aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/dds.c
blob: d473fd14cfd946eef6f1212468376b9136aad0d5 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
/*
 * DirectDraw Surface image decoder
 * Copyright (C) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * DDS decoder
 *
 * https://msdn.microsoft.com/en-us/library/bb943982%28v=vs.85%29.aspx
 */

#include <stdint.h>

#include "libavutil/imgutils.h"

#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#include "texturedsp.h"
#include "thread.h"

#define DDPF_FOURCC    (1 <<  2)
#define DDPF_PALETTE   (1 <<  5)
#define DDPF_NORMALMAP (1 << 31)

enum DDSPostProc {
    DDS_NONE = 0,
    DDS_ALPHA_EXP,
    DDS_NORMAL_MAP,
    DDS_RAW_YCOCG,
    DDS_SWAP_ALPHA,
    DDS_SWIZZLE_A2XY,
    DDS_SWIZZLE_RBXG,
    DDS_SWIZZLE_RGXB,
    DDS_SWIZZLE_RXBG,
    DDS_SWIZZLE_RXGB,
    DDS_SWIZZLE_XGBR,
    DDS_SWIZZLE_XRBG,
    DDS_SWIZZLE_XGXR,
};

enum DDSDXGIFormat {
    DXGI_FORMAT_R16G16B16A16_TYPELESS       =  9,
    DXGI_FORMAT_R16G16B16A16_FLOAT          = 10,
    DXGI_FORMAT_R16G16B16A16_UNORM          = 11,
    DXGI_FORMAT_R16G16B16A16_UINT           = 12,
    DXGI_FORMAT_R16G16B16A16_SNORM          = 13,
    DXGI_FORMAT_R16G16B16A16_SINT           = 14,

    DXGI_FORMAT_R8G8B8A8_TYPELESS           = 27,
    DXGI_FORMAT_R8G8B8A8_UNORM              = 28,
    DXGI_FORMAT_R8G8B8A8_UNORM_SRGB         = 29,
    DXGI_FORMAT_R8G8B8A8_UINT               = 30,
    DXGI_FORMAT_R8G8B8A8_SNORM              = 31,
    DXGI_FORMAT_R8G8B8A8_SINT               = 32,

    DXGI_FORMAT_BC1_TYPELESS                = 70,
    DXGI_FORMAT_BC1_UNORM                   = 71,
    DXGI_FORMAT_BC1_UNORM_SRGB              = 72,
    DXGI_FORMAT_BC2_TYPELESS                = 73,
    DXGI_FORMAT_BC2_UNORM                   = 74,
    DXGI_FORMAT_BC2_UNORM_SRGB              = 75,
    DXGI_FORMAT_BC3_TYPELESS                = 76,
    DXGI_FORMAT_BC3_UNORM                   = 77,
    DXGI_FORMAT_BC3_UNORM_SRGB              = 78,
    DXGI_FORMAT_BC4_TYPELESS                = 79,
    DXGI_FORMAT_BC4_UNORM                   = 80,
    DXGI_FORMAT_BC4_SNORM                   = 81,
    DXGI_FORMAT_BC5_TYPELESS                = 82,
    DXGI_FORMAT_BC5_UNORM                   = 83,
    DXGI_FORMAT_BC5_SNORM                   = 84,
    DXGI_FORMAT_B5G6R5_UNORM                = 85,
    DXGI_FORMAT_B8G8R8A8_UNORM              = 87,
    DXGI_FORMAT_B8G8R8X8_UNORM              = 88,
    DXGI_FORMAT_B8G8R8A8_TYPELESS           = 90,
    DXGI_FORMAT_B8G8R8A8_UNORM_SRGB         = 91,
    DXGI_FORMAT_B8G8R8X8_TYPELESS           = 92,
    DXGI_FORMAT_B8G8R8X8_UNORM_SRGB         = 93,
};

typedef struct DDSContext {
    TextureDSPContext texdsp;
    GetByteContext gbc;

    int compressed;
    int paletted;
    enum DDSPostProc postproc;

    const uint8_t *tex_data; // Compressed texture
    int tex_ratio;           // Compression ratio
    int slice_count;         // Number of slices for threaded operations

