aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/c93.c
blob: 9ac804ef72be798193cecd1cb892c5cfee64628b (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
/*
 * Interplay C93 video decoder
 * Copyright (c) 2007 Anssi Hannula <anