GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavcodec/escape124.c Lines: 143 165 86.7 %
Date: 2019-11-22 03:34:36 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
 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * 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
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
8
    for (i = 0; i < 3; i++)
78
6
        av_freep(&s->codebooks[i].blocks);
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80
2
    av_frame_free(&s->frame);
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82
2
    return 0;
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}
84
85
12
static CodeBook unpack_codebook(GetBitContext* gb, unsigned depth,
86
                                 unsigned size)
87
{
88
    unsigned i, j;
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12
    CodeBook cb = { 0 };
90
91

12
    if (size >= INT_MAX / 34 || get_bits_left(gb) < size * 34)
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        return cb;
93
94
12
    if (size >= INT_MAX / sizeof(MacroBlock))
95
        return cb;
96
12
    cb.blocks = av_malloc(size ? size * sizeof(MacroBlock) : 1);
97
12
    if (!cb.blocks)
98
        return cb;
99
100
12
    cb.depth = depth;
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12
    cb.size = size;
102
21255
    for (i = 0; i < size; i++) {
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21243
        unsigned mask_bits = get_bits(gb, 4);
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21243
        unsigned color0 = get_bits(gb, 15);
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21243
        unsigned color1 = get_bits(gb, 15);
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107
106215
        for (j = 0; j < 4; j++) {
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84972
            if (mask_bits & (1 << j))
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40481
                cb.blocks[i].pixels[j] = color1;
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            else
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44491
                cb.blocks[i].pixels[j] = color0;
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        }
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    }
114
12
    return cb;
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}
116
117
69095
static unsigned decode_skip_count(GetBitContext* gb)
118
{
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    unsigned value;
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    // This function reads a maximum of 23 bits,
121
    // which is within the padding space
122
69095
    if (get_bits_left(gb) < 1)
123
        return -1;
124
69095
    value = get_bits1(gb);
125
69095
    if (!value)
126
59778
        return value;
127
128
9317
    value += get_bits(gb, 3);
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9317
    if (value != (1 + ((1 << 3) - 1)))
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8204
        return value;
131
132
1113
    value += get_bits(gb, 7);
133
1113
    if (value != (1 + ((1 << 3) - 1)) + ((1 << 7) - 1))
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1086
        return value;
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136
27
    return value + get_bits(gb, 12);
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}
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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
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
339543
    if (*codebook_index == 1) {
160
33088
        block_index += superblock_index << s->codebooks[1].depth;
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    }
162
163
    // This condition can occur with invalid bitstreams and
164
    // *codebook_index == 2
165
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
189026
    if (src)
185
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
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
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
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

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
400
    for (i = 0; i < 3; i++) {
250
300
        if (frame_flags & (1 << (17 + i))) {
251
            unsigned cb_depth, cb_size;
252
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_long(&gb, 20);
256
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
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
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
12
            if (!s->codebooks[i].blocks)
282
                return -1;
283
        }
284
    }
285
286
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
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
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
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

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
542368
                for (i = 0; i < 16; i++) {
319
510464
                    if (mask & mask_matrix[i]) {
320
185097
                        insert_mb_into_sb(&sb, mb, i);
321
                    }
322
                }
323
            }
324
325
69026
            if (!get_bits1(&gb)) {
326
29605
                unsigned inv_mask = get_bits(&gb, 4);
327
148025
                for (i = 0; i < 4; i++) {
328
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
503285
                for (i = 0; i < 16; i++) {
336
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
39421
            } else if (frame_flags & (1 << 16)) {
343

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
120000
        if (old_frame_data)
355
118800
            old_frame_data += 8;
356
120000
        if (superblock_col_index == superblocks_per_row) {
357
3000
            new_frame_data += new_stride * 8 - superblocks_per_row * 8;
358
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
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
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
};