FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/escape124.c
Date: 2022-07-04 19:11:22
Exec Total Coverage
Lines: 142 164 86.6%
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 "codec_internal.h"
25 #include "get_bits.h"
26 #include "internal.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 /**
53 * Initialize the decoder
54 * @param avctx decoder context
55 * @return 0 success, negative on error
56 */
57 2 static av_cold int escape124_decode_init(AVCodecContext *avctx)
58 {
59 2 Escape124Context *s = avctx->priv_data;
60
61 2 avctx->pix_fmt = AV_PIX_FMT_RGB555;
62
63 2 s->num_superblocks = ((unsigned)avctx->width / 8) *
64 2 ((unsigned)avctx->height / 8);
65
66 2 s->frame = av_frame_alloc();
67
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2 if (!s->frame)
68 return AVERROR(ENOMEM);
69
70 2 return 0;
71 }
72
73 2 static av_cold int escape124_decode_close(AVCodecContext *avctx)
74 {
75 unsigned i;
76 2 Escape124Context *s = avctx->priv_data;
77
78
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8 for (i = 0; i < 3; i++)
79 6 av_freep(&s->codebooks[i].blocks);
80
81 2 av_frame_free(&s->frame);
82
83 2 return 0;
84 }
85
86 12 static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
87 unsigned size)
88 {
89 unsigned i, j;
90 12 CodeBook cb = { 0 };
91
92
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12 if (size >= INT_MAX / 34 || get_bits_left(gb) < size * 34)
93 return cb;
94
95
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12 if (size >= INT_MAX / sizeof(MacroBlock))
96 return cb;
97
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12 cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
98
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12 if (!cb.blocks)
99 return cb;
100
101 12 cb.depth = depth;
102 12 cb.size = size;
103
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21255 for (i = 0; i < size; i++) {
104 21243 unsigned mask_bits = get_bits(gb, 4);
105 21243 unsigned color0 = get_bits(gb, 15);
106 21243 unsigned color1 = get_bits(gb, 15);
107
108
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106215 for (j = 0; j < 4; j++) {
109
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84972 if (mask_bits & (1 << j))
110 40481 cb.blocks[i].pixels[j] = color1;
111 else
112 44491 cb.blocks[i].pixels[j] = color0;
113 }
114 }
115 12 return cb;
116 }
117
118 69095 static unsigned decode_skip_count(GetBitContext* gb)
119 {
120 unsigned value;
121 // This function reads a maximum of 23 bits,
122 // which is within the padding space
123
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69095 if (get_bits_left(gb) < 1)
124 return -1;
125 69095 value = get_bits1(gb);
126
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69095 if (!value)
127 59778 return value;
128
129 9317 value += get_bits(gb, 3);
130
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9317 if (value != (1 + ((1 << 3) - 1)))
131 8204 return value;
132
133 1113 value += get_bits(gb, 7);
134
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1113 if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
135 1086 return value;
136
137 27 return value + get_bits(gb, 12);
138 }
139
140 339543 static MacroBlock decode_macroblock(Escape124Context* s, GetBitContext* gb,
141 int* codebook_index, int superblock_index)
142 {
143 // This function reads a maximum of 22 bits; the callers
144 // guard this function appropriately
145 unsigned block_index, depth;
146 339543 int value = get_bits1(gb);
147
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339543 if (value) {
148 static const int8_t transitions[3][2] = { {2, 1}, {0, 2}, {1, 0} };
149 131966 value = get_bits1(gb);
150 131966 *codebook_index = transitions[*codebook_index][value];
151 }
152
153 339543 depth = s->codebooks[*codebook_index].depth;
154
155 // depth = 0 means that this shouldn't read any bits;
156 // in theory, this is the same as get_bits(gb, 0), but
157 // that doesn't actually work.
158 339543 block_index = get_bitsz(gb, depth);
159
160
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339543 if (*codebook_index == 1) {
161 33088 block_index += superblock_index << s->codebooks[1].depth;
162 }
163
164 // This condition can occur with invalid bitstreams and
165 // *codebook_index == 2
166
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339543 if (block_index >= s->codebooks[*codebook_index].size)
167 return (MacroBlock) { { 0 } };
168
169 339543 return s->codebooks[*codebook_index].blocks[block_index];
170 }
171
172 492736 static void insert_mb_into_sb(SuperBlock* sb, MacroBlock mb, unsigned index) {
173 // Formula: ((index / 4) * 16 + (index % 4) * 2) / 2
174 492736 uint32_t *dst = sb->pixels32 + index + (index & -4);
175
176 // This technically violates C99 aliasing rules, but it should be safe.
177 492736 dst[0] = mb.pixels32[0];
178 492736 dst[4] = mb.pixels32[1];
179 492736 }
180
181 189026 static void copy_superblock(uint16_t* dest, unsigned dest_stride,
182 uint16_t* src, unsigned src_stride)
183 {
184 unsigned y;
185
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189026 if (src)
186
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1690434 for (y = 0; y < 8; y++)
187 1502608 memcpy(dest + y * dest_stride, src + y * src_stride,
188 sizeof(uint16_t) * 8);
189 else
190
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10800 for (y = 0; y < 8; y++)
191 9600 memset(dest + y * dest_stride, 0, sizeof(uint16_t) * 8);
192 189026 }
193
194 static const uint16_t mask_matrix[] = {0x1, 0x2, 0x10, 0x20,
195 0x4, 0x8, 0x40, 0x80,
196 0x100, 0x200, 0x1000, 0x2000,
197 0x400, 0x800, 0x4000, 0x8000};
198
199 100 static int escape124_decode_frame(AVCodecContext *avctx, AVFrame *frame,
200 int *got_frame, AVPacket *avpkt)
201 {
202 100 int buf_size = avpkt->size;
203 100 Escape124Context *s = avctx->priv_data;
204
205 GetBitContext gb;
206 unsigned frame_flags, frame_size;
207 unsigned i;
208
209 100 unsigned superblock_index, cb_index = 1,
210 100 superblock_col_index = 0,
211 100 superblocks_per_row = avctx->width / 8, skip = -1;
212
213 uint16_t* old_frame_data, *new_frame_data;
214 unsigned old_stride, new_stride;
215
216 int ret;
217
218
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100 if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
219 return ret;
220
221 // This call also guards the potential depth reads for the
222 // codebook unpacking.
223 // Check if the amount we will read minimally is available on input.
224 // The 64 represent the immediately next 2 frame_* elements read, the 23/4320
225 // represent a lower bound of the space needed for skipped superblocks. Non
226 // skipped SBs need more space.
227
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100 if (get_bits_left(&gb) < 64 + s->num_superblocks * 23LL / 4320)
228 return -1;
229
230 100 frame_flags = get_bits_long(&gb, 32);
231 100 frame_size = get_bits_long(&gb, 32);
232
233 // Leave last frame unchanged
234 // FIXME: Is this necessary? I haven't seen it in any real samples
235
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100 if (!(frame_flags & 0x114) || !(frame_flags & 0x7800000)) {
236 if (!s->frame->data[0])
237 return AVERROR_INVALIDDATA;
238
239 av_log(avctx, AV_LOG_DEBUG, "Skipping frame\n");
240
241 *got_frame = 1;
242 if ((ret = av_frame_ref(frame, s->frame)) < 0)
243 return ret;
244
245 return frame_size;
246 }
247
248
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400 for (i = 0; i < 3; i++) {
249
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300 if (frame_flags & (1 << (17 + i))) {
250 unsigned cb_depth, cb_size;
251
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12 if (i == 2) {
252 // This codebook can be cut off at places other than
253 // powers of 2, leaving some of the entries undefined.
