GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavcodec/mss4.c Lines: 270 298 90.6 %
Date: 2021-04-20 15:25:36 Branches: 159 186 85.5 %

Line Branch Exec Source
1
/*
2
 * Microsoft Screen 4 (aka Microsoft Expression Encoder Screen) decoder
3
 * Copyright (c) 2012 Konstantin Shishkov
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
/**
23
 * @file
24
 * Microsoft Screen 4 (aka Microsoft Titanium Screen 2,
25
 * aka Microsoft Expression Encoder Screen) decoder
26
 */
27
28
#include "libavutil/thread.h"
29
30
#include "avcodec.h"
31
#include "bytestream.h"
32
#include "get_bits.h"
33
#include "internal.h"
34
#include "jpegtables.h"
35
#include "mss34dsp.h"
36
#include "unary.h"
37
38
#define HEADER_SIZE 8
39
40
enum FrameType {
41
    INTRA_FRAME = 0,
42
    INTER_FRAME,
43
    SKIP_FRAME
44
};
45
46
enum BlockType {
47
    SKIP_BLOCK = 0,
48
    DCT_BLOCK,
49
    IMAGE_BLOCK,
50
};
51
52
enum CachePos {
53
    LEFT = 0,
54
    TOP_LEFT,
55
    TOP,
56
};
57
58
static const uint8_t mss4_dc_vlc_lens[2][16] = {
59
    { 0, 1, 5, 1, 1, 1, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0 },
60
    { 0, 3, 1, 1, 1, 1, 1, 1, 1, 2, 0, 0, 0, 0, 0, 0 }
61
};
62
63
static const uint8_t vec_len_syms[2][4] = {
64
    { 4, 2, 3, 1 },
65
    { 4, 1, 2, 3 }
66
};
67
68
static const uint8_t mss4_vec_entry_vlc_lens[2][16] = {
69
    { 0, 2, 2, 3, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
70
    { 0, 1, 5, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
71
};
72
73
static const uint8_t mss4_vec_entry_vlc_syms[2][9] = {
74
    { 0, 7, 6, 5, 8, 4, 3, 1, 2 },
75
    { 0, 2, 3, 4, 5, 6, 7, 1, 8 }
76
};
77
78
#define MAX_ENTRIES  162
79
80
typedef struct MSS4Context {
81
    AVFrame    *pic;
82
83
    int        block[64];
84
    uint8_t    imgbuf[3][16 * 16];
85
86
    int        quality;
87
    uint16_t   quant_mat[2][64];
88
89
    int        *prev_dc[3];
90
    ptrdiff_t  dc_stride[3];
91
    int        dc_cache[4][4];
92
93
    int        prev_vec[3][4];
94
} MSS4Context;
95
96
static VLC dc_vlc[2], ac_vlc[2];
97
static VLC vec_entry_vlc[2];
98
99
12
static av_cold void mss4_init_vlc(VLC *vlc, unsigned *offset,
100
                                  const uint8_t *lens, const uint8_t *syms)
101
{
102
    static VLC_TYPE vlc_buf[2146][2];
103
    uint8_t  bits[MAX_ENTRIES];
104
    int i, j;
105
12
    int idx = 0;
106
107
204
    for (i = 0; i < 16; i++) {
108
924
        for (j = 0; j < lens[i]; j++) {
109
732
            bits[idx]  = i + 1;
110
732
            idx++;
111
        }
112
    }
113
114
12
    vlc->table           = &vlc_buf[*offset];
115
12
    vlc->table_allocated = FF_ARRAY_ELEMS(vlc_buf) - *offset;
116
12
    ff_init_vlc_from_lengths(vlc, FFMIN(bits[idx - 1], 9), idx,
117
                             bits, 1, syms, 1, 1,
118
                             0, INIT_VLC_STATIC_OVERLONG, NULL);
119
12
    *offset += vlc->table_size;
120
12
}
121
122
2
static av_cold void mss4_init_vlcs(void)
123
{
124
6
    for (unsigned i = 0, offset = 0; i < 2; i++) {
125
4
        mss4_init_vlc(&dc_vlc[i], &offset, mss4_dc_vlc_lens[i], NULL);
126

4
        mss4_init_vlc(&ac_vlc[i], &offset,
127
                      i ? avpriv_mjpeg_bits_ac_chrominance + 1
128
                        : avpriv_mjpeg_bits_ac_luminance   + 1,
129
                      i ? avpriv_mjpeg_val_ac_chrominance
130
                        : avpriv_mjpeg_val_ac_luminance);
131
4
        mss4_init_vlc(&vec_entry_vlc[i], &offset, mss4_vec_entry_vlc_lens[i],
132
4
                      mss4_vec_entry_vlc_syms[i]);
133
    }
134
2
}
135
136
/* This function returns values in the range
137
 * (-range + 1; -range/2] U [range/2; range - 1)
138
 * i.e.
