FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/escape124.c
Date: 2021-09-26 18:22:30
Exec Total Coverage
Lines: 143 165 86.7%
Branches: 82 106 77.4%

Line Branch Exec Source
1 /*
2 * Escape 124 Video Decoder
3 * Copyright (C) 2008 Eli Friedman (eli.friedman@gmail.com)
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 #define BITSTREAM_READER_LE
23 #include "avcodec.h"
24 #include "get_bits.h"
25 #include "internal.h"
26
27 typedef union MacroBlock {
28 uint16_t pixels[4];
29 uint32_t pixels32[2];
30 } MacroBlock;
31
32 typedef union SuperBlock {
33 uint16_t pixels[64];
34 uint32_t pixels32[32];
35 } SuperBlock;
36
37 typedef struct CodeBook {
38 unsigned depth;
39 unsigned size;
40 MacroBlock* blocks;
41 } CodeBook;
42
43 typedef struct Escape124Context {
44 AVFrame *frame;
45
46 unsigned num_superblocks;
47
48 CodeBook codebooks[3];
49 } Escape124Context;
50
51 /**
52 * Initialize the decoder
53 * @param avctx decoder context
54 * @return 0 success, negative on error
55 */
56 2 static av_cold int escape124_decode_init(AVCodecContext *avctx)
57 {
58 2 Escape124Context *s = avctx->priv_data;
59
60 2 avctx->pix_fmt = AV_PIX_FMT_RGB555;
61
62 2 s->num_superblocks = ((unsigned)avctx->width / 8) *
63 2 ((unsigned)avctx->height / 8);
64
65 2 s->frame = av_frame_alloc();
66
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2 if (!s->frame)
67 return AVERROR(ENOMEM);
68
69 2 return 0;
70 }
71
72 2 static av_cold int escape124_decode_close(AVCodecContext *avctx)
73 {
74 unsigned i;
75 2 Escape124Context *s = avctx->priv_data;
76
77
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8 for (i = 0; i < 3; i++)
78 6 av_freep(&s->codebooks[i].blocks);
79
80 2 av_frame_free(&s->frame);
81
82 2 return 0;
83 }
84
85 12 static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
86 unsigned size)
87 {
88 unsigned i, j;
89 12 CodeBook cb = { 0 };
90
91
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12 if (size >= INT_MAX / 34 || get_bits_left(gb) < size * 34)
92 return cb;
93
94
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12 if (size >= INT_MAX / sizeof(MacroBlock))
95 return cb;
96
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12 cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
97
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12 if (!cb.blocks)
98 return cb;
99
100 12 cb.depth = depth;
101 12 cb.size = size;
102
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21255 for (i = 0; i < size; i++) {
103 21243 unsigned mask_bits = get_bits(gb, 4);
104 21243 unsigned color0 = get_bits(gb, 15);
105 21243 unsigned color1 = get_bits(gb, 15);
106
107
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106215 for (j = 0; j < 4; j++) {
108
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84972 if (mask_bits & (1 << j))
109 40481 cb.blocks[i].pixels[j] = color1;
110 else
111 44491 cb.blocks[i].pixels[j] = color0;
112 }
113 }
114 12 return cb;
115 }
116
117 69095 static unsigned decode_skip_count(GetBitContext* gb)
118 {
119 unsigned value;
120 // This function reads a maximum of 23 bits,
121 // which is within the padding space
122
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69095 if (get_bits_left(gb) < 1)
123 return -1;
124 69095 value = get_bits1(gb);
125
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69095 if (!value)
126 59778 return value;
127
128 9317 value += get_bits(gb, 3);
129
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9317 if (value != (1 + ((1 << 3) - 1)))
130 8204 return value;
131
132 1113 value += get_bits(gb, 7);
133
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1113 if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
134 1086 return value;
135
136 27 return value + get_bits(gb, 12);
137 }
138
139 339543 static MacroBlock decode_macroblock(Escape124Context* s, GetBitContext* gb,
140 int* codebook_index, int superblock_index)
141 {
142 // This function reads a maximum of 22 bits; the callers
143 // guard this function appropriately
144 unsigned block_index, depth;
145 339543 int value = get_bits1(gb);
146
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339543 if (value) {
147 static const int8_t transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
148 131966 value = get_bits1(gb);
149 131966 *codebook_index = transitions[*codebook_index][value];
150 }
151
152 339543 depth = s->codebooks[*codebook_index].depth;
153
154 // depth = 0 means that this shouldn't read any bits;
155 // in theory, this is the same as get_bits(gb, 0), but
156 // that doesn't actually work.
