aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/tdsc.c
blob: ab0a70859b25141ba31854c2a351db8517eeb75a (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
/*
 * TDSC 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
 * TDSC decoder
 *
 * Fourcc: TSDC
 *
 * TDSC is very simple. It codes picture by tiles, storing them in raw BGR24
 * format or compressing them in JPEG. Frames can be full pictures or just
 * updates to the previous frame. Cursor is found in its own frame or at the
 * bottom of the picture. Every frame is then packed with zlib.
 *
 * Supports: BGR24
 */

#include <stdint.h>
#include <zlib.h>

#include "libavutil/imgutils.h"
#include "libavutil/mem.h"

#include "avcodec.h"
#include "bytestream.h"
#include "codec_internal.h"
#include "decode.h"

#define BITMAPINFOHEADER_SIZE 0x28
#define TDSF_HEADER_SIZE      0x56
#define TDSB_HEADER_SIZE      0x08

typedef struct TDSCContext {
    AVCodecContext *jpeg_avctx;   // wrapper context for MJPEG

    int width, height;
    GetByteContext gbc;

    AVFrame *refframe;          // full decoded frame (without cursor)
    AVPacket *jpkt;             // encoded JPEG tile
    AVFrame *jpgframe;          // decoded JPEG tile
    uint8_t *tilebuffer;        // buffer containing tile data

    /* zlib interaction */
    uint8_t *deflatebuffer;
    uLongf deflatelen;

    /* All that is cursor */
    uint8_t    *cursor;
    int        cursor_stride;
    int        cursor_w, cursor_h, cursor_x, cursor_y;
    int        cursor_hot_x, cursor_hot_y;
} TDSCContext;

/* 1 byte bits, 1 byte planes, 2 bytes format (probably) */
enum TDSCCursorFormat {
    CUR_FMT_MONO = 0x01010004,
    CUR_FMT_BGRA = 0x20010004,
    CUR_FMT_RGBA = 0x20010008,
};

static av_cold int tdsc_close(AVCodecContext *avctx)
{
    TDSCContext *ctx = avctx->priv_data;

    av_frame_free(&ctx->refframe);
    av_frame_free(&ctx->jpgframe);
    av_packet_free(&ctx->jpkt);
    av_freep(&ctx->deflatebuffer);
    av_freep(&ctx->tilebuffer);
    av_freep(&ctx->cursor);
    avcodec_free_context(&ctx->jpeg_avctx);

    return 0;
}

static av_cold int tdsc_init(AVCodecContext *avctx)
{
    TDSCContext *ctx = avctx->priv_data;
    const AVCodec *codec;
    int ret;

    avctx->pix_fmt = AV_PIX_FMT_BGR24;

    /* These needs to be set to estimate buffer and frame size */
    if (!(avctx->width && avctx->height)) {
        av_log(avctx, AV_LOG_ERROR, "Video size not set.\n");
        return AVERROR_INVALIDDATA;
    }

    /* This value should be large enough for a RAW-only frame plus headers */
    ctx->deflatelen = avctx->width * avctx->height * (3 + 1);
    ret = av_reallocp(&ctx->deflatebuffer, ctx->deflatelen);
    if (ret < 0)
        return ret;

    /* Allocate reference and JPEG frame */
    ctx->refframe = av_frame_alloc();
    ctx->jpgframe = av_frame_alloc();
    ctx->jpkt     = av_packet_alloc();
    if (!ctx->refframe || !ctx->jpgframe || !ctx->jpkt)
        return AVERROR(ENOMEM);

    /* Prepare everything needed for JPEG decoding */
    codec = avcodec_find_decoder(AV_CODEC_ID_MJPEG);
    if (!codec)
        return AVERROR_BUG;
    ctx->jpeg_avctx = avcodec_alloc_context3(codec);
    if (!ctx->jpeg_avctx)
        return AVERROR(ENOMEM);
    ctx->jpeg_avctx->flags = avctx->flags;
    ctx->jpeg_avctx->flags2 = avctx->flags2;
    ctx->jpeg_avctx->idct_algo = avctx->idct_algo;
    ret = avcodec_open2(ctx->jpeg_avctx, codec, NULL);
    if (ret < 0)
        return ret;

    /* Set the output pixel format on the reference frame */
    ctx->refframe->format = avctx->pix_fmt;

    return 0;
}

#define APPLY_ALPHA(src, new, alpha) \
    src = (src * (256 - alpha) + new * alpha) >> 8

/* Paint a region over a buffer, without drawing out of its bounds. */
static void tdsc_paint_cursor(AVCodecContext *avctx, uint8_t *dst, int stride)
{
    TDSCContext *ctx = avctx->priv_data;
    const uint8_t *cursor = ctx->cursor;
    int x = ctx->cursor_x - ctx->cursor_hot_x;
    int y = ctx->cursor_y - ctx->cursor_hot_y;
    int w = ctx->cursor_w;
    int h = ctx->cursor_h;
    int i, j;

    if (!ctx->cursor)
        return;

    if (x + w > ctx->width)
        w = ctx->width - x;
    if (y + h > ctx->height)
        h = ctx->height - y;
    if (x < 0) {
        w      +=  x;
        cursor += -x * 4;
    } else {
        dst    +=  x * 3;
    }
    if (y < 0) {
        h      +=  y;
        cursor += -y * ctx->cursor_stride;
    } else {
        dst    +=  y * stride;
    }
    if (w < 0 || h < 0)
        return;

    for (j = 0; j < h; j++) {
        for (i = 0; i < w; i++) {
            uint8_t alpha = cursor[i * 4];
            APPLY_ALPHA(dst[i * 3 + 0], cursor[i * 4 + 1], alpha);
            APPLY_ALPHA(dst[i * 3 + 1], cursor[i * 4 + 2], alpha);
            APPLY_ALPHA(dst[i * 3 + 2], cursor[i * 4 + 3], alpha);
        }
        dst    += stride;
        cursor += ctx->cursor_stride;
    }
}

/* Load cursor data and store it in ABGR mode. */
static int tdsc_load_cursor(AVCodecContext *avctx)
{
    TDSCContext *ctx  = avctx->priv_data;
    int i, j, k, ret, cursor_fmt;
    uint8_t *dst;

    ctx->cursor_hot_x = bytestream2_get_le16(&ctx->gbc);
    ctx->cursor_hot_y = bytestream2_get_le16(&ctx->gbc);
    ctx->cursor_w     = bytestream2_get_le16(&ctx->gbc);
    ctx->cursor_h     = bytestream2_get_le16(&ctx->gbc);

    ctx->cursor_stride = FFALIGN(ctx->cursor_w, 32) * 4;
    cursor_fmt = bytestream2_get_le32(&ctx->gbc);

    if (ctx->cursor_x >= avctx->width || ctx->cursor_y >= avctx->height) {
        av_log(avctx, AV_LOG_ERROR,
               "Invalid cursor position (%d.%d outside %dx%d).\n",
               ctx->cursor_x, ctx->cursor_y, avctx->width, avctx->height);
        return AVERROR_INVALIDDATA;
    }
    if (ctx->cursor_w < 1 || ctx->cursor_w > 256 ||
        ctx->cursor_h < 1 || ctx->cursor_h > 256) {
        av_log(avctx, AV_LOG_ERROR,
               "Invalid cursor dimensions %dx%d.\n",
               ctx->cursor_w, ctx->cursor_h);
        return AVERROR_INVALIDDATA;
    }
    if (ctx->cursor_hot_x > ctx->cursor_w ||
        ctx->cursor_hot_y > ctx->cursor_h) {
        av_log(avctx, AV_LOG_WARNING, "Invalid hotspot position %d.%d.\n",
               ctx->cursor_hot_x, ctx->cursor_hot_y);
        ctx->cursor_hot_x = FFMIN(ctx->cursor_hot_x, ctx->cursor_w - 1);
        ctx->cursor_hot_y = FFMIN(ctx->cursor_hot_y, ctx->cursor_h - 1);
    }