139
 * nbits = 0 -> 0
140
 * nbits = 1 -> -1, 1
141
 * nbits = 2 -> -3, -2, 2, 3
142
 */
143
315916
static av_always_inline int get_coeff_bits(GetBitContext *gb, int nbits)
144
{
145
    int val;
146
147
315916
    if (!nbits)
148
133329
        return 0;
149
150
182587
    val = get_bits(gb, nbits);
151
182587
    if (val < (1 << (nbits - 1)))
152
98069
        val -= (1 << nbits) - 1;
153
154
182587
    return val;
155
}
156
157
180586
static inline int get_coeff(GetBitContext *gb, VLC *vlc)
158
{
159
180586
    int val = get_vlc2(gb, vlc->table, vlc->bits, 2);
160
161
180586
    return get_coeff_bits(gb, val);
162
}
163
164
85284
static int mss4_decode_dct(GetBitContext *gb, VLC *dc_vlc, VLC *ac_vlc,
165
                           int *block, int *dc_cache,
166
                           int bx, int by, uint16_t *quant_mat)
167
{
168
85284
    int skip, val, pos = 1, zz_pos, dc;
169
170
85284
    memset(block, 0, sizeof(*block) * 64);
171
172
85284
    dc = get_coeff(gb, dc_vlc);
173
    // DC prediction is the same as in MSS3
174
85284
    if (by) {
175
84904
        if (bx) {
176
            int l, tl, t;
177
178
83868
            l  = dc_cache[LEFT];
179
83868
            tl = dc_cache[TOP_LEFT];
180
83868
            t  = dc_cache[TOP];
181
182
83868
            if (FFABS(t - tl) <= FFABS(l - tl))
183
80876
                dc += l;
184
            else
185
2992
                dc += t;
186
        } else {
187
1036
            dc += dc_cache[TOP];
188
        }
189
380
    } else if (bx) {
190
380
        dc += dc_cache[LEFT];
191
    }
192
85284
    dc_cache[LEFT] = dc;
193
85284
    block[0]       = dc * quant_mat[0];
194
195
220682
    while (pos < 64) {
196
219785
        val = get_vlc2(gb, ac_vlc->table, 9, 2);
197
219785
        if (!val)
198
84387
            return 0;
199
135398
        if (val == -1)
200
            return -1;
201
135398
        if (val == 0xF0) {
202
68
            pos += 16;
203
68
            continue;
204
        }
205
135330
        skip = val >> 4;
206
135330
        val  = get_coeff_bits(gb, val & 0xF);
207
135330
        pos += skip;
208
135330
        if (pos >= 64)
209
            return -1;
210
211
135330
        zz_pos = ff_zigzag_direct[pos];
212
135330
        block[zz_pos] = val * quant_mat[zz_pos];
213
135330
        pos++;
214
    }
215
216
897
    return pos == 64 ? 0 : -1;
217
}
218
219
14214
static int mss4_decode_dct_block(MSS4Context *c, GetBitContext *gb,
220
                                 uint8_t *dst[3], int mb_x, int mb_y)
221
{
222
    int i, j, k, ret;
223
14214
    uint8_t *out = dst[0];
224
225
42642
    for (j = 0; j < 2; j++) {
226
85284
        for (i = 0; i < 2; i++) {
227
56856
            int xpos = mb_x * 2 + i;
228
56856
            c->dc_cache[j][TOP_LEFT] = c->dc_cache[j][TOP];
229
56856
            c->dc_cache[j][TOP]      = c->prev_dc[0][mb_x * 2 + i];
230
56856
            ret = mss4_decode_dct(gb, &dc_vlc[0], &ac_vlc[0], c->block,
231
56856
                                  c->dc_cache[j],
232
56856
                                  xpos, mb_y * 2 + j, c->quant_mat[0]);
233
56856
            if (ret)
234
                return ret;
235
56856
            c->prev_dc[0][mb_x * 2 + i] = c->dc_cache[j][LEFT];
236
237
56856
            ff_mss34_dct_put(out + xpos * 8, c->pic->linesize[0],
238
56856
                             c->block);
239
        }
240
28428
        out += 8 * c->pic->linesize[0];
241
    }
242
243
42642
    for (i = 1; i < 3; i++) {
244
28428
        c->dc_cache[i + 1][TOP_LEFT] = c->dc_cache[i + 1][TOP];
245
28428
        c->dc_cache[i + 1][TOP]      = c->prev_dc[i][mb_x];
246
28428
        ret = mss4_decode_dct(gb, &dc_vlc[1], &ac_vlc[1],
247
28428
                              c->block, c->dc_cache[i + 1], mb_x, mb_y,
248
28428
                              c->quant_mat[1]);
249
28428
        if (ret)
250
            return ret;
251
28428
        c->prev_dc[i][mb_x] = c->dc_cache[i + 1][LEFT];
252
253
28428
        ff_mss34_dct_put(c->imgbuf[i], 8, c->block);
254
28428
        out = dst[i] + mb_x * 16;
255
        // Since the DCT block is coded as YUV420 and the whole frame as YUV444,
256
        // we need to scale chroma.