    /* Pointer to the selected compress or decompress function. */
    int (*tex_funct)(uint8_t *dst, ptrdiff_t stride, const uint8_t *block);
} DDSContext;

static int parse_pixel_format(AVCodecContext *avctx)
{
    DDSContext *ctx = avctx->priv_data;
    GetByteContext *gbc = &ctx->gbc;
    char buf[32];
    uint32_t flags, fourcc, gimp_tag;
    enum DDSDXGIFormat dxgi;
    int size, bpp, r, g, b, a;
    int alpha_exponent, ycocg_classic, ycocg_scaled, normal_map, array;

    /* Alternative DDS implementations use reserved1 as custom header. */
    bytestream2_skip(gbc, 4 * 3);
    gimp_tag = bytestream2_get_le32(gbc);
    alpha_exponent = gimp_tag == MKTAG('A', 'E', 'X', 'P');
    ycocg_classic  = gimp_tag == MKTAG('Y', 'C', 'G', '1');
    ycocg_scaled   = gimp_tag == MKTAG('Y', 'C', 'G', '2');
    bytestream2_skip(gbc, 4 * 7);

    /* Now the real DDPF starts. */
    size = bytestream2_get_le32(gbc);
    if (size != 32) {
        av_log(avctx, AV_LOG_ERROR, "Invalid pixel format header %d.\n", size);
        return AVERROR_INVALIDDATA;
    }
    flags = bytestream2_get_le32(gbc);
    ctx->compressed = flags & DDPF_FOURCC;
    ctx->paletted   = flags & DDPF_PALETTE;
    normal_map      = flags & DDPF_NORMALMAP;
    fourcc = bytestream2_get_le32(gbc);

    if (ctx->compressed && ctx->paletted) {
        av_log(avctx, AV_LOG_WARNING,
               "Disabling invalid palette flag for compressed dds.\n");
        ctx->paletted = 0;
    }

    bpp = bytestream2_get_le32(gbc); // rgbbitcount
    r   = bytestream2_get_le32(gbc); // rbitmask
    g   = bytestream2_get_le32(gbc); // gbitmask
    b   = bytestream2_get_le32(gbc); // bbitmask
    a   = bytestream2_get_le32(gbc); // abitmask

    bytestream2_skip(gbc, 4); // caps
    bytestream2_skip(gbc, 4); // caps2
    bytestream2_skip(gbc, 4); // caps3
    bytestream2_skip(gbc, 4); // caps4
    bytestream2_skip(gbc, 4); // reserved2

    av_get_codec_tag_string(buf, sizeof(buf), fourcc);
    av_log(avctx, AV_LOG_VERBOSE, "fourcc %s bpp %d "
           "r 0x%x g 0x%x b 0x%x a 0x%x\n", buf, bpp, r, g, b, a);
    if (gimp_tag) {
        av_get_codec_tag_string(buf, sizeof(buf), gimp_tag);
        av_log(avctx, AV_LOG_VERBOSE, "and GIMP-DDS tag %s\n", buf);
    }

    if (ctx->compressed)
        avctx->pix_fmt = AV_PIX_FMT_RGBA;

    if (ctx->compressed) {
        switch (fourcc) {
        case MKTAG('D', 'X', 'T', '1'):
            ctx->tex_ratio = 8;
            ctx->tex_funct = ctx->texdsp.dxt1a_block;
            break;
        case MKTAG('D', 'X', 'T', '2'):
            ctx->tex_ratio = 16;
            ctx->tex_funct = ctx->texdsp.dxt2_block;
            break;
        case MKTAG('D', 'X', 'T', '3'):
            ctx->tex_ratio = 16;
            ctx->tex_funct = ctx->texdsp.dxt3_block;
            break;
        case MKTAG('D', 'X', 'T', '4'):
            ctx->tex_ratio = 16;
            ctx->tex_funct = ctx->texdsp.dxt4_block;
            break;
        case MKTAG('D', 'X', 'T', '5'):
            ctx->tex_ratio = 16;
            if (ycocg_scaled)
                ctx->tex_funct = ctx->texdsp.dxt5ys_block;
            else if (ycocg_classic)
                ctx->tex_funct = ctx->texdsp.dxt5y_block;
            else
                ctx->tex_funct = ctx->texdsp.dxt5_block;
            break;
        case MKTAG('R', 'X', 'G', 'B'):
            ctx->tex_ratio = 16;
            ctx->tex_funct = ctx->texdsp.dxt5_block;
            /* This format may be considered as a normal map,
             * but it is handled differently in a separate postproc. */
            ctx->postproc = DDS_SWIZZLE_RXGB;
            normal_map = 0;
            break;
        case MKTAG('A', 'T', 'I', '1'):
        case MKTAG('B', 'C', '4', 'U'):
            ctx->tex_ratio = 8;
            ctx->tex_funct = ctx->texdsp.rgtc1u_block;
            break;
        case MKTAG('B', 'C', '4', 'S'):
            ctx->tex_ratio = 8;
            ctx->tex_funct = ctx->texdsp.rgtc1s_block;
            break;
        case MKTAG('A', 'T', 'I', '2'):
            /* RGT2 variant with swapped R and G (3Dc)*/
            ctx->tex_ratio = 16;
            ctx->tex_funct = ctx->texdsp.dxn3dc_block;
            break;
        case MKTAG('B', 'C', '5', 'U'):
            ctx->tex_ratio = 16;
            ctx->tex_funct = ctx->texdsp.rgtc2u_block;
            break;
        case MKTAG('B', 'C', '5', 'S'):
            ctx->tex_ratio = 16;
            ctx->tex_funct = ctx->texdsp.rgtc2s_block;
            break;
        case MKTAG('U', 'Y', 'V', 'Y'):
            ctx->compressed = 0;
            avctx->pix_fmt = AV_PIX_FMT_UYVY422;
            break;
        case MKTAG('Y', 'U', 'Y', '2'):
            ctx->compressed = 0;
            avctx->pix_fmt = AV_PIX_FMT_YUYV422;
            break;
        case MKTAG('P', '8', ' ', ' '):
            /* ATI Palette8, same as normal palette */
            ctx->compressed = 0;
            ctx->paletted   = 1;
            avctx->pix_fmt  = AV_PIX_FMT_PAL8;
            break;
        case MKTAG('D', 'X', '1', '0'):
            /* DirectX 10 extra header */
            dxgi = bytestream2_get_le32(gbc);
            bytestream2_skip(gbc, 4); // resourceDimension
            bytestream2_skip(gbc, 4); // miscFlag
            array = bytestream2_get_le32(gbc);
            bytestream2_skip(gbc, 4); // miscFlag2

            if (array != 0)
                av_log(avctx, AV_LOG_VERBOSE,
                       "Found array of size %d (ignored).\n", array);

            /* Only BC[1-5] are actually compressed. */
            ctx->compressed = (dxgi >= 70) && (dxgi <= 84);

