FFmpeg  4.4.5
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 #include "internal.h"
28 
29 static av_cold int decode_init(AVCodecContext *avctx) {
30  avctx->pix_fmt = AV_PIX_FMT_PAL8;
31  return 0;
32 }
33 
34 static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 };
35 static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 };
36 
37 static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {
38  int i;
39  int64_t ms = 0;
40  if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.')
41  return AV_NOPTS_VALUE;
42  for (i = 0; i < sizeof(tc_offsets); i++) {
43  uint8_t c = buf[tc_offsets[i]] - '0';
44  if (c > 9) return AV_NOPTS_VALUE;
45  ms = (ms + c) * tc_muls[i];
46  }
47  return ms - packet_time;
48 }
49 
50 static int decode_frame(AVCodecContext *avctx, void *data, int *got_sub_ptr,
51  AVPacket *avpkt) {
52  const uint8_t *buf = avpkt->data;
53  int buf_size = avpkt->size;
54  AVSubtitle *sub = data;
55  const uint8_t *buf_end = buf + buf_size;
56  uint8_t *bitmap;
57  int w, h, x, y, i, ret;
58  int64_t packet_time = 0;
59  GetBitContext gb;
60  int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A');
61  int64_t start_display_time, end_display_time;
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 
77  sub->start_display_time = start_display_time = parse_timecode(buf + 1, packet_time);
78  sub->end_display_time = end_display_time = parse_timecode(buf + 14, packet_time);
79  if (sub->start_display_time != start_display_time ||
80  sub-> end_display_time != end_display_time) {
81  av_log(avctx, AV_LOG_ERROR, "time code not representable in 32bit\n");
82  return -1;
83  }
84  buf += 27;
85 
86  // read header
87  w = bytestream_get_le16(&buf);
88  h = bytestream_get_le16(&buf);
89  if (av_image_check_size(w, h, 0, avctx) < 0)
90  return -1;
91  x = bytestream_get_le16(&buf);
92  y = bytestream_get_le16(&buf);
93  // skip bottom right position, it gives no new information
94  bytestream_get_le16(&buf);
95  bytestream_get_le16(&buf);
96  // The following value is supposed to indicate the start offset
97  // (relative to the palette) of the data for the second field,
98  // however there are files in which it has a bogus value and thus
99  // we just ignore it
100  bytestream_get_le16(&buf);
101 
102  if (buf_end - buf < h + 3*4)
103  return AVERROR_INVALIDDATA;
104 
105  // allocate sub and set values
106  sub->rects = av_mallocz(sizeof(*sub->rects));
107  if (!sub->rects)
108  return AVERROR(ENOMEM);
109 
110  sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));
111  if (!sub->rects[0]) {
112  av_freep(&sub->rects);
113  return AVERROR(ENOMEM);
114  }
115  sub->rects[0]->x = x; sub->rects[0]->y = y;
116  sub->rects[0]->w = w; sub->rects[0]->h = h;
117  sub->rects[0]->type = SUBTITLE_BITMAP;
118  sub->rects[0]->linesize[0] = w;
119  sub->rects[0]->data[0] = av_malloc(w * h);
120  sub->rects[0]->nb_colors = 4;
121  sub->rects[0]->data[1] = av_mallocz(AVPALETTE_SIZE);
122  if (!sub->rects[0]->data[0] || !sub->rects[0]->data[1]) {
123  av_freep(&sub->rects[0]->data[1]);
124  av_freep(&sub->rects[0]->data[0]);
125  av_freep(&sub->rects[0]);
126  av_freep(&sub->rects);
127  return AVERROR(ENOMEM);
128  }
129  sub->num_rects = 1;
130 
131  // read palette
132  for (i = 0; i < sub->rects[0]->nb_colors; i++)
133  ((uint32_t*)sub->rects[0]->data[1])[i] = bytestream_get_be24(&buf);
134 
135  if (!has_alpha) {
136  // make all except background (first entry) non-transparent
137  for (i = 1; i < sub->rects[0]->nb_colors; i++)
138  ((uint32_t *)sub->rects[0]->data[1])[i] |= 0xff000000;
139  } else {
140  for (i = 0; i < sub->rects[0]->nb_colors; i++)
141  ((uint32_t *)sub->rects[0]->data[1])[i] |= (unsigned)*buf++ << 24;
142  }
143 
144 #if FF_API_AVPICTURE
146 {
148  int j;
149  rect = sub->rects[0];
150  for (j = 0; j < 4; j++) {
151  rect->pict.data[j] = rect->data[j];
152  rect->pict.linesize[j] = rect->linesize[j];
153  }
154 }
156 #endif
157 
158  // process RLE-compressed data
159  if ((ret = init_get_bits8(&gb, buf, buf_end - buf)) < 0)