    ret = av_reallocp(&ctx->cursor, ctx->cursor_stride * ctx->cursor_h);
    if (ret < 0) {
        av_log(avctx, AV_LOG_ERROR, "Cannot allocate cursor buffer.\n");
        return ret;
    }

    dst = ctx->cursor;
    /* here data is packed in BE */
    switch (cursor_fmt) {
    case CUR_FMT_MONO:
        for (j = 0; j < ctx->cursor_h; j++) {
            for (i = 0; i < ctx->cursor_w; i += 32) {
                uint32_t bits = bytestream2_get_be32(&ctx->gbc);
                for (k = 0; k < 32; k++) {
                    dst[0] = !!(bits & 0x80000000);
                    dst   += 4;
                    bits <<= 1;
                }
            }
            dst += ctx->cursor_stride - ctx->cursor_w * 4;
        }

        dst = ctx->cursor;
        for (j = 0; j < ctx->cursor_h; j++) {
            for (i = 0; i < ctx->cursor_w; i += 32) {
                uint32_t bits = bytestream2_get_be32(&ctx->gbc);
                for (k = 0; k < 32; k++) {
                    int mask_bit = !!(bits & 0x80000000);
                    switch (dst[0] * 2 + mask_bit) {
                    case 0:
                        dst[0] = 0xFF;
                        dst[1] = 0x00;
                        dst[2] = 0x00;
                        dst[3] = 0x00;
                        break;
                    case 1:
                        dst[0] = 0xFF;
                        dst[1] = 0xFF;
                        dst[2] = 0xFF;
                        dst[3] = 0xFF;
                        break;
                    default:
                        dst[0] = 0x00;
                        dst[1] = 0x00;
                        dst[2] = 0x00;
                        dst[3] = 0x00;
                    }
                    dst   += 4;
                    bits <<= 1;
                }
            }
            dst += ctx->cursor_stride - ctx->cursor_w * 4;
        }
        break;
    case CUR_FMT_BGRA:
    case CUR_FMT_RGBA:
        /* Skip monochrome version of the cursor */
        bytestream2_skip(&ctx->gbc,
                         ctx->cursor_h * (FFALIGN(ctx->cursor_w, 32) >> 3));
        if (cursor_fmt & 8) { // RGBA -> ABGR
            for (j = 0; j < ctx->cursor_h; j++) {
                for (i = 0; i < ctx->cursor_w; i++) {
                    int val = bytestream2_get_be32(&ctx->gbc);
                    *dst++ = val >> 24;
                    *dst++ = val >> 16;
                    *dst++ = val >>  8;
                    *dst++ = val >>  0;
                }
                dst += ctx->cursor_stride - ctx->cursor_w * 4;
            }
        } else { // BGRA -> ABGR
            for (j = 0; j < ctx->cursor_h; j++) {
                for (i = 0; i < ctx->cursor_w; i++) {
                    int val = bytestream2_get_be32(&ctx->gbc);
                    *dst++ = val >>  0;
                    *dst++ = val >> 24;
                    *dst++ = val >> 16;
                    *dst++ = val >>  8;
                }
                dst += ctx->cursor_stride - ctx->cursor_w * 4;
            }
        }
        break;
    default:
        avpriv_request_sample(avctx, "Cursor format %08x", cursor_fmt);
        return AVERROR_PATCHWELCOME;
    }

    return 0;
}

/* Convert a single YUV pixel to RGB. */
static inline void tdsc_yuv2rgb(uint8_t *out, int Y, int U, int V)
{
    out[0] = av_clip_uint8(Y + (             91881 * V + 32768 >> 16));
    out[1] = av_clip_uint8(Y + (-22554 * U - 46802 * V + 32768 >> 16));
    out[2] = av_clip_uint8(Y + (116130 * U             + 32768 >> 16));
}