257
483276
        for (j = 0; j < 16; j++) {
258
4093632
            for (k = 0; k < 8; k++)
259
3638784
                AV_WN16A(out + k * 2, c->imgbuf[i][k + (j & ~1) * 4] * 0x101);
260
454848
            out += c->pic->linesize[i];
261
        }
262
    }
263
264
14214
    return 0;
265
}
266
267
281245
static void read_vec_pos(GetBitContext *gb, int *vec_pos, int *sel_flag,
268
                         int *sel_len, int *prev)
269
{
270
281245
    int i, y_flag = 0;
271
272
1124980
    for (i = 2; i >= 0; i--) {
273
843735
        if (!sel_flag[i]) {
274
192630
            vec_pos[i] = 0;
275
192630
            continue;
276
        }
277

651105
        if ((!i && !y_flag) || get_bits1(gb)) {
278
554066
            if (sel_len[i] > 0) {
279
549560
                int pval = prev[i];
280
549560
                vec_pos[i] = get_bits(gb, sel_len[i]);
281
549560
                if (vec_pos[i] >= pval)
282
297455
                    vec_pos[i]++;
283
            } else {
284
4506
                vec_pos[i] = !prev[i];
285
            }
286
554066
            y_flag = 1;
287
        } else {
288
97039
            vec_pos[i] = prev[i];
289
        }
290
    }
291
281245
}
292
293
8739072
static int get_value_cached(GetBitContext *gb, int vec_pos, uint8_t *vec,
294
                            int vec_size, int component, int shift, int *prev)
295
{
296
8739072
    if (vec_pos < vec_size)
297
8442194
        return vec[vec_pos];
298
296878
    if (!get_bits1(gb))
299
46525
        return prev[component];
300
250353
    prev[component] = get_bits(gb, 8 - shift) << shift;
301
250353
    return prev[component];
302
}
303
304
#define MKVAL(vals)  ((vals)[0] | ((vals)[1] << 3) | ((vals)[2] << 6))
305
306
/* Image mode - the hardest to comprehend MSS4 coding mode.
307
 *
308
 * In this mode all three 16x16 blocks are coded together with a method
309
 * remotely similar to the methods employed in MSS1-MSS3.
310
 * The idea is that every component has a vector of 1-4 most common symbols
311
 * and an escape mode for reading new value from the bitstream. Decoding
312
 * consists of retrieving pixel values from the vector or reading new ones
313
 * from the bitstream; depending on flags read from the bitstream, these vector
314
 * positions can be updated or reused from the state of the previous line
315
 * or previous pixel.
316
 */
317
11379
static int mss4_decode_image_block(MSS4Context *ctx, GetBitContext *gb,
318
                                   uint8_t *picdst[3], int mb_x, int mb_y)
319
{
320
    uint8_t vec[3][4];
321
    int     vec_len[3];
322
    int     sel_len[3], sel_flag[3];
323
    int     i, j, k, mode, split;
324
11379
    int     prev_vec1 = 0, prev_split = 0;
325
11379
    int     vals[3] = { 0 };
326
11379
    int     prev_pix[3] = { 0 };
327
11379
    int     prev_mode[16] = { 0 };
328
    uint8_t *dst[3];
329
330
11379
    const int val_shift = ctx->quality == 100 ? 0 : 2;
331
332
45516
    for (i = 0; i < 3; i++)
333
34137
        dst[i] = ctx->imgbuf[i];
334
335
45516
    for (i = 0; i < 3; i++) {
336
34137
        vec_len[i] = vec_len_syms[!!i][get_unary(gb, 0, 3)];
337
129439
        for (j = 0; j < vec_len[i]; j++) {
338
95302
            vec[i][j]  = get_coeff(gb, &vec_entry_vlc[!!i]);
339
95302
            vec[i][j] += ctx->prev_vec[i][j];
340
95302
            ctx->prev_vec[i][j] = vec[i][j];
341
        }
342
34137
        sel_flag[i] = vec_len[i] > 1;
343
34137
        sel_len[i]  = vec_len[i] > 2 ? vec_len[i] - 2 : 0;
344
    }
345
346
193443
    for (j = 0; j < 16; j++) {
347
182064
        if (get_bits1(gb)) {
348
56004
            split = 0;
349
56004
            if (get_bits1(gb)) {
350
35860
                prev_mode[0] = 0;
351
35860
                vals[0] = vals[1] = vals[2] = 0;
352
35860
                mode = 2;
353
            } else {
354
20144
                mode = get_bits1(gb);
355
20144
                if (mode)
356
3817
                    split = get_bits(gb, 4);
357
            }
358
952068
            for (i = 0; i < 16; i++) {
359
896064
                if (mode <= 1) {
360
322304
                    vals[0] =  prev_mode[i]       & 7;
361
322304
                    vals[1] = (prev_mode[i] >> 3) & 7;
362
322304
                    vals[2] =  prev_mode[i] >> 6;
363

322304
                    if (mode == 1 && i == split) {
364
3817
                        read_vec_pos(gb, vals, sel_flag, sel_len, vals);
365
                    }
366
573760
                } else if (mode == 2) {
367
573760
                    if (get_bits1(gb))
368
261389
                        read_vec_pos(gb, vals, sel_flag, sel_len, vals);
369
                }
370
3584256
                for (k = 0; k < 3; k++)
371
2688192
                    *dst[k]++ = get_value_cached(gb, vals[k], vec[k],
372
                                                 vec_len[k], k,
373
                                                 val_shift, prev_pix);
374
896064
                prev_mode[i] = MKVAL(vals);
375
            }
376
        } else {
377
126060
            if (get_bits1(gb)) {
378
21425
                split = get_bits(gb, 4);
379
21425
                if (split >= prev_split)
380
15525
                    split++;
381
21425
                prev_split = split;
382
            } else {
383
104635
                split = prev_split;
384
            }
385
126060
            if (split) {
386
109261
                vals[0] =  prev_mode[0]       & 7;
387
109261
                vals[1] = (prev_mode[0] >> 3) & 7;
388
109261
                vals[2] =  prev_mode[0] >> 6;
389
437044
                for (i = 0; i < 3; i++) {
390
5442705
                    for (k = 0; k < split; k++) {
391
5114922
                        *dst[i]++ = get_value_cached(gb, vals[i], vec[i],
392
                                                     vec_len[i], i, val_shift,
393
                                                     prev_pix);
394
5114922
                        prev_mode[k] = MKVAL(vals);
395
                    }
396
                }
397
            }
398
399
126060
            if (split != 16) {
400
22314
                vals[0] =  prev_vec1       & 7;
401
22314
                vals[1] = (prev_vec1 >> 3) & 7;
402
22314
                vals[2] =  prev_vec1 >> 6;
403
22314
                if (get_bits1(gb)) {
404
16039
                    read_vec_pos(gb, vals, sel_flag, sel_len, vals);