157 339543 block_index = get_bitsz(gb, depth);
158
159
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339543 if (*codebook_index == 1) {
160 33088 block_index += superblock_index << s->codebooks[1].depth;
161 }
162
163 // This condition can occur with invalid bitstreams and
164 // *codebook_index == 2
165
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339543 if (block_index >= s->codebooks[*codebook_index].size)
166 return (MacroBlock) { { 0 } };
167
168 339543 return s->codebooks[*codebook_index].blocks[block_index];
169 }
170
171 492736 static void insert_mb_into_sb(SuperBlock* sb, MacroBlock mb, unsigned index) {
172 // Formula: ((index / 4) * 16 + (index % 4) * 2) / 2
173 492736 uint32_t *dst = sb->pixels32 + index + (index & -4);
174
175 // This technically violates C99 aliasing rules, but it should be safe.
176 492736 dst[0] = mb.pixels32[0];
177 492736 dst[4] = mb.pixels32[1];
178 492736 }
179
180 189026 static void copy_superblock(uint16_t* dest, unsigned dest_stride,
181 uint16_t* src, unsigned src_stride)
182 {
183 unsigned y;
184
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189026 if (src)
185
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1690434 for (y = 0; y < 8; y++)
186 1502608 memcpy(dest + y * dest_stride, src + y * src_stride,
187 sizeof(uint16_t) * 8);
188 else
189
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10800 for (y = 0; y < 8; y++)
190 9600 memset(dest + y * dest_stride, 0, sizeof(uint16_t) * 8);
191 189026 }
192
193 static const uint16_t mask_matrix[] = {0x1, 0x2, 0x10, 0x20,
194 0x4, 0x8, 0x40, 0x80,
195 0x100, 0x200, 0x1000, 0x2000,
196 0x400, 0x800, 0x4000, 0x8000};
197
198 100 static int escape124_decode_frame(AVCodecContext *avctx,
199 void *data, int *got_frame,
200 AVPacket *avpkt)
201 {
202 100 int buf_size = avpkt->size;
203 100 Escape124Context *s = avctx->priv_data;
204 100 AVFrame *frame = data;
205
206 GetBitContext gb;
207 unsigned frame_flags, frame_size;
208 unsigned i;
209
210 100 unsigned superblock_index, cb_index = 1,
211 100 superblock_col_index = 0,
212 100 superblocks_per_row = avctx->width / 8, skip = -1;
213
214 uint16_t* old_frame_data, *new_frame_data;
215 unsigned old_stride, new_stride;
216
217 int ret;
218
219
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100 if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
220 return ret;
221
222 // This call also guards the potential depth reads for the
223 // codebook unpacking.
224 // Check if the amount we will read minimally is available on input.
225 // The 64 represent the immediately next 2 frame_* elements read, the 23/4320
226 // represent a lower bound of the space needed for skipped superblocks. Non
227 // skipped SBs need more space.
