f652198e5b1d1925ce96a981333b8c34727fa4b3
[libav.git] / libavcodec / escape124.c
1 /*
2 * Escape 124 Video Decoder
3 * Copyright (C) 2008 Eli Friedman (eli.friedman@gmail.com)
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "avcodec.h"
23 #include "internal.h"
24
25 #define BITSTREAM_READER_LE
26 #include "get_bits.h"
27
28 typedef union MacroBlock {
29 uint16_t pixels[4];
30 uint32_t pixels32[2];
31 } MacroBlock;
32
33 typedef union SuperBlock {
34 uint16_t pixels[64];
35 uint32_t pixels32[32];
36 } SuperBlock;
37
38 typedef struct CodeBook {
39 unsigned depth;
40 unsigned size;
41 MacroBlock* blocks;
42 } CodeBook;
43
44 typedef struct Escape124Context {
45 AVFrame *frame;
46
47 unsigned num_superblocks;
48
49 CodeBook codebooks[3];
50 } Escape124Context;
51
52 static int can_safely_read(GetBitContext* gb, int bits) {
53 return get_bits_left(gb) >= bits;
54 }
55
56 /**
57 * Initialize the decoder
58 * @param avctx decoder context
59 * @return 0 success, negative on error
60 */
61 static av_cold int escape124_decode_init(AVCodecContext *avctx)
62 {
63 Escape124Context *s = avctx->priv_data;
64
65 avctx->pix_fmt = AV_PIX_FMT_RGB555;
66
67 s->num_superblocks = ((unsigned)avctx->width / 8) *
68 ((unsigned)avctx->height / 8);
69
70 s->frame = av_frame_alloc();
71 if (!s->frame)
72 return AVERROR(ENOMEM);
73
74 return 0;
75 }
76
77 static av_cold int escape124_decode_close(AVCodecContext *avctx)
78 {
79 unsigned i;
80 Escape124Context *s = avctx->priv_data;
81
82 for (i = 0; i < 3; i++)
83 av_free(s->codebooks[i].blocks);
84
85 av_frame_free(&s->frame);
86
87 return 0;
88 }
89
90 static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
91 unsigned size)
92 {
93 unsigned i, j;
94 CodeBook cb = { 0 };
95
96 if (!can_safely_read(gb, size * 34))
97 return cb;
98
99 if (size >= INT_MAX / sizeof(MacroBlock))
100 return cb;
101 cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
102 if (!cb.blocks)
103 return cb;
104
105 cb.depth = depth;
106 cb.size = size;
107 for (i = 0; i < size; i++) {
108 unsigned mask_bits = get_bits(gb, 4);
109 unsigned color0 = get_bits(gb, 15);
110 unsigned color1 = get_bits(gb, 15);
111
112 for (j = 0; j < 4; j++) {
113 if (mask_bits & (1 << j))
114 cb.blocks[i].pixels[j] = color1;
115 else
116 cb.blocks[i].pixels[j] = color0;
117 }
118 }
119 return cb;
120 }
121
122 static unsigned decode_skip_count(GetBitContext* gb)
123 {
124 unsigned value;
125 // This function reads a maximum of 23 bits,
126 // which is within the padding space
127 if (!can_safely_read(gb, 1))
128 return -1;
129 value = get_bits1(gb);
130 if (!value)
131 return value;
132
133 value += get_bits(gb, 3);
134 if (value != (1 + ((1 << 3) - 1)))
135 return value;
136
137 value += get_bits(gb, 7);
138 if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
139 return value;
140
141 return value + get_bits(gb, 12);
142 }
143
144 static MacroBlock decode_macroblock(Escape124Context* s, GetBitContext* gb,
145 int* codebook_index, int superblock_index)
146 {
147 // This function reads a maximum of 22 bits; the callers
148 // guard this function appropriately
149 unsigned block_index, depth;
150 int value = get_bits1(gb);
151 if (value) {
152 static const char transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
153 value = get_bits1(gb);
154 *codebook_index = transitions[*codebook_index][value];
155 }
156
157 depth = s->codebooks[*codebook_index].depth;
158
159 // depth = 0 means that this shouldn't read any bits;
160 // in theory, this is the same as get_bits(gb, 0), but
161 // that doesn't actually work.
