uint32_t*)sub->rects[0]->data[1])[i] = bytestream_get_be24(&buf);
123 
124  if (!has_alpha) {
125  // make all except background (first entry) non-transparent
126  for (i = 1; i < sub->rects[0]->nb_colors; i++)
127  ((uint32_t *)sub->rects[0]->data[1])[i] |= 0xff000000;
128  } else {
129  for (i = 0; i < sub->rects[0]->nb_colors; i++)
130  ((uint32_t *)sub->rects[0]->data[1])[i] |= *buf++ << 24;
131  }
132 
133 #if FF_API_AVPICTURE
135 {
137  int j;
138  rect = sub->rects[0];
139  for (j = 0; j < 4; j++) {
140  rect->pict.data[j] = rect->data[j];
141  rect->pict.linesize[j] = rect->linesize[j];
142  }
143 }
145 #endif
146 
147  // process RLE-compressed data
148  init_get_bits(&gb, buf, (buf_end - buf) * 8);
149  bitmap = sub->rects[0]->data[0];
150  for (y = 0; y < h; y++) {
151  // interlaced: do odd lines
152  if (y == (h + 1) / 2) bitmap = sub->rects[0]->data[0] + w;
153  for (x = 0; x < w; ) {
154  int log2 = ff_log2_tab[show_bits(&gb, 8)];
155  int run = get_bits(&gb, 14 - 4 * (log2 >> 1));
156  int color = get_bits(&gb, 2);
157  run = FFMIN(run, w - x);
158  // run length 0 means till end of row
159  if (!run) run = w - x;
160  memset(bitmap, color, run);
161  bitmap += run;
162  x += run;
163  }
164  // interlaced, skip every second line
165  bitmap += w;
166  align_get_bits(&gb);
167  }
168  *data_size = 1;
169  return buf_size;
170 }
171 
173  .name = "xsub",
174  .long_name = NULL_IF_CONFIG_SMALL("XSUB"),
175  .type = AVMEDIA_TYPE_SUBTITLE,
176  .id = AV_CODEC_ID_XSUB,
177  .init = decode_init,
178  .decode = decode_frame,
179 };
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:101
misc image utilities
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:247
int size
Definition: avcodec.h:1602
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1904
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:252
uint8_t run
Definition: svq3.c:206
AVCodec.
Definition: avcodec.h:3601
attribute_deprecated AVPicture pict
Definition: avcodec.h:3934
#define log2(x)
Definition: libm.h:404
uint8_t
#define av_cold
Definition: attributes.h:82
#define av_malloc(s)
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:73
#define AVPALETTE_SIZE
Definition: pixfmt.h:32
attribute_deprecated int linesize[AV_NUM_DATA_POINTERS]
number of bytes per line
Definition: avcodec.h:3894
static const uint8_t tc_muls[9]
Definition: xsubdec.c:34
uint8_t * data
Definition: avcodec.h:1601
bitstream reader API header.
#define av_log(a,...)
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
static av_cold int decode_init(AVCodecContext *avctx)
Definition: xsubdec.c:28
#define AVERROR(e)
Definition: error.h:43
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
Definition: xsubdec.c:49
static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time)
Definition: xsubdec.c:36
const char * name
Name of the codec implementation.
Definition: avcodec.h:3608
static const uint8_t tc_offsets[9]
Definition: xsubdec.c:33
int av_image_check_size(unsigned int w, unsigned int h, int log_offset, void *log_ctx)
Check if the given dimension of an image is valid, meaning that all bytes of the image can be address...
Definition: imgutils.c:251
A bitmap, pict will be set.
Definition: avcodec.h:3905
int linesize[4]
Definition: avcodec.h:3941
#define FFMIN(a, b)
Definition: common.h:96
static unsigned int show_bits(GetBitContext *s, int n)
Show 1-25 bits.
Definition: get_bits.h:282
attribute_deprecated uint8_t * data[AV_NUM_DATA_POINTERS]
pointers to the image data planes
Definition: avcodec.h:3892
uint8_t * data[4]
data+linesize for the bitmap of this subtitle.
Definition: avcodec.h:3940
const uint8_t ff_log2_tab[256]
Definition: log2_tab.c:23
Libavcodec external API header.
#define AV_TIME_BASE_Q
Internal time base represented as fractional value.
Definition: avutil.h:254
main external API structure.
Definition: avcodec.h:1676
AVCodec ff_xsub_decoder
Definition: xsubdec.c:172
unsigned int codec_tag
fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
Definition: avcodec.h:1708
void * buf
Definition: avisynth_c.h:690
Definition: f_ebur128.c:91
Rational number (pair of numerator and denominator).
Definition: rational.h:58
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:410
#define FF_DISABLE_DEPRECATION_WARNINGS
Definition: internal.h:80
#define FF_ENABLE_DEPRECATION_WARNINGS
Definition: internal.h:81
static AVCodec * c
static const uint8_t * align_get_bits(GetBitContext *s)
Definition: get_bits.h:449
#define av_freep(p)
#define MKTAG(a, b, c, d)
Definition: common.h:342
This structure stores compressed data.
Definition: avcodec.h:1578
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1594
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:242