405
16039
                    prev_vec1 = MKVAL(vals);
406
                }
407
89256
                for (i = 0; i < 3; i++) {
408
1002900
                    for (k = 0; k < 16 - split; k++) {
409
935958
                        *dst[i]++ = get_value_cached(gb, vals[i], vec[i],
410
                                                     vec_len[i], i, val_shift,
411
                                                     prev_pix);
412
935958
                        prev_mode[split + k] = MKVAL(vals);
413
                    }
414
                }
415
            }
416
        }
417
    }
418
419
45516
    for (i = 0; i < 3; i++)
420
580329
        for (j = 0; j < 16; j++)
421
546192
            memcpy(picdst[i] + mb_x * 16 + j * ctx->pic->linesize[i],
422
546192
                   ctx->imgbuf[i] + j * 16, 16);
423
424
11379
    return 0;
425
}
426
427
175050
static inline void mss4_update_dc_cache(MSS4Context *c, int mb_x)
428
{
429
    int i;
430
431
175050
    c->dc_cache[0][TOP]  = c->prev_dc[0][mb_x * 2 + 1];
432
175050
    c->dc_cache[0][LEFT] = 0;
433
175050
    c->dc_cache[1][TOP]  = 0;
434
175050
    c->dc_cache[1][LEFT] = 0;
435
436
525150
    for (i = 0; i < 2; i++)
437
350100
        c->prev_dc[0][mb_x * 2 + i] = 0;
438
439
525150
    for (i = 1; i < 3; i++) {
440
350100
        c->dc_cache[i + 1][TOP]  = c->prev_dc[i][mb_x];
441
350100
        c->dc_cache[i + 1][LEFT] = 0;
442
350100
        c->prev_dc[i][mb_x]      = 0;
443
    }
444
175050
}
445
446
145
static int mss4_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
447
                             AVPacket *avpkt)
448
{
449
145
    const uint8_t *buf = avpkt->data;
450
145
    int buf_size = avpkt->size;
451
145
    MSS4Context *c = avctx->priv_data;
452
    GetBitContext gb;
453
    GetByteContext bc;
454
    uint8_t *dst[3];
455
    int width, height, quality, frame_type;
456
    int x, y, i, mb_width, mb_height, blk_type;
457
    int ret;
458
459
145
    if (buf_size < HEADER_SIZE) {
460
        av_log(avctx, AV_LOG_ERROR,
461
               "Frame should have at least %d bytes, got %d instead\n",
462
               HEADER_SIZE, buf_size);
463
        return AVERROR_INVALIDDATA;
464
    }
465
466
145
    bytestream2_init(&bc, buf, buf_size);
467
145
    width      = bytestream2_get_be16(&bc);
468
145
    height     = bytestream2_get_be16(&bc);
469
145
    bytestream2_skip(&bc, 2);
470
145
    quality    = bytestream2_get_byte(&bc);
471
145
    frame_type = bytestream2_get_byte(&bc);
472
473
145
    if (width > avctx->width ||
474
145
        height != avctx->height) {
475
        av_log(avctx, AV_LOG_ERROR, "Invalid frame dimensions %dx%d\n",
476
               width, height);
477
        return AVERROR_INVALIDDATA;
478
    }
479

145
    if (quality < 1 || quality > 100) {
480
        av_log(avctx, AV_LOG_ERROR, "Invalid quality setting %d\n", quality);
481
        return AVERROR_INVALIDDATA;
482
    }
483

145
    if ((frame_type & ~3) || frame_type == 3) {
484
        av_log(avctx, AV_LOG_ERROR, "Invalid frame type %d\n", frame_type);
485
        return AVERROR_INVALIDDATA;
486
    }
487
488

145
    if (frame_type != SKIP_FRAME && !bytestream2_get_bytes_left(&bc)) {
489
        av_log(avctx, AV_LOG_ERROR,
490
               "Empty frame found but it is not a skip frame.\n");
491
        return AVERROR_INVALIDDATA;
492
    }
493
145
    mb_width  = FFALIGN(width,  16) >> 4;
494
145
    mb_height = FFALIGN(height, 16) >> 4;
495
496

145
    if (frame_type != SKIP_FRAME && 8*buf_size < 8*HEADER_SIZE + mb_width*mb_height)
497
        return AVERROR_INVALIDDATA;
498
499
145
    if ((ret = ff_reget_buffer(avctx, c->pic, 0)) < 0)
500
        return ret;
501
145
    c->pic->key_frame = (frame_type == INTRA_FRAME);
502
145
    c->pic->pict_type = (frame_type == INTRA_FRAME) ? AV_PICTURE_TYPE_I
503
145
                                                   : AV_PICTURE_TYPE_P;
504
145
    if (frame_type == SKIP_FRAME) {
505
98
        *got_frame      = 1;
506
98
        if ((ret = av_frame_ref(data, c->pic)) < 0)