162 block_index = depth ? get_bits(gb, depth) : 0;
163
164 if (*codebook_index == 1) {
165 block_index += superblock_index << s->codebooks[1].depth;
166 }
167
168 // This condition can occur with invalid bitstreams and
169 // *codebook_index == 2
170 if (block_index >= s->codebooks[*codebook_index].size)
171 return (MacroBlock) { { 0 } };
172
173 return s->codebooks[*codebook_index].blocks[block_index];
174 }
175
176 static void insert_mb_into_sb(SuperBlock* sb, MacroBlock mb, unsigned index) {
177 // Formula: ((index / 4) * 16 + (index % 4) * 2) / 2
178 uint32_t *dst = sb->pixels32 + index + (index & -4);
179
180 // This technically violates C99 aliasing rules, but it should be safe.
181 dst[0] = mb.pixels32[0];
182 dst[4] = mb.pixels32[1];
183 }
184
185 static void copy_superblock(uint16_t* dest, unsigned dest_stride,
186 uint16_t* src, unsigned src_stride)
187 {
188 unsigned y;
189 if (src)
190 for (y = 0; y < 8; y++)
191 memcpy(dest + y * dest_stride, src + y * src_stride,
192 sizeof(uint16_t) * 8);
193 else
194 for (y = 0; y < 8; y++)
195 memset(dest + y * dest_stride, 0, sizeof(uint16_t) * 8);
196 }
197
198 static const uint16_t mask_matrix[] = {0x1, 0x2, 0x10, 0x20,
199 0x4, 0x8, 0x40, 0x80,
200 0x100, 0x200, 0x1000, 0x2000,
201 0x400, 0x800, 0x4000, 0x8000};
202
203 static int escape124_decode_frame(AVCodecContext *avctx,
204 void *data, int *got_frame,
205 AVPacket *avpkt)
206 {
207 const uint8_t *buf = avpkt->data;
208 int buf_size = avpkt->size;
209 Escape124Context *s = avctx->priv_data;
210 AVFrame *frame = data;
211
212 GetBitContext gb;
213 unsigned frame_flags, frame_size;
214 unsigned i;
215
216 unsigned superblock_index, cb_index = 1,
217 superblock_col_index = 0,
218 superblocks_per_row = avctx->width / 8, skip = -1;
219
220 uint16_t* old_frame_data, *new_frame_data;
221 unsigned old_stride, new_stride;
222 int ret;
223
224 init_get_bits(&gb, buf, buf_size * 8);
225
226 // This call also guards the potential depth reads for the
227 // codebook unpacking.
228 if (!can_safely_read(&gb, 64))
229 return -1;
230
231 frame_flags = get_bits_long(&gb, 32);
232 frame_size = get_bits_long(&gb, 32);
233
234 // Leave last frame unchanged
235 // FIXME: Is this necessary? I haven't seen it in any real samples
236 if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) {
237 if (!s->frame->data[0])
238 return AVERROR_INVALIDDATA;
239
240 av_log(NULL, AV_LOG_DEBUG, "Skipping frame\n");
241
242 *got_frame = 1;
243 if ((ret = av_frame_ref(frame, s->frame)) < 0)
244 return ret;
245
246 return frame_size;
247 }
248
249 for (i = 0; i < 3; i++) {
250 if (frame_flags & (1 << (17 + i))) {
251 unsigned cb_depth, cb_size;
252 if (i == 2) {
253 // This codebook can be cut off at places other than
254 // powers of 2, leaving some of the entries undefined.