            av_log(avctx, AV_LOG_VERBOSE, "DXGI format %d.\n", dxgi);
            switch (dxgi) {
            /* RGB types. */
            case DXGI_FORMAT_R16G16B16A16_TYPELESS:
            case DXGI_FORMAT_R16G16B16A16_FLOAT:
            case DXGI_FORMAT_R16G16B16A16_UNORM:
            case DXGI_FORMAT_R16G16B16A16_UINT:
            case DXGI_FORMAT_R16G16B16A16_SNORM:
            case DXGI_FORMAT_R16G16B16A16_SINT:
                avctx->pix_fmt = AV_PIX_FMT_BGRA64;
                break;
            case DXGI_FORMAT_R8G8B8A8_UNORM_SRGB:
                avctx->colorspace = AVCOL_SPC_RGB;
            case DXGI_FORMAT_R8G8B8A8_TYPELESS:
            case DXGI_FORMAT_R8G8B8A8_UNORM:
            case DXGI_FORMAT_R8G8B8A8_UINT:
            case DXGI_FORMAT_R8G8B8A8_SNORM:
            case DXGI_FORMAT_R8G8B8A8_SINT:
                avctx->pix_fmt = AV_PIX_FMT_BGRA;
                break;
            case DXGI_FORMAT_B8G8R8A8_UNORM_SRGB:
                avctx->colorspace = AVCOL_SPC_RGB;
            case DXGI_FORMAT_B8G8R8A8_TYPELESS:
            case DXGI_FORMAT_B8G8R8A8_UNORM:
                avctx->pix_fmt = AV_PIX_FMT_RGBA;
                break;
            case DXGI_FORMAT_B8G8R8X8_UNORM_SRGB:
                avctx->colorspace = AVCOL_SPC_RGB;
            case DXGI_FORMAT_B8G8R8X8_TYPELESS:
            case DXGI_FORMAT_B8G8R8X8_UNORM:
                avctx->pix_fmt = AV_PIX_FMT_RGBA; // opaque
                break;
            case DXGI_FORMAT_B5G6R5_UNORM:
                avctx->pix_fmt = AV_PIX_FMT_RGB565LE;
                break;
            /* Texture types. */
            case DXGI_FORMAT_BC1_UNORM_SRGB:
                avctx->colorspace = AVCOL_SPC_RGB;
            case DXGI_FORMAT_BC1_TYPELESS:
            case DXGI_FORMAT_BC1_UNORM:
                ctx->tex_ratio = 8;
                ctx->tex_funct = ctx->texdsp.dxt1a_block;
                break;
            case DXGI_FORMAT_BC2_UNORM_SRGB:
                avctx->colorspace = AVCOL_SPC_RGB;
            case DXGI_FORMAT_BC2_TYPELESS:
            case DXGI_FORMAT_BC2_UNORM:
                ctx->tex_ratio = 16;
                ctx->tex_funct = ctx->texdsp.dxt3_block;
                break;
            case DXGI_FORMAT_BC3_UNORM_SRGB:
                avctx->colorspace = AVCOL_SPC_RGB;
            case DXGI_FORMAT_BC3_TYPELESS:
            case DXGI_FORMAT_BC3_UNORM:
                ctx->tex_ratio = 16;
                ctx->tex_funct = ctx->texdsp.dxt5_block;
                break;
            case DXGI_FORMAT_BC4_TYPELESS:
            case DXGI_FORMAT_BC4_UNORM:
                ctx->tex_ratio = 8;
                ctx->tex_funct = ctx->texdsp.rgtc1u_block;
                break;
            case DXGI_FORMAT_BC4_SNORM:
                ctx->tex_ratio = 8;
                ctx->tex_funct = ctx->texdsp.rgtc1s_block;
                break;
            case DXGI_FORMAT_BC5_TYPELESS:
            case DXGI_FORMAT_BC5_UNORM:
                ctx->tex_ratio = 16;
                ctx->tex_funct = ctx->texdsp.rgtc2u_block;
                break;
            case DXGI_FORMAT_BC5_SNORM:
                ctx->tex_ratio = 16;
                ctx->tex_funct = ctx->texdsp.rgtc2s_block;
                break;
            default:
                av_log(avctx, AV_LOG_ERROR,
                       "Unsupported DXGI format %d.\n", dxgi);
                return AVERROR_INVALIDDATA;
            }
            break;
        default:
            av_log(avctx, AV_LOG_ERROR, "Unsupported %s fourcc.\n", buf);
            return AVERROR_INVALIDDATA;
        }
    } else if (ctx->paletted) {
        if (bpp == 8) {
            avctx->pix_fmt = AV_PIX_FMT_PAL8;
        } else {
            av_log(avctx, AV_LOG_ERROR, "Unsupported palette bpp %d.\n", bpp);
            return AVERROR_INVALIDDATA;
        }
    } else {
        /*  8 bpp */
        if (bpp == 8 && r == 0xff && g == 0 && b == 0 && a == 0)
            avctx->pix_fmt = AV_PIX_FMT_GRAY8;
        /* 16 bpp */
        else if (bpp == 16 && r == 0xff && g == 0 && b == 0 && a == 0xff00)
            avctx->pix_fmt = AV_PIX_FMT_YA8;
        else if (bpp == 16 && r == 0xffff && g == 0 && b == 0 && a == 0)
            avctx->pix_fmt = AV_PIX_FMT_GRAY16LE;
        else if (bpp == 16 && r == 0xf800 && g == 0x7e0 && b == 0x1f && a == 0)
            avctx->pix_fmt = AV_PIX_FMT_RGB565LE;
        /* 24 bpp */
        else if (bpp == 24 && r == 0xff0000 && g == 0xff00 && b == 0xff && a == 0)
            avctx->pix_fmt = AV_PIX_FMT_BGR24;
        /* 32 bpp */
        else if (bpp == 32 && r == 0xff0000 && g == 0xff00 && b == 0xff && a == 0)
            avctx->pix_fmt = AV_PIX_FMT_BGR0; // opaque
        else if (bpp == 32 && r == 0xff && g == 0xff00 && b == 0xff0000 && a == 0)
            avctx->pix_fmt = AV_PIX_FMT_RGB0; // opaque
        else if (bpp == 32 && r == 0xff0000 && g == 0xff00 && b == 0xff && a == 0xff000000)
            avctx->pix_fmt = AV_PIX_FMT_BGRA;
        else if (bpp == 32 && r == 0xff && g == 0xff00 && b == 0xff0000 && a == 0xff000000)
            avctx->pix_fmt = AV_PIX_FMT_RGBA;
        /* give up */
        else {
            av_log(avctx, AV_LOG_ERROR, "Unknown pixel format "
                   "[bpp %d r 0x%x g 0x%x b 0x%x a 0x%x].\n", bpp, r, g, b, a);
            return AVERROR_INVALIDDATA;
        }
    }

    /* Set any remaining post-proc that should happen before frame is ready. */
    if (alpha_exponent)
        ctx->postproc = DDS_ALPHA_EXP;
    else if (normal_map)
        ctx->postproc = DDS_NORMAL_MAP;
    else if (ycocg_classic && !ctx->compressed)
        ctx->postproc = DDS_RAW_YCOCG;
    else if (avctx->pix_fmt == AV_PIX_FMT_YA8)
        ctx->postproc = DDS_SWAP_ALPHA;

    /* ATI/NVidia variants sometimes add swizzling in bpp. */
    switch (bpp) {
    case MKTAG('A', '2', 'X', 'Y'):
        ctx->postproc = DDS_SWIZZLE_A2XY;
        break;
    case MKTAG('x', 'G', 'B', 'R'):
        ctx->postproc = DDS_SWIZZLE_XGBR;
        break;
    case MKTAG('x', 'R', 'B', 'G'):
        ctx->postproc = DDS_SWIZZLE_XRBG;
        break;
    case MKTAG('R', 'B', 'x', 'G'):
        ctx->postproc = DDS_SWIZZLE_RBXG;
        break;
    case MKTAG('R', 'G', 'x', 'B'):
        ctx->postproc = DDS_SWIZZLE_RGXB;
        break;
    case MKTAG('R', 'x', 'B', 'G'):
        ctx->postproc = DDS_SWIZZLE_RXBG;
        break;
    case MKTAG('x', 'G', 'x', 'R'):
        ctx->postproc = DDS_SWIZZLE_XGXR;
        break;
    case MKTAG('A', '2', 'D', '5'):
        ctx->postproc = DDS_NORMAL_MAP;
        break;
    }

    return 0;
}

static int decompress_texture_thread(AVCodecContext *avctx, void *arg,
                                     int slice, int thread_nb)
{
    DDSContext *ctx = avctx->priv_data;
    AVFrame *frame = arg;
    const uint8_t *d = ctx->tex_data;
    int w_block = avctx->coded_width / TEXTURE_BLOCK_W;
    int h_block = avctx->coded_height / TEXTURE_BLOCK_H;
    int x, y;
    int start_slice, end_slice;
    int base_blocks_per_slice = h_block / ctx->slice_count;
    int remainder_blocks = h_block % ctx->slice_count;

    /* When the frame height (in blocks) doesn't divide evenly between the
     * number of slices, spread the remaining blocks evenly between the first
     * operations */
    start_slice = slice * base_blocks_per_slice;
    /* Add any extra blocks (one per slice) that have been added before this slice */
    start_slice += FFMIN(slice, remainder_blocks);

    end_slice = start_slice + base_blocks_per_slice;
    /* Add an extra block if there are still remainder blocks to be accounted for */
    if (slice < remainder_blocks)
        end_slice++;

    for (y = start_slice; y < end_slice; y++) {
        uint8_t *p = frame->data[0] + y * frame->linesize[0] * TEXTURE_BLOCK_H;
        int off  = y * w_block;
        for (x = 0; x < w_block; x++) {
            ctx->tex_funct(p + x * 16, frame->linesize[0],
                           d + (off + x) * ctx->tex_ratio);
        }
    }

    return 0;
}

static void do_swizzle(AVFrame *frame, int x, int y)
{
    int i;
    for (i = 0; i < frame->linesize[0] * frame->height; i += 4) {
        uint8_t *src = frame->data[0] + i;
        FFSWAP(uint8_t, src[x], src[y]);
    }
}

static void run_postproc(AVCodecContext *avctx, AVFrame *frame)
{
    DDSContext *ctx = avctx->priv_data;
    int i, x_off;

    switch (ctx->postproc) {
    case DDS_ALPHA_EXP:
        /* Alpha-exponential mode divides each channel by the maximum
         * R, G or B value, and stores the multiplying factor in the
         * alpha channel. */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing alpha exponent.\n");

        for (i = 0; i < frame->linesize[0] * frame->height; i += 4) {
            uint8_t *src = frame->data[0] + i;
            int r = src[0];
            int g = src[1];
            int b = src[2];
            int a = src[3];

            src[0] = r * a / 255;
            src[1] = g * a / 255;
            src[2] = b * a / 255;
            src[3] = 255;
        }
        break;
    case DDS_NORMAL_MAP:
        /* Normal maps work in the XYZ color space and they encode
         * X in R or in A, depending on the texture type, Y in G and
         * derive Z with a square root of the distance.
         *
         * http://www.realtimecollisiondetection.net/blog/?p=28 */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing normal map.\n");

        x_off = ctx->tex_ratio == 8 ? 0 : 3;
        for (i = 0; i < frame->linesize[0] * frame->height; i += 4) {
            uint8_t *src = frame->data[0] + i;
            int x = src[x_off];
            int y = src[1];
            int z = 127;

            int d = (255 * 255 - x * x - y * y) / 2;
            if (d > 0)
                z = rint(sqrtf(d));

            src[0] = x;
            src[1] = y;
            src[2] = z;
            src[3] = 255;
        }
        break;
    case DDS_RAW_YCOCG:
        /* Data is Y-Co-Cg-A and not RGBA, but they are represented
         * with the same masks in the DDPF header. */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing raw YCoCg.\n");

