FFmpeg  4.4.5
xsubenc.c
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1 /*
2  * DivX (XSUB) subtitle encoder
3  * Copyright (c) 2005 DivX, Inc.
4  * Copyright (c) 2009 Bjorn Axelsson
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include "avcodec.h"
24 #include "bytestream.h"
25 #include "internal.h"
26 #include "put_bits.h"
27 
28 /**
29  * Number of pixels to pad left and right.
30  *
31  * The official encoder pads the subtitles with two pixels on either side,
32  * but until we find out why, we won't do it (we will pad to have width
33  * divisible by 2 though).
34  */
35 #define PADDING 0
36 #define PADDING_COLOR 0
37 
38 /**
39  * Encode a single color run. At most 16 bits will be used.
40  * @param len length of the run, values > 255 mean "until end of line", may not be < 0.
41  * @param color color to encode, only the lowest two bits are used and all others must be 0.
42  */
43 static void put_xsub_rle(PutBitContext *pb, int len, int color)
44 {
45  if (len <= 255)
46  put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len);
47  else
48  put_bits(pb, 14, 0);
49  put_bits(pb, 2, color);
50 }
51 
52 /**
53  * Encode a 4-color bitmap with XSUB rle.
54  *
55  * The encoded bitmap may be wider than the source bitmap due to padding.
56  */
57 static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap,
58  int linesize, int w, int h)
59 {
60  int x0, x1, y, len, color = PADDING_COLOR;
61 
62  for (y = 0; y < h; y++) {
63  x0 = 0;
64  while (x0 < w) {
65  // Make sure we have enough room for at least one run and padding
66  if (pb->size_in_bits - put_bits_count(pb) < 7*8)
68 
69  x1 = x0;
70  color = bitmap[x1++] & 3;
71  while (x1 < w && (bitmap[x1] & 3) == color)
72  x1++;
73  len = x1 - x0;
74  if (PADDING && x0 == 0) {
75  if (color == PADDING_COLOR) {
76  len += PADDING;
77  x0 -= PADDING;
78  } else
80  }
81 
82  // Run can't be longer than 255, unless it is the rest of a row
83  if (x1 == w && color == PADDING_COLOR) {
84  len += PADDING + (w&1);
85  } else
86  len = FFMIN(len, 255);
87  put_xsub_rle(pb, len, color);
88 
89  x0 += len;
90  }
91  if (color != PADDING_COLOR && (PADDING + (w&1)))
92  put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR);
93 
94  align_put_bits(pb);
95 
96  bitmap += linesize;
97  }
98 
99  return 0;
100 }
101 
102 static int make_tc(uint64_t ms, int *tc)
103 {
104  static const int tc_divs[3] = { 1000, 60, 60 };
105  int i;
106  for (i=0; i<3; i++) {
107  tc[i] = ms % tc_divs[i];
108  ms /= tc_divs[i];
109  }
110  tc[3] = ms;
111  return ms > 99;
112 }
113 
114 static int xsub_encode(AVCodecContext *avctx, unsigned char *buf,
115  int bufsize, const AVSubtitle *h)
116 {
117  uint64_t startTime = h->pts / 1000; // FIXME: need better solution...
118  uint64_t endTime = startTime + h->end_display_time - h->start_display_time;
119  int start_tc[4], end_tc[4];
120  uint8_t *hdr = buf + 27; // Point behind the timestamp
121  uint8_t *rlelenptr;
122  uint16_t width, height;
123  int i;
124  PutBitContext pb;
125 
126  if (bufsize < 27 + 7*2 + 4*3) {
127  av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n");
129  }
130 
131  // TODO: support multiple rects
132  if (h->num_rects != 1)
133  av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects);
134 
135 #if FF_API_AVPICTURE
137  if (!h->rects[0]->data[0]) {
138  AVSubtitleRect *rect = h->rects[0];
139  int j;
140  for (j = 0; j < 4; j++) {
141  rect->data[j] = rect->pict.data[j];
142  rect->linesize[j] = rect->pict.linesize[j];
143  }
144  }
146 #endif
147 
148  // TODO: render text-based subtitles into bitmaps
149  if (!h->rects[0]->data[0] || !h->rects[0]->data[1]) {
150  av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n");
151  return AVERROR(EINVAL);
152  }
153 
154  // TODO: color reduction, similar to dvdsub encoder
155  if (h->rects[0]->nb_colors > 4)
156  av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors);
157 
158  // TODO: Palette swapping if color zero is not transparent
159  if (((uint32_t *)h->rects[0]->data[1])[0] & 0xff000000)
160  av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n");
161 
162  if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) {
163  av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n");
164  return AVERROR(EINVAL);
165  }
166 
167  snprintf(buf, 28,
168  "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]",
169  start_tc[3], start_tc[2], start_tc[1], start_tc[0],
170  end_tc[3], end_tc[2], end_tc[1], end_tc[0]);
171 
172  // Width and height must probably be multiples of 2.
173  // 2 pixels required on either side of subtitle.
