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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 "put_bits.h"
26 
27 /**
28  * Number of pixels to pad left and right.
29  *
30  * The official encoder pads the subtitles with two pixels on either side,
31  * but until we find out why, we won't do it (we will pad to have width
32  * divisible by 2 though).
33  */
34 #define PADDING 0
35 #define PADDING_COLOR 0
36 
37 /**
38  * Encode a single color run. At most 16 bits will be used.
39  * @param len length of the run, values > 255 mean "until end of line", may not be < 0.
40  * @param color color to encode, only the lowest two bits are used and all others must be 0.
41  */
42 static void put_xsub_rle(PutBitContext *pb, int len, int color)
43 {
44  if (len <= 255)
45  put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len);
46  else
47  put_bits(pb, 14, 0);
48  put_bits(pb, 2, color);
49 }
50 
51 /**
52  * Encode a 4-color bitmap with XSUB rle.
53  *
54  * The encoded bitmap may be wider than the source bitmap due to padding.
55  */
56 static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap,
57  int linesize, int w, int h)
58 {
59  int x0, x1, y, len, color = PADDING_COLOR;
60 
61  for (y = 0; y < h; y++) {
62  x0 = 0;
63  while (x0 < w) {
64  // Make sure we have enough room for at least one run and padding
65  if (pb->size_in_bits - put_bits_count(pb) < 7*8)
66  return -1;
67 
68  x1 = x0;
69  color = bitmap[x1++] & 3;
70  while (x1 < w && (bitmap[x1] & 3) == color)
71  x1++;
72  len = x1 - x0;
73  if (PADDING && x0 == 0) {
74  if (color == PADDING_COLOR) {
75  len += PADDING;
76  x0 -= PADDING;
77  } else
79  }
80 
81  // Run can't be longer than 255, unless it is the rest of a row
82  if (x1 == w && color == PADDING_COLOR) {
83  len += PADDING + (w&1);
84  } else
85  len = FFMIN(len, 255);
86  put_xsub_rle(pb, len, color);
87 
88  x0 += len;
89  }
90  if (color != PADDING_COLOR && (PADDING + (w&1)))
91  put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR);
92 
94 
95  bitmap += linesize;
96  }
97 
98  return 0;
99 }
100 
101 static int make_tc(uint64_t ms, int *tc)
102 {
103  static const int tc_divs[3] = { 1000, 60, 60 };
104  int i;
105  for (i=0; i<3; i++) {
106  tc[i] = ms % tc_divs[i];
107  ms /= tc_divs[i];
108  }
109  tc[3] = ms;
110  return ms > 99;
111 }
112 
113 static int xsub_encode(AVCodecContext *avctx, unsigned char *buf,
114  int bufsize, const AVSubtitle *h)
115 {
116  uint64_t startTime = h->pts / 1000; // FIXME: need better solution...
117  uint64_t endTime = startTime + h->end_display_time - h->start_display_time;
118  int start_tc[4], end_tc[4];
119  uint8_t *hdr = buf + 27; // Point behind the timestamp
120  uint8_t *rlelenptr;
121  uint16_t width, height;
122  int i;
123  PutBitContext pb;
124 
125  if (bufsize < 27 + 7*2 + 4*3) {
126  av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n");
127  return -1;
128  }
129 
130  // TODO: support multiple rects
131  if (h->num_rects != 1)
132  av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects);
133 
134 #if FF_API_AVPICTURE
136  if (!h->rects[0]->data[0]) {
137  AVSubtitleRect *rect = h->rects[0];
138  int j;
139  for (j = 0; j < 4; j++) {
140  rect->data[j] = rect->pict.data[j];
141  rect->linesize[j] = rect->pict.linesize[j];
142  }
143  }
145 #endif
146 
147  // TODO: render text-based subtitles into bitmaps
148  if (!h->rects[0]->data[0] || !h->rects[0]->data[1]) {
149  av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n");
150  return -1;
151  }
152 
153  // TODO: color reduction, similar to dvdsub encoder
154  if (h->rects[0]->nb_colors > 4)
155  av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors);
156 
157  // TODO: Palette swapping if color zero is not transparent
158  if (((uint32_t *)h->rects[0]->data[1])[0] & 0xff000000)
159  av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n");
160 
161  if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) {
162  av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n");
163  return -1;
164  }
165 
166  snprintf(buf, 28,
167  "[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]",
168  start_tc[3], start_tc[2], start_tc[1], start_tc[0],
169  end_tc[3], end_tc[2], end_tc[1], end_tc[0]);
170 
171  // Width and height must probably be multiples of 2.
172  // 2 pixels required on either side of subtitle.
173  // Possibly due to limitations of hardware renderers.
174  // TODO: check if the bitmap is already padded
175  width = FFALIGN(h->rects[0]->w, 2) + PADDING * 2;
176  height = FFALIGN(h->rects[0]->h, 2);
177 
178  bytestream_put_le16(&hdr, width);
179  bytestream_put_le16(&hdr, height);
180  bytestream_put_le16(&hdr, h->rects[0]->x);
181  bytestream_put_le16(&hdr, h->rects[0]->y);
182  bytestream_put_le16(&hdr, h->rects[0]->x + width -1);
183  bytestream_put_le16(&hdr, h->rects[0]->y + height -1);
184 
185  rlelenptr = hdr; // Will store length of first field here later.