        for (i = 0; i < frame->linesize[0] * frame->height; i += 4) {
            uint8_t *src = frame->data[0] + i;
            int a  = src[0];
            int cg = src[1] - 128;
            int co = src[2] - 128;
            int y  = src[3];

            src[0] = av_clip_uint8(y + co - cg);
            src[1] = av_clip_uint8(y + cg);
            src[2] = av_clip_uint8(y - co - cg);
            src[3] = a;
        }
        break;
    case DDS_SWAP_ALPHA:
        /* Alpha and Luma are stored swapped. */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing swapped Luma/Alpha.\n");

        for (i = 0; i < frame->linesize[0] * frame->height; i += 2) {
            uint8_t *src = frame->data[0] + i;
            FFSWAP(uint8_t, src[0], src[1]);
        }
        break;
    case DDS_SWIZZLE_A2XY:
        /* Swap R and G, often used to restore a standard RGTC2. */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing A2XY swizzle.\n");
        do_swizzle(frame, 0, 1);
        break;
    case DDS_SWIZZLE_RBXG:
        /* Swap G and A, then B and new A (G). */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing RBXG swizzle.\n");
        do_swizzle(frame, 1, 3);
        do_swizzle(frame, 2, 3);
        break;
    case DDS_SWIZZLE_RGXB:
        /* Swap B and A. */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing RGXB swizzle.\n");
        do_swizzle(frame, 2, 3);
        break;
    case DDS_SWIZZLE_RXBG:
        /* Swap G and A. */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing RXBG swizzle.\n");
        do_swizzle(frame, 1, 3);
        break;
    case DDS_SWIZZLE_RXGB:
        /* Swap R and A (misleading name). */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing RXGB swizzle.\n");
        do_swizzle(frame, 0, 3);
        break;
    case DDS_SWIZZLE_XGBR:
        /* Swap B and A, then R and new A (B). */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing XGBR swizzle.\n");
        do_swizzle(frame, 2, 3);
        do_swizzle(frame, 0, 3);
        break;
    case DDS_SWIZZLE_XGXR:
        /* Swap G and A, then R and new A (G), then new R (G) and new G (A).
         * This variant does not store any B component. */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing XGXR swizzle.\n");
        do_swizzle(frame, 1, 3);
        do_swizzle(frame, 0, 3);
        do_swizzle(frame, 0, 1);
        break;
    case DDS_SWIZZLE_XRBG:
        /* Swap G and A, then R and new A (G). */
        av_log(avctx, AV_LOG_DEBUG, "Post-processing XRBG swizzle.\n");
        do_swizzle(frame, 1, 3);
        do_swizzle(frame, 0, 3);
        break;
    }
}

static int dds_decode(AVCodecContext *avctx, void *data,
                      int *got_frame, AVPacket *avpkt)
{
    DDSContext *ctx = avctx->priv_data;
    GetByteContext *gbc = &ctx->gbc;
    AVFrame *frame = data;
    int mipmap;
    int ret;

    ff_texturedsp_init(&ctx->texdsp);
    bytestream2_init(gbc, avpkt->data, avpkt->size);

    if (bytestream2_get_bytes_left(gbc) < 128) {
        av_log(avctx, AV_LOG_ERROR, "Frame is too small (%d).\n",
               bytestream2_get_bytes_left(gbc));
        return AVERROR_INVALIDDATA;
    }

    if (bytestream2_get_le32(gbc) != MKTAG('D', 'D', 'S', ' ') ||
        bytestream2_get_le32(gbc) != 124) { // header size
        av_log(avctx, AV_LOG_ERROR, "Invalid DDS header.\n");
        return AVERROR_INVALIDDATA;
    }

    bytestream2_skip(gbc, 4); // flags

    avctx->height = bytestream2_get_le32(gbc);
    avctx->width  = bytestream2_get_le32(gbc);
    ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
    if (ret < 0) {
        av_log(avctx, AV_LOG_ERROR, "Invalid image size %dx%d.\n",
               avctx->width, avctx->height);
        return ret;
    }