174  // Possibly due to limitations of hardware renderers.
175  // TODO: check if the bitmap is already padded
176  width = FFALIGN(h->rects[0]->w, 2) + PADDING * 2;
177  height = FFALIGN(h->rects[0]->h, 2);
178 
179  bytestream_put_le16(&hdr, width);
180  bytestream_put_le16(&hdr, height);
181  bytestream_put_le16(&hdr, h->rects[0]->x);
182  bytestream_put_le16(&hdr, h->rects[0]->y);
183  bytestream_put_le16(&hdr, h->rects[0]->x + width -1);
184  bytestream_put_le16(&hdr, h->rects[0]->y + height -1);
185 
186  rlelenptr = hdr; // Will store length of first field here later.
187  hdr+=2;
188 
189  // Palette
190  for (i=0; i<4; i++)
191  bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->data[1])[i]);
192 
193  // Bitmap
194  // RLE buffer. Reserve 2 bytes for possible padding after the last row.
195  init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2);
196  if (xsub_encode_rle(&pb, h->rects[0]->data[0],
197  h->rects[0]->linesize[0] * 2,
198  h->rects[0]->w, (h->rects[0]->h + 1) >> 1))
200  bytestream_put_le16(&rlelenptr, put_bits_count(&pb) >> 3); // Length of first field
201 
202  if (xsub_encode_rle(&pb, h->rects[0]->data[0] + h->rects[0]->linesize[0],
203  h->rects[0]->linesize[0] * 2,
204  h->rects[0]->w, h->rects[0]->h >> 1))
206 
207  // Enforce total height to be a multiple of 2
208  if (h->rects[0]->h & 1) {
209  put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR);
210  }
211 
212  flush_put_bits(&pb);
213 
214  return hdr - buf + put_bits_count(&pb)/8;
215 }
216 
218 {
219  if (!avctx->codec_tag)
220  avctx->codec_tag = MKTAG('D','X','S','B');
221 
222  avctx->bits_per_coded_sample = 4;
223 
224  return 0;
225 }
226 
228  .name = "xsub",
229  .long_name = NULL_IF_CONFIG_SMALL("DivX subtitles (XSUB)"),
230  .type = AVMEDIA_TYPE_SUBTITLE,
231  .id = AV_CODEC_ID_XSUB,
232  .init = xsub_encoder_init,
233  .encode_sub = xsub_encode,
234  .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
235 };
#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
@ AV_CODEC_ID_XSUB
Definition: codec_id.h:526
#define AVERROR_BUFFER_TOO_SMALL
Buffer too small.
Definition: error.h:51
#define AVERROR(e)
Definition: error.h:43
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:200
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
@ AVMEDIA_TYPE_SUBTITLE
Definition: avutil.h:204
int i
Definition: input.c:407
const uint8_t ff_log2_tab[256]
Definition: log2_tab.c:23
static void put_bits(Jpeg2000EncoderContext *s, int val, int n)
put n times val bit
Definition: j2kenc.c:218
#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
uint8_t w
Definition: llviddspenc.c:39
#define FFALIGN(x, a)
Definition: macros.h:48
bitstream writer API
static void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
Initialize the PutBitContext s.
Definition: put_bits.h:57
static int put_bits_count(PutBitContext *s)
Definition: put_bits.h:76
static void flush_put_bits(PutBitContext *s)
Pad the end of the output stream with zeros.
Definition: put_bits.h:110
static void align_put_bits(PutBitContext *s)
Pad the bitstream with zeros up to the next byte boundary.
Definition: put_bits.h:386
#define tc
Definition: regdef.h:69
#define snprintf
Definition: snprintf.h:34
main external API structure.
Definition: avcodec.h:536
unsigned int codec_tag
fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
Definition: avcodec.h:561
int bits_per_coded_sample
bits per sample/pixel from the demuxer (needed for huffyuv).
Definition: avcodec.h:1740
AVCodec.
Definition: codec.h:197
const char * name
Name of the codec implementation.
Definition: codec.h:204
int size_in_bits
Definition: put_bits.h:48
Definition: f_ebur128.c:91
#define av_log(a,...)
#define height
#define width
int len
#define PADDING_COLOR
Definition: xsubenc.c:36
#define PADDING
Number of pixels to pad left and right.
Definition: xsubenc.c:35
static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap, int linesize, int w, int h)
Encode a 4-color bitmap with XSUB rle.
Definition: xsubenc.c:57
static int make_tc(uint64_t ms, int *tc)
Definition: xsubenc.c:102
static void put_xsub_rle(PutBitContext *pb, int len, int color)
Encode a single color run.
Definition: xsubenc.c:43
static int xsub_encode(AVCodecContext *avctx, unsigned char *buf, int bufsize, const AVSubtitle *h)
Definition: xsubenc.c:114
static av_cold int xsub_encoder_init(AVCodecContext *avctx)
Definition: xsubenc.c:217
AVCodec ff_xsub_encoder
Definition: xsubenc.c:227