255 cb_size = get_bits_long(&gb, 20);
256 cb_depth = av_log2(cb_size - 1) + 1;
257 } else {
258 cb_depth = get_bits(&gb, 4);
259 if (i == 0) {
260 // This is the most basic codebook: pow(2,depth) entries
261 // for a depth-length key
262 cb_size = 1 << cb_depth;
263 } else {
264 // This codebook varies per superblock
265 // FIXME: I don't think this handles integer overflow
266 // properly
267 cb_size = s->num_superblocks << cb_depth;
268 }
269 }
270 av_free(s->codebooks[i].blocks);
271 s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
272 if (!s->codebooks[i].blocks)
273 return -1;
274 }
275 }
276
277 if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0) {
278 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
279 return ret;
280 }
281
282 new_frame_data = (uint16_t*)frame->data[0];
283 new_stride = frame->linesize[0] / 2;
284 old_frame_data = (uint16_t*)s->frame->data[0];
285 old_stride = s->frame->linesize[0] / 2;
286
287 for (superblock_index = 0; superblock_index < s->num_superblocks;
288 superblock_index++) {
289 MacroBlock mb;
290 SuperBlock sb;
291 unsigned multi_mask = 0;
292
293 if (skip == -1) {
294 // Note that this call will make us skip the rest of the blocks
295 // if the frame prematurely ends
296 skip = decode_skip_count(&gb);
297 }
298
299 if (skip) {
300 copy_superblock(new_frame_data, new_stride,
301 old_frame_data, old_stride);
302 } else {
303 copy_superblock(sb.pixels, 8,
304 old_frame_data, old_stride);
305
306 while (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
307 unsigned mask;
308 mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
309 mask = get_bits(&gb, 16);
310 multi_mask |= mask;
311 for (i = 0; i < 16; i++) {
312 if (mask & mask_matrix[i]) {
313 insert_mb_into_sb(&sb, mb, i);
314 }
315 }
316 }
317
318 if (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
319 unsigned inv_mask = get_bits(&gb, 4);
320 for (i = 0; i < 4; i++) {
321 if (inv_mask & (1 << i)) {
322 multi_mask ^= 0xF << i*4;
323 } else {
324 multi_mask ^= get_bits(&gb, 4) << i*4;
325 }
326 }
327
328 for (i = 0; i < 16; i++) {
329 if (multi_mask & mask_matrix[i]) {
330 if (!can_safely_read(&gb, 1))
331 break;
332 mb = decode_macroblock(s, &gb, &cb_index,
333 superblock_index);
334 insert_mb_into_sb(&sb, mb, i);
335 }
336 }
337 } else if (frame_flags & (1 << 16)) {
338 while (can_safely_read(&gb, 1) && !get_bits1(&gb)) {
339 mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
340 insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
341 }
342 }
343
344 copy_superblock(new_frame_data, new_stride, sb.pixels, 8);
345 }
346
347 superblock_col_index++;
348 new_frame_data += 8;
349 if (old_frame_data)
350 old_frame_data += 8;
351 if (superblock_col_index == superblocks_per_row) {
352 new_frame_data += new_stride * 8 - superblocks_per_row * 8;
353 if (old_frame_data)
354 old_frame_data += old_stride * 8 - superblocks_per_row * 8;
355 superblock_col_index = 0;
356 }
357 skip--;
358 }
359
360 av_log(NULL, AV_LOG_DEBUG,
361 "Escape sizes: %i, %i, %i\n",
362 frame_size, buf_size, get_bits_count(&gb) / 8);
363
364 av_frame_unref(s->frame);
365 if ((ret = av_frame_ref(s->frame, frame)) < 0)
366 return ret;
367
368 *got_frame = 1;
369
370 return frame_size;
371 }
372
373
374 AVCodec ff_escape124_decoder = {
375 .name = "escape124",
376 .long_name = NULL_IF_CONFIG_SMALL("Escape 124"),
377 .type = AVMEDIA_TYPE_VIDEO,
378 .id = AV_CODEC_ID_ESCAPE124,
379 .priv_data_size = sizeof(Escape124Context),
380 .init = escape124_decode_init,
381 .close = escape124_decode_close,
382 .decode = escape124_decode_frame,
383 .capabilities = AV_CODEC_CAP_DR1,
384 };