    /* Since codec is based on 4x4 blocks, size is aligned to 4. */
    avctx->coded_width  = FFALIGN(avctx->width,  TEXTURE_BLOCK_W);
    avctx->coded_height = FFALIGN(avctx->height, TEXTURE_BLOCK_H);

    bytestream2_skip(gbc, 4); // pitch
    bytestream2_skip(gbc, 4); // depth
    mipmap = bytestream2_get_le32(gbc);
    if (mipmap != 0)
        av_log(avctx, AV_LOG_VERBOSE, "Found %d mipmaps (ignored).\n", mipmap);

    /* Extract pixel format information, considering additional elements
     * in reserved1 and reserved2. */
    ret = parse_pixel_format(avctx);
    if (ret < 0)
        return ret;

    ret = ff_get_buffer(avctx, frame, 0);
    if (ret < 0)
        return ret;

    if (ctx->compressed) {
        int size = (avctx->coded_height / TEXTURE_BLOCK_H) *
                   (avctx->coded_width / TEXTURE_BLOCK_W) * ctx->tex_ratio;
        ctx->slice_count = av_clip(avctx->thread_count, 1,
                                   avctx->coded_height / TEXTURE_BLOCK_H);

        if (bytestream2_get_bytes_left(gbc) < size) {
            av_log(avctx, AV_LOG_ERROR,
                   "Compressed Buffer is too small (%d < %d).\n",
                   bytestream2_get_bytes_left(gbc), size);
            return AVERROR_INVALIDDATA;
        }

        /* Use the decompress function on the texture, one block per thread. */
        ctx->tex_data = gbc->buffer;
        avctx->execute2(avctx, decompress_texture_thread, frame, NULL, ctx->slice_count);
    } else {
        int linesize = av_image_get_linesize(avctx->pix_fmt, frame->width, 0);

        if (ctx->paletted) {
            int i;
            /* Use the first 1024 bytes as palette, then copy the rest. */
            bytestream2_get_buffer(gbc, frame->data[1], 256 * 4);
            for (i = 0; i < 256; i++)
                AV_WN32(frame->data[1] + i*4,
                        (frame->data[1][2+i*4]<<0)+
                        (frame->data[1][1+i*4]<<8)+
                        (frame->data[1][0+i*4]<<16)+
                        (frame->data[1][3+i*4]<<24)
                );

            frame->palette_has_changed = 1;
        }

        if (bytestream2_get_bytes_left(gbc) < frame->height * linesize) {
            av_log(avctx, AV_LOG_ERROR, "Buffer is too small (%d < %d).\n",
                   bytestream2_get_bytes_left(gbc), frame->height * linesize);
            return AVERROR_INVALIDDATA;
        }

        av_image_copy_plane(frame->data[0], frame->linesize[0],
                            gbc->buffer, linesize,
                            linesize, frame->height);
    }

    /* Run any post processing here if needed. */
    if (avctx->pix_fmt == AV_PIX_FMT_BGRA ||
        avctx->pix_fmt == AV_PIX_FMT_RGBA ||
        avctx->pix_fmt == AV_PIX_FMT_RGB0 ||
        avctx->pix_fmt == AV_PIX_FMT_BGR0 ||
        avctx->pix_fmt == AV_PIX_FMT_YA8)
        run_postproc(avctx, frame);

    /* Frame is ready to be output. */
    frame->pict_type = AV_PICTURE_TYPE_I;
    frame->key_frame = 1;
    *got_frame = 1;

    return avpkt->size;
}

AVCodec ff_dds_decoder = {
    .name           = "dds",
    .long_name      = NULL_IF_CONFIG_SMALL("DirectDraw Surface image decoder"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_DDS,
    .decode         = dds_decode,
    .priv_data_size = sizeof(DDSContext),
    .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_SLICE_THREADS,
    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE
};