186  hdr+=2;
187 
188  // Palette
189  for (i=0; i<4; i++)
190  bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->data[1])[i]);
191 
192  // Bitmap
193  // RLE buffer. Reserve 2 bytes for possible padding after the last row.
194  init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2);
195  if (xsub_encode_rle(&pb, h->rects[0]->data[0],
196  h->rects[0]->linesize[0] * 2,
197  h->rects[0]->w, (h->rects[0]->h + 1) >> 1))
198  return -1;
199  bytestream_put_le16(&rlelenptr, put_bits_count(&pb) >> 3); // Length of first field
200 
201  if (xsub_encode_rle(&pb, h->rects[0]->data[0] + h->rects[0]->linesize[0],
202  h->rects[0]->linesize[0] * 2,
203  h->rects[0]->w, h->rects[0]->h >> 1))
204  return -1;
205 
206  // Enforce total height to be a multiple of 2
207  if (h->rects[0]->h & 1) {
208  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 };
#define PADDING
Number of pixels to pad left and right.
Definition: xsubenc.c:34
static void put_xsub_rle(PutBitContext *pb, int len, int color)
Encode a single color run.
Definition: xsubenc.c:42
int x
top left corner of pict, undefined when pict is not set
Definition: avcodec.h:3929
static void put_bits(Jpeg2000EncoderContext *s, int val, int n)
put n times val bit
Definition: j2kenc.c:206
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
int nb_colors
number of colors in pict, undefined when pict is not set
Definition: avcodec.h:3933
void avpriv_align_put_bits(PutBitContext *s)
Pad the bitstream with zeros up to the next byte boundary.
Definition: bitstream.c:49
#define tc
Definition: regdef.h:69
unsigned num_rects
Definition: avcodec.h:3967
AVCodec.
Definition: avcodec.h:3607
attribute_deprecated AVPicture pict
Definition: avcodec.h:3940
AVSubtitleRect ** rects
Definition: avcodec.h:3968
int w
width of pict, undefined when pict is not set
Definition: avcodec.h:3931
static int make_tc(uint64_t ms, int *tc)
Definition: xsubenc.c:101
uint8_t
#define av_cold
Definition: attributes.h:82
attribute_deprecated int linesize[AV_NUM_DATA_POINTERS]
number of bytes per line
Definition: avcodec.h:3900
#define height
int h
height of pict, undefined when pict is not set
Definition: avcodec.h:3932
int bits_per_coded_sample
bits per sample/pixel from the demuxer (needed for huffyuv).
Definition: avcodec.h:3077
#define FFALIGN(x, a)
Definition: macros.h:48
#define av_log(a,...)
int size_in_bits
Definition: put_bits.h:39
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
int y
top left corner of pict, undefined when pict is not set
Definition: avcodec.h:3930
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
static int xsub_encode(AVCodecContext *avctx, unsigned char *buf, int bufsize, const AVSubtitle *h)
Definition: xsubenc.c:113
const char * name
Name of the codec implementation.
Definition: avcodec.h:3614
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:56
static int put_bits_count(PutBitContext *s)
Definition: put_bits.h:85
uint32_t end_display_time
Definition: avcodec.h:3966
int64_t pts
Same as packet pts, in AV_TIME_BASE.
Definition: avcodec.h:3969
int linesize[4]
Definition: avcodec.h:3947
#define FFMIN(a, b)
Definition: common.h:96
#define width
attribute_deprecated uint8_t * data[AV_NUM_DATA_POINTERS]
pointers to the image data planes
Definition: avcodec.h:3898
AVCodec ff_xsub_encoder
Definition: xsubenc.c:227
uint8_t * data[4]
data+linesize for the bitmap of this subtitle.
Definition: avcodec.h:3946
const uint8_t ff_log2_tab[256]
Definition: log2_tab.c:23
Libavcodec external API header.
main external API structure.
Definition: avcodec.h:1682
unsigned int codec_tag
fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
Definition: avcodec.h:1714
void * buf
Definition: avisynth_c.h:690
Definition: f_ebur128.c:91
#define PADDING_COLOR
Definition: xsubenc.c:35
#define snprintf
Definition: snprintf.h:34
static av_cold int xsub_encoder_init(AVCodecContext *avctx)
Definition: xsubenc.c:217
#define FF_DISABLE_DEPRECATION_WARNINGS
Definition: internal.h:80
static void flush_put_bits(PutBitContext *s)
Pad the end of the output stream with zeros.
Definition: put_bits.h:101
uint32_t start_display_time
Definition: avcodec.h:3965
static void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
Initialize the PutBitContext s.
Definition: put_bits.h:48
#define FF_ENABLE_DEPRECATION_WARNINGS
Definition: internal.h:81
int len
#define MKTAG(a, b, c, d)
Definition: common.h:342
bitstream writer API