/* Convert a YUV420 buffer to a RGB buffer. */
static av_always_inline void tdsc_blit(uint8_t *dst, int dst_stride,
                                       const uint8_t *srcy, int srcy_stride,
                                       const uint8_t *srcu, const uint8_t *srcv,
                                       int srcuv_stride, int width, int height)
{
    int col, line;
    for (line = 0; line < height; line++) {
        for (col = 0; col < width; col++)
            tdsc_yuv2rgb(dst + col * 3, srcy[col],
                         srcu[col >> 1] - 128, srcv[col >> 1] - 128);

        dst  +=   dst_stride;
        srcy +=  srcy_stride;
        srcu += srcuv_stride * (line & 1);
        srcv += srcuv_stride * (line & 1);
    }
}

/* Invoke the MJPEG decoder to decode the tile. */
static int tdsc_decode_jpeg_tile(AVCodecContext *avctx, int tile_size,
                                 int x, int y, int w, int h)
{
    TDSCContext *ctx = avctx->priv_data;
    int ret;

    /* Prepare a packet and send to the MJPEG decoder */
    av_packet_unref(ctx->jpkt);
    ctx->jpkt->data = ctx->tilebuffer;
    ctx->jpkt->size = tile_size;

    ret = avcodec_send_packet(ctx->jpeg_avctx, ctx->jpkt);
    if (ret < 0) {
        av_log(avctx, AV_LOG_ERROR, "Error submitting a packet for decoding\n");
        return ret;
    }

    ret = avcodec_receive_frame(ctx->jpeg_avctx, ctx->jpgframe);
    if (ret < 0 || ctx->jpgframe->format != AV_PIX_FMT_YUVJ420P) {
        av_log(avctx, AV_LOG_ERROR,
               "JPEG decoding error (%d).\n", ret);

        /* Normally skip, error if explode */
        if (avctx->err_recognition & AV_EF_EXPLODE)
            return AVERROR_INVALIDDATA;
        else
            return 0;
    }

    /* Let's paint onto the buffer */
    tdsc_blit(ctx->refframe->data[0] + x * 3 + ctx->refframe->linesize[0] * y,
              ctx->refframe->linesize[0],
              ctx->jpgframe->data[0], ctx->jpgframe->linesize[0],
              ctx->jpgframe->data[1], ctx->jpgframe->data[2],
              ctx->jpgframe->linesize[1], w, h);

    av_frame_unref(ctx->jpgframe);

    return 0;
}

/* Parse frame and either copy data or decode JPEG. */
static int tdsc_decode_tiles(AVCodecContext *avctx, int number_tiles)
{
    TDSCContext *ctx = avctx->priv_data;
    int i;

    /* Iterate over the number of tiles */
    for (i = 0; i < number_tiles; i++) {
        int tile_size;
        int tile_mode;
        int x, y, x2, y2, w, h;
        int ret;

        if (bytestream2_get_bytes_left(&ctx->gbc) < 4 ||
            bytestream2_get_le32(&ctx->gbc) != MKTAG('T','D','S','B') ||
            bytestream2_get_bytes_left(&ctx->gbc) < TDSB_HEADER_SIZE - 4) {
            av_log(avctx, AV_LOG_ERROR, "TDSB tag is too small.\n");
            return AVERROR_INVALIDDATA;
        }

        tile_size = bytestream2_get_le32(&ctx->gbc);
        if (bytestream2_get_bytes_left(&ctx->gbc) < tile_size)
            return AVERROR_INVALIDDATA;

        tile_mode = bytestream2_get_le32(&ctx->gbc);
        bytestream2_skip(&ctx->gbc, 4); // unknown
        x = bytestream2_get_le32(&ctx->gbc);
        y = bytestream2_get_le32(&ctx->gbc);
        x2 = bytestream2_get_le32(&ctx->gbc);
        y2 = bytestream2_get_le32(&ctx->gbc);

        if (x < 0 || y < 0 || x2 <= x || y2 <= y ||
            x2 > ctx->width || y2 > ctx->height
        ) {
            av_log(avctx, AV_LOG_ERROR,
                   "Invalid tile position (%d.%d %d.%d outside %dx%d).\n",
                   x, y, x2, y2, ctx->width, ctx->height);
            return AVERROR_INVALIDDATA;
        }
        w = x2 - x;
        h = y2 - y;

        ret = av_reallocp(&ctx->tilebuffer, tile_size);
        if (!ctx->tilebuffer)
            return ret;

        bytestream2_get_buffer(&ctx->gbc, ctx->tilebuffer, tile_size);

        if (tile_mode == MKTAG('G','E','P','J')) {
            /* Decode JPEG tile and copy it in the reference frame */
            ret = tdsc_decode_jpeg_tile(avctx, tile_size, x, y, w, h);
            if (ret < 0)
                return ret;
        } else if (tile_mode == MKTAG(' ','W','A','R')) {
            /* Just copy the buffer to output */
            av_image_copy_plane(ctx->refframe->data[0] + x * 3 +
                                ctx->refframe->linesize[0] * y,
                                ctx->refframe->linesize[0], ctx->tilebuffer,
                                w * 3, w * 3, h);
        } else {
            av_log(avctx, AV_LOG_ERROR, "Unknown tile type %08x.\n", tile_mode);
            return AVERROR_INVALIDDATA;
        }
        av_log(avctx, AV_LOG_DEBUG, "Tile %d, %dx%d (%d.%d)\n", i, w, h, x, y);
    }

    return 0;
}

static int tdsc_parse_tdsf(AVCodecContext *avctx, int number_tiles)
{
    TDSCContext *ctx = avctx->priv_data;
    int ret, w, h, init_refframe = !ctx->refframe->data[0];

    /* BITMAPINFOHEADER
     * http://msdn.microsoft.com/en-us/library/windows/desktop/dd183376.aspx */
    if (bytestream2_get_le32(&ctx->gbc) != BITMAPINFOHEADER_SIZE)
        return AVERROR_INVALIDDATA;

    /* Store size, but wait for context reinit before updating avctx */
    w =  bytestream2_get_le32(&ctx->gbc);
    h = -bytestream2_get_le32(&ctx->gbc);

    if (bytestream2_get_le16(&ctx->gbc) != 1 ||  // 1 plane
        bytestream2_get_le16(&ctx->gbc) != 24)   // BGR24
        return AVERROR_INVALIDDATA;

    bytestream2_skip(&ctx->gbc, 24); // unused fields

    /* Update sizes */
    if (avctx->width != w || avctx->height != h) {
        av_log(avctx, AV_LOG_DEBUG, "Size update %dx%d -> %d%d.\n",
               avctx->width, avctx->height, ctx->width, ctx->height);
        ret = ff_set_dimensions(avctx, w, h);
        if (ret < 0)
            return ret;
        init_refframe = 1;
    }
    ctx->refframe->width  = ctx->width  = w;
    ctx->refframe->height = ctx->height = h;

    /* Allocate the reference frame if not already done or on size change */
    if (init_refframe) {
        ret = av_frame_get_buffer(ctx->refframe, 0);
        if (ret < 0)
            return ret;
    }

    /* Decode all tiles in a frame */
    return tdsc_decode_tiles(avctx, number_tiles);
}

static int tdsc_parse_dtsm(AVCodecContext *avctx)
{
    TDSCContext *ctx = avctx->priv_data;
    int ret;
    int action = bytestream2_get_le32(&ctx->gbc);

    bytestream2_skip(&ctx->gbc, 4); // some kind of ID or version maybe?

    if (action == 2 || action == 3) {
        /* Load cursor coordinates */
        ctx->cursor_x = bytestream2_get_le32(&ctx->gbc);
        ctx->cursor_y = bytestream2_get_le32(&ctx->gbc);

        /* Load a full cursor sprite */
        if (action == 3) {
            ret = tdsc_load_cursor(avctx);
            /* Do not consider cursor errors fatal unless in explode mode */
            if (ret < 0 && (avctx->err_recognition & AV_EF_EXPLODE))
                return ret;
        }
    } else {
        avpriv_request_sample(avctx, "Cursor action %d", action);
    }

    return 0;
}

static int tdsc_decode_frame(AVCodecContext *avctx, AVFrame *frame,
                             int *got_frame, AVPacket *avpkt)
{
    TDSCContext *ctx = avctx->priv_data;
    int ret, tag_header, keyframe = 0;
    uLongf dlen;

