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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');
61  int j;
62 
63  // check that at least header fits
64  if (buf_size < 27 + 7 * 2 + 4 * (3 + has_alpha)) {
65  av_log(avctx, AV_LOG_ERROR, "coded frame size %d too small\n", buf_size);
66  return -1;
67  }
68 
69  // read start and end time
70  if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') {
71  av_log(avctx, AV_LOG_ERROR, "invalid time code\n");
72  return -1;
73  }
74  if (avpkt->pts != AV_NOPTS_VALUE)
75  packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000});
76  sub->start_display_time = parse_timecode(buf + 1, packet_time);
77  sub->end_display_time = parse_timecode(buf + 14, packet_time);
78  buf += 27;
79 
80  // read header
81  w = bytestream_get_le16(&buf);
82  h = bytestream_get_le16(&buf);
83  if (av_image_check_size(w, h, 0, avctx) < 0)
84  return -1;
85  x = bytestream_get_le16(&buf);
86  y = bytestream_get_le16(&buf);
87  // skip bottom right position, it gives no new information
88  bytestream_get_le16(&buf);
89  bytestream_get_le16(&buf);
90  // The following value is supposed to indicate the start offset
91  // (relative to the palette) of the data for the second field,
92  // however there are files in which it has a bogus value and thus
93  // we just ignore it
94  bytestream_get_le16(&buf);
95 
96  // allocate sub and set values
97  sub->rects = av_mallocz(sizeof(*sub->rects));
98  if (!sub->rects)
99  return AVERROR(ENOMEM);
100 
101  sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));
102  if (!sub->rects[0]) {
103  av_freep(&sub->rects);
104  return AVERROR(ENOMEM);
105  }
106  sub->rects[0]->x = x; sub->rects[0]->y = y;
107  sub->rects[0]->w = w; sub->rects[0]->h = h;
108  sub->rects[0]->type = SUBTITLE_BITMAP;
109  sub->rects[0]->linesize[0] = w;
110  sub->rects[0]->data[0] = av_malloc(w * h);
111  sub->rects[0]->nb_colors = 4;
112  sub->rects[0]->data[1] = av_mallocz(AVPALETTE_SIZE);
113  if (!sub->rects[0]->data[0] || !sub->rects[0]->data[1]) {
114  av_freep(&sub->rects[0]->data[1]);
115  av_freep(&sub->rects[0]->data[0]);
116  av_freep(&sub->rects[0]);
117  av_freep(&sub->rects);
118  return AVERROR(ENOMEM);
119  }
120  sub->num_rects = 1;
121 
122  // read palette
123  for (i = 0; i < sub->rects[0]->nb_colors; i++)
124  ((uint32_t*)sub->rects[0]->data[1])[i] = bytestream_get_be24(&buf);
125 
126  if (!has_alpha) {
127  // make all except background (first entry) non-transparent
128  for (i = 1; i < sub->rects[0]->nb_colors; i++)
129  ((uint32_t *)sub->rects[0]->data[1])[i] |= 0xff000000;
130  } else {
131  for (i = 0; i < sub->rects[0]->nb_colors; i++)
132  ((uint32_t *)sub->rects[0]->data[1])[i] |= *buf++ << 24;
133  }
134 
135 #if FF_API_AVPICTURE
137  rect = sub->rects[0];
138  for (j = 0; j < 4; j++) {
139  rect->pict.data[j] = rect->data[j];
140  rect->pict.linesize[j] = rect->linesize[j];
141  }
143 #endif
144 
145  // process RLE-compressed data
146  init_get_bits(&gb, buf, (buf_end - buf) * 8);
147  bitmap = sub->rects[0]->data[0];
148  for (y = 0; y < h; y++) {
149  // interlaced: do odd lines
150  if (y == (h + 1) / 2) bitmap = sub->rects[0]->data[0] + w;
151  for (x = 0; x < w; ) {
152  int log2 = ff_log2_tab[show_bits(&gb, 8)];
153  int run = get_bits(&gb, 14 - 4 * (log2 >> 1));
154  int color = get_bits(&gb, 2);
155  run = FFMIN(run, w - x);
156  // run length 0 means till end of row
157  if (!run) run = w - x;
158  memset(bitmap, color, run);
159  bitmap += run;
160  x += run;
161  }
162  // interlaced, skip every second line
163  bitmap += w;
164  align_get_bits(&gb);
165  }
166  *data_size = 1;
167  return buf_size;
168 }
169 
171  .name = "xsub",
172  .long_name = NULL_IF_CONFIG_SMALL("XSUB"),
173  .type = AVMEDIA_TYPE_SUBTITLE,
174  .id = AV_CODEC_ID_XSUB,
175  .init = decode_init,
176  .decode = decode_frame,
177 };
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:260
int size
Definition: avcodec.h:1578
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1870
uint8_t run
Definition: svq3.c:192
AVCodec.
Definition: avcodec.h:3535
#define log2(x)
Definition: libm.h:404
uint8_t
#define av_cold
Definition: attributes.h:82
#define av_malloc(s)
8 bit with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:73
#define AVPALETTE_SIZE
Definition: pixfmt.h:32
static const uint8_t tc_muls[9]
Definition: xsubdec.c:34
uint8_t * data
Definition: avcodec.h:1577
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:3542
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:3839
#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:295
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:252
main external API structure.
Definition: avcodec.h:1642
AVCodec ff_xsub_decoder
Definition: xsubdec.c:170
unsigned int codec_tag
fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
Definition: avcodec.h:1674
void * buf
Definition: avisynth_c.h:553
Definition: f_ebur128.c:91
rational number numerator/denominator
Definition: rational.h:43
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:418
#define FF_DISABLE_DEPRECATION_WARNINGS
Definition: internal.h:80
static double c[64]
#define FF_ENABLE_DEPRECATION_WARNINGS
Definition: internal.h:81
static const uint8_t * align_get_bits(GetBitContext *s)
Definition: get_bits.h:457
#define av_freep(p)
#define MKTAG(a, b, c, d)
Definition: common.h:342
This structure stores compressed data.
Definition: avcodec.h:1554
void * av_mallocz(size_t size)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...
Definition: mem.c:252
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1570
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:240