228
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100 if (get_bits_left(&gb) < 64 + s->num_superblocks * 23LL / 4320)
229 return -1;
230
231 100 frame_flags = get_bits_long(&gb, 32);
232 100 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
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100 if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) {
237 if (!s->frame->data[0])
238 return AVERROR_INVALIDDATA;
239
240 av_log(avctx, 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
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400 for (i = 0; i < 3; i++) {
250
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300 if (frame_flags & (1 << (17 + i))) {
251 unsigned cb_depth, cb_size;
252
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12 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 4 cb_size = get_bits(&gb, 20);
256
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4 if (!cb_size) {
257 av_log(avctx, AV_LOG_ERROR, "Invalid codebook size 0.\n");
258 return AVERROR_INVALIDDATA;
259 }
260 4 cb_depth = av_log2(cb_size - 1) + 1;
261 } else {
262 8 cb_depth = get_bits(&gb, 4);
263
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8 if (i == 0) {
264 // This is the most basic codebook: pow(2,depth) entries
265 // for a depth-length key
266 4 cb_size = 1 << cb_depth;
267 } else {
268 // This codebook varies per superblock
269 // FIXME: I don't think this handles integer overflow
270 // properly
271 4 cb_size = s->num_superblocks << cb_depth;
272 }
273 }
274
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12 if (s->num_superblocks >= INT_MAX >> cb_depth) {
275 av_log(avctx, AV_LOG_ERROR, "Depth or num_superblocks are too large\n");
276 return AVERROR_INVALIDDATA;
277 }
278
279 12 av_freep(&s->codebooks[i].blocks);
280 12 s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
281
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12 if (!s->codebooks[i].blocks)
282 return -1;
283 }
284 }
285
286
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100 if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
287 return ret;
288
289 100 new_frame_data = (uint16_t*)frame->data[0];
290 100 new_stride = frame->linesize[0] / 2;
291 100 old_frame_data = (uint16_t*)s->frame->data[0];
292 100 old_stride = s->frame->linesize[0] / 2;
293
294
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120100 for (superblock_index = 0; superblock_index < s->num_superblocks;
295 120000 superblock_index++) {
296 MacroBlock mb;
297 SuperBlock sb;
298 120000 unsigned multi_mask = 0;
299
300
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120000 if (skip == -1) {
301 // Note that this call will make us skip the rest of the blocks
302 // if the frame prematurely ends
303 69095 skip = decode_skip_count(&gb);
304 }
305
306
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120000 if (skip) {
307 50974 copy_superblock(new_frame_data, new_stride,
308 old_frame_data, old_stride);
309 } else {
310 69026 copy_superblock(sb.pixels, 8,
311 old_frame_data, old_stride);
312
313
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100930 while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
314 unsigned mask;
315 31904 mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
316 31904 mask = get_bits(&gb, 16);
317 31904 multi_mask |= mask;
318
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542368 for (i = 0; i < 16; i++) {
319
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510464 if (mask & mask_matrix[i]) {
320 185097 insert_mb_into_sb(&sb, mb, i);
321 }
322 }
323 }
324
325
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69026 if (!get_bits1(&gb)) {
326 29605 unsigned inv_mask = get_bits(&gb, 4);
327
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148025 for (i = 0; i < 4; i++) {
328
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118420 if (inv_mask & (1 << i)) {
329 45362 multi_mask ^= 0xF << i*4;
330 } else {
331 73058 multi_mask ^= get_bits(&gb, 4) << i*4;
332 }
333 }
334
335
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503285 for (i = 0; i < 16; i++) {
336
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473680 if (multi_mask & mask_matrix[i]) {
337 251422 mb = decode_macroblock(s, &gb, &cb_index,
338 superblock_index);
339 251422 insert_mb_into_sb(&sb, mb, i);
340 }
341 }
342
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39421 } else if (frame_flags & (1 << 16)) {
343
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95638 while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
344 56217 mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
345 56217 insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
346 }
347 }
348
349 69026 copy_superblock(new_frame_data, new_stride, sb.pixels, 8);
350 }
351
352 120000 superblock_col_index++;
353 120000 new_frame_data += 8;
354
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120000 if (old_frame_data)
355 118800 old_frame_data += 8;
356
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120000 if (superblock_col_index == superblocks_per_row) {
357 3000 new_frame_data += new_stride * 8 - superblocks_per_row * 8;
358
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3000 if (old_frame_data)
359 2970 old_frame_data += old_stride * 8 - superblocks_per_row * 8;
360 3000 superblock_col_index = 0;
361 }
362 120000 skip--;
363 }
364
365 100 av_log(avctx, AV_LOG_DEBUG,
366 "Escape sizes: %i, %i, %i\n",
367 100 frame_size, buf_size, get_bits_count(&gb) / 8);
368
369 100 av_frame_unref(s->frame);
370
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100 if ((ret = av_frame_ref(s->frame, frame)) < 0)
371 return ret;
372
373 100 *got_frame = 1;
374
375 100 return frame_size;
376 }
377
378
379 const AVCodec ff_escape124_decoder = {
380 .name = "escape124",
381 .long_name = NULL_IF_CONFIG_SMALL("Escape 124"),
382 .type = AVMEDIA_TYPE_VIDEO,
383 .id = AV_CODEC_ID_ESCAPE124,
384 .priv_data_size = sizeof(Escape124Context),
385 .init = escape124_decode_init,
386 .close = escape124_decode_close,
387 .decode = escape124_decode_frame,
388 .capabilities = AV_CODEC_CAP_DR1,
389 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
390 };
391