160  return ret;
161  bitmap = sub->rects[0]->data[0];
162  for (y = 0; y < h; y++) {
163  // interlaced: do odd lines
164  if (y == (h + 1) / 2) bitmap = sub->rects[0]->data[0] + w;
165  for (x = 0; x < w; ) {
166  int log2 = ff_log2_tab[show_bits(&gb, 8)];
167  int run = get_bits(&gb, 14 - 4 * (log2 >> 1));
168  int color = get_bits(&gb, 2);
169  run = FFMIN(run, w - x);
170  // run length 0 means till end of row
171  if (!run) run = w - x;
172  memset(bitmap, color, run);
173  bitmap += run;
174  x += run;
175  }
176  // interlaced, skip every second line
177  bitmap += w;
178  align_get_bits(&gb);
179  }
180  *got_sub_ptr = 1;
181  return buf_size;
182 }
183 
185  .name = "xsub",
186  .long_name = NULL_IF_CONFIG_SMALL("XSUB"),
187  .type = AVMEDIA_TYPE_SUBTITLE,
188  .id = AV_CODEC_ID_XSUB,
189  .init = decode_init,
190  .decode = decode_frame,
191  .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
192 };
#define av_cold
Definition: attributes.h:88
uint8_t
Libavcodec external API header.
#define FFMIN(a, b)
Definition: common.h:105
#define MKTAG(a, b, c, d)
Definition: common.h:478
long long int64_t
Definition: coverity.c:34
static float sub(float src0, float src1)
bitstream reader API header.
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:677
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:379
static const uint8_t * align_get_bits(GetBitContext *s)
Definition: get_bits.h:693
static unsigned int show_bits(GetBitContext *s, int n)
Show 1-25 bits.
Definition: get_bits.h:446
@ SUBTITLE_BITMAP
A bitmap, pict will be set.
Definition: avcodec.h:2670
@ AV_CODEC_ID_XSUB
Definition: codec_id.h:526
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
#define AVERROR(e)
Definition: error.h:43
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
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
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:237
@ AVMEDIA_TYPE_SUBTITLE
Definition: avutil.h:204
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:317
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
#define AV_TIME_BASE_Q
Internal time base represented as fractional value.
Definition: avutil.h:260
for(j=16;j >0;--j)
misc image utilities
int i
Definition: input.c:407
const uint8_t ff_log2_tab[256]
Definition: log2_tab.c:23
#define FF_CODEC_CAP_INIT_THREADSAFE
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: internal.h:41
common internal API header
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
#define FF_DISABLE_DEPRECATION_WARNINGS
Definition: internal.h:83
#define FF_ENABLE_DEPRECATION_WARNINGS
Definition: internal.h:84
#define log2(x)
Definition: libm.h:404
uint8_t w
Definition: llviddspenc.c:39
const char data[16]
Definition: mxf.c:142
@ AV_PIX_FMT_PAL8
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:77
#define AVPALETTE_SIZE
Definition: pixfmt.h:32
main external API structure.
Definition: avcodec.h:536
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:746
unsigned int codec_tag
fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
Definition: avcodec.h:561
AVCodec.
Definition: codec.h:197
const char * name
Name of the codec implementation.
Definition: codec.h:204
This structure stores compressed data.
Definition: packet.h:346
int size
Definition: packet.h:370
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:362
uint8_t * data
Definition: packet.h:369
Rational number (pair of numerator and denominator).
Definition: rational.h:58
Definition: f_ebur128.c:91
uint8_t run
Definition: svq3.c:205
#define av_freep(p)
#define av_malloc(s)
#define av_log(a,...)
static double c[64]
static av_cold int decode_init(AVCodecContext *avctx)
Definition: xsubdec.c:29
static const uint8_t tc_muls[9]
Definition: xsubdec.c:35
AVCodec ff_xsub_decoder
Definition: xsubdec.c:184
static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time)
Definition: xsubdec.c:37
static const uint8_t tc_offsets[9]
Definition: xsubdec.c:34
static int decode_frame(AVCodecContext *avctx, void *data, int *got_sub_ptr, AVPacket *avpkt)
Definition: xsubdec.c:50