507
            return ret;
508
509
98
        return buf_size;
510
    }
511
512
47
    if (c->quality != quality) {
513
2
        c->quality = quality;
514
6
        for (i = 0; i < 2; i++)
515
4
            ff_mss34_gen_quant_mat(c->quant_mat[i], quality, !i);
516
    }
517
518
47
    if ((ret = init_get_bits8(&gb, buf + HEADER_SIZE, buf_size - HEADER_SIZE)) < 0)
519
        return ret;
520
47
    dst[0] = c->pic->data[0];
521
47
    dst[1] = c->pic->data[1];
522
47
    dst[2] = c->pic->data[2];
523
524
47
    memset(c->prev_vec, 0, sizeof(c->prev_vec));
525
2519
    for (y = 0; y < mb_height; y++) {
526
2472
        memset(c->dc_cache, 0, sizeof(c->dc_cache));
527
191736
        for (x = 0; x < mb_width; x++) {
528
189264
            blk_type = decode012(&gb);
529

189264
            switch (blk_type) {
530
14214
            case DCT_BLOCK:
531
14214
                if (mss4_decode_dct_block(c, &gb, dst, x, y) < 0) {
532
                    av_log(avctx, AV_LOG_ERROR,
533
                           "Error decoding DCT block %d,%d\n",
534
                           x, y);
535
                    return AVERROR_INVALIDDATA;
536
                }
537
14214
                break;
538
11379
            case IMAGE_BLOCK:
539
11379
                if (mss4_decode_image_block(c, &gb, dst, x, y) < 0) {
540
                    av_log(avctx, AV_LOG_ERROR,
541
                           "Error decoding VQ block %d,%d\n",
542
                           x, y);
543
                    return AVERROR_INVALIDDATA;
544
                }
545
11379
                break;
546
163671
            case SKIP_BLOCK:
547
163671
                if (frame_type == INTRA_FRAME) {
548
                    av_log(avctx, AV_LOG_ERROR, "Skip block in intra frame\n");
549
                    return AVERROR_INVALIDDATA;
550
                }
551
163671
                break;
552
            }
553
189264
            if (blk_type != DCT_BLOCK)
554
175050
                mss4_update_dc_cache(c, x);
555
        }
556
2472
        dst[0] += c->pic->linesize[0] * 16;
557
2472
        dst[1] += c->pic->linesize[1] * 16;
558
2472
        dst[2] += c->pic->linesize[2] * 16;
559
    }
560
561
47
    if ((ret = av_frame_ref(data, c->pic)) < 0)
562
        return ret;
563
564
47
    *got_frame      = 1;
565
566
47
    return buf_size;
567
}
568
569
4
static av_cold int mss4_decode_end(AVCodecContext *avctx)
570
{
571
4
    MSS4Context * const c = avctx->priv_data;
572
    int i;
573
574
4
    av_frame_free(&c->pic);
575
16
    for (i = 0; i < 3; i++)
576
12
        av_freep(&c->prev_dc[i]);
577
578
4
    return 0;
579
}
580
581
4
static av_cold int mss4_decode_init(AVCodecContext *avctx)
582
{
583
    static AVOnce init_static_once = AV_ONCE_INIT;
584
4
    MSS4Context * const c = avctx->priv_data;
585
    int i;
586
587
16
    for (i = 0; i < 3; i++) {
588
12
        c->dc_stride[i] = FFALIGN(avctx->width, 16) >> (2 + !!i);
589
12
        c->prev_dc[i]   = av_malloc_array(c->dc_stride[i], sizeof(**c->prev_dc));
590
12
        if (!c->prev_dc[i]) {
591
            av_log(avctx, AV_LOG_ERROR, "Cannot allocate buffer\n");
592
            return AVERROR(ENOMEM);
593
        }
594
    }
595
596
4
    c->pic = av_frame_alloc();
597
4
    if (!c->pic)
598
        return AVERROR(ENOMEM);
599
600
4
    avctx->pix_fmt     = AV_PIX_FMT_YUV444P;
601
602
4
    ff_thread_once(&init_static_once, mss4_init_vlcs);
603
604
4
    return 0;
605
}
606
607
AVCodec ff_mts2_decoder = {
608
    .name           = "mts2",
609
    .long_name      = NULL_IF_CONFIG_SMALL("MS Expression Encoder Screen"),
610
    .type           = AVMEDIA_TYPE_VIDEO,
611
    .id             = AV_CODEC_ID_MTS2,
612
    .priv_data_size = sizeof(MSS4Context),
613
    .init           = mss4_decode_init,
614
    .close          = mss4_decode_end,
615
    .decode         = mss4_decode_frame,
616
    .capabilities   = AV_CODEC_CAP_DR1,
617
    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP | FF_CODEC_CAP_INIT_THREADSAFE,
618
};