    /* Resize deflate buffer on resolution change */
    if (ctx->width != avctx->width || ctx->height != avctx->height) {
        int deflatelen = avctx->width * avctx->height * (3 + 1);
        if (deflatelen != ctx->deflatelen) {
            ctx->deflatelen =deflatelen;
            ret = av_reallocp(&ctx->deflatebuffer, ctx->deflatelen);
            if (ret < 0) {
                ctx->deflatelen = 0;
                return ret;
            }
        }
    }
    dlen = ctx->deflatelen;

    /* Frames are deflated, need to inflate them first */
    ret = uncompress(ctx->deflatebuffer, &dlen, avpkt->data, avpkt->size);
    if (ret) {
        av_log(avctx, AV_LOG_ERROR, "Deflate error %d.\n", ret);
        return AVERROR_UNKNOWN;
    }

    bytestream2_init(&ctx->gbc, ctx->deflatebuffer, dlen);

    /* Check for tag and for size info */
    if (bytestream2_get_bytes_left(&ctx->gbc) < 4 + 4) {
        av_log(avctx, AV_LOG_ERROR, "Frame is too small.\n");
        return AVERROR_INVALIDDATA;
    }

    /* Read tag */
    tag_header = bytestream2_get_le32(&ctx->gbc);

    if (tag_header == MKTAG('T','D','S','F')) {
        int number_tiles;
        if (bytestream2_get_bytes_left(&ctx->gbc) < TDSF_HEADER_SIZE) {
            av_log(avctx, AV_LOG_ERROR, "TDSF tag is too small.\n");
            return AVERROR_INVALIDDATA;
        }
        /* First 4 bytes here are the number of GEPJ/WAR tiles in this frame */
        number_tiles = bytestream2_get_le32(&ctx->gbc);

        bytestream2_skip(&ctx->gbc, 4); // internal timestamp maybe?
        keyframe = bytestream2_get_le32(&ctx->gbc) == 0x30;

        ret = tdsc_parse_tdsf(avctx, number_tiles);
        if (ret < 0)
            return ret;

        /* Check if there is anything else we are able to parse */
        if (bytestream2_get_bytes_left(&ctx->gbc) >= 4 + 4)
            tag_header = bytestream2_get_le32(&ctx->gbc);
    }

    /* This tag can be after a TDSF block or on its own frame */
    if (tag_header == MKTAG('D','T','S','M')) {
        /* First 4 bytes here are the total size in bytes for this frame */
        int tag_size = bytestream2_get_le32(&ctx->gbc);

        if (bytestream2_get_bytes_left(&ctx->gbc) < tag_size) {
            av_log(avctx, AV_LOG_ERROR, "DTSM tag is too small.\n");
            return AVERROR_INVALIDDATA;
        }

        ret = tdsc_parse_dtsm(avctx);
        if (ret < 0)
            return ret;
    }

    /* Get the output frame and copy the reference frame */
    ret = ff_get_buffer(avctx, frame, 0);
    if (ret < 0)
        return ret;

    ret = av_frame_copy(frame, ctx->refframe);
    if (ret < 0)
        return ret;

    /* Paint the cursor on the output frame */
    tdsc_paint_cursor(avctx, frame->data[0], frame->linesize[0]);

    /* Frame is ready to be output */
    if (keyframe) {
        frame->pict_type = AV_PICTURE_TYPE_I;
        frame->flags |= AV_FRAME_FLAG_KEY;
    } else {
        frame->pict_type = AV_PICTURE_TYPE_P;
    }
    *got_frame = 1;

    return avpkt->size;
}

const FFCodec ff_tdsc_decoder = {
    .p.name         = "tdsc",
    CODEC_LONG_NAME("TDSC"),
    .p.type         = AVMEDIA_TYPE_VIDEO,
    .p.id           = AV_CODEC_ID_TDSC,
    .init           = tdsc_init,
    FF_CODEC_DECODE_CB(tdsc_decode_frame),
    .close          = tdsc_close,
    .priv_data_size = sizeof(TDSCContext),
    .p.capabilities = AV_CODEC_CAP_DR1,
    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
};