254 4 cb_size = get_bits(&gb, 20);
255
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4 if (!cb_size) {
256 av_log(avctx, AV_LOG_ERROR, "Invalid codebook size 0.\n");
257 return AVERROR_INVALIDDATA;
258 }
259 4 cb_depth = av_log2(cb_size - 1) + 1;
260 } else {
261 8 cb_depth = get_bits(&gb, 4);
262
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8 if (i == 0) {
263 // This is the most basic codebook: pow(2,depth) entries
264 // for a depth-length key
265 4 cb_size = 1 << cb_depth;
266 } else {
267 // This codebook varies per superblock
268 // FIXME: I don't think this handles integer overflow
269 // properly
270 4 cb_size = s->num_superblocks << cb_depth;
271 }
272 }
273
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12 if (s->num_superblocks >= INT_MAX >> cb_depth) {
274 av_log(avctx, AV_LOG_ERROR, "Depth or num_superblocks are too large\n");
275 return AVERROR_INVALIDDATA;
276 }
277
278 12 av_freep(&s->codebooks[i].blocks);
279 12 s->codebooks[i] = unpack_codebook(&gb, cb_depth, cb_size);
280
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12 if (!s->codebooks[i].blocks)
281 return -1;
282 }
283 }
284
285
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100 if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
286 return ret;
287
288 100 new_frame_data = (uint16_t*)frame->data[0];
289 100 new_stride = frame->linesize[0] / 2;
290 100 old_frame_data = (uint16_t*)s->frame->data[0];
291 100 old_stride = s->frame->linesize[0] / 2;
292
293
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120100 for (superblock_index = 0; superblock_index < s->num_superblocks;
294 120000 superblock_index++) {
295 MacroBlock mb;
296 SuperBlock sb;
297 120000 unsigned multi_mask = 0;
298
299
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120000 if (skip == -1) {
300 // Note that this call will make us skip the rest of the blocks
301 // if the frame prematurely ends
302 69095 skip = decode_skip_count(&gb);
303 }
304
305
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120000 if (skip) {
306 50974 copy_superblock(new_frame_data, new_stride,
307 old_frame_data, old_stride);
308 } else {
309 69026 copy_superblock(sb.pixels, 8,
310 old_frame_data, old_stride);
311
312
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100930 while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
313 unsigned mask;
314 31904 mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
315 31904 mask = get_bits(&gb, 16);
316 31904 multi_mask |= mask;
317
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542368 for (i = 0; i < 16; i++) {
318
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510464 if (mask & mask_matrix[i]) {
319 185097 insert_mb_into_sb(&sb, mb, i);
320 }
321 }
322 }
323
324
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69026 if (!get_bits1(&gb)) {
325 29605 unsigned inv_mask = get_bits(&gb, 4);
326
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148025 for (i = 0; i < 4; i++) {
327
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118420 if (inv_mask & (1 << i)) {
328 45362 multi_mask ^= 0xF << i*4;
329 } else {
330 73058 multi_mask ^= get_bits(&gb, 4) << i*4;
331 }
332 }
333
334
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503285 for (i = 0; i < 16; i++) {
335
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473680 if (multi_mask & mask_matrix[i]) {
336 251422 mb = decode_macroblock(s, &gb, &cb_index,
337 superblock_index);
338 251422 insert_mb_into_sb(&sb, mb, i);
339 }
340 }
341
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39421 } else if (frame_flags & (1 << 16)) {
342
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95638 while (get_bits_left(&gb) >= 1 && !get_bits1(&gb)) {
343 56217 mb = decode_macroblock(s, &gb, &cb_index, superblock_index);
344 56217 insert_mb_into_sb(&sb, mb, get_bits(&gb, 4));
345 }
346 }
347
348 69026 copy_superblock(new_frame_data, new_stride, sb.pixels, 8);
349 }
350
351 120000 superblock_col_index++;
352 120000 new_frame_data += 8;
353
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120000 if (old_frame_data)
354 118800 old_frame_data += 8;
355
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120000 if (superblock_col_index == superblocks_per_row) {
356 3000 new_frame_data += new_stride * 8 - superblocks_per_row * 8;
357
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3000 if (old_frame_data)
358 2970 old_frame_data += old_stride * 8 - superblocks_per_row * 8;
359 3000 superblock_col_index = 0;
360 }
361 120000 skip--;
362 }
363
364 100 av_log(avctx, AV_LOG_DEBUG,
365 "Escape sizes: %i, %i, %i\n",
366 100 frame_size, buf_size, get_bits_count(&gb) / 8);
367
368 100 av_frame_unref(s->frame);
369
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100 if ((ret = av_frame_ref(s->frame, frame)) < 0)
370 return ret;
371
372 100 *got_frame = 1;
373
374 100 return frame_size;
375 }
376
377
378 const FFCodec ff_escape124_decoder = {
379 .p.name = "escape124",
380 .p.long_name = NULL_IF_CONFIG_SMALL("Escape 124"),
381 .p.type = AVMEDIA_TYPE_VIDEO,
382 .p.id = AV_CODEC_ID_ESCAPE124,
383 .priv_data_size = sizeof(Escape124Context),
384 .init = escape124_decode_init,
385 .close = escape124_decode_close,
386 FF_CODEC_DECODE_CB(escape124_decode_frame),
387 .p.capabilities = AV_CODEC_CAP_DR1,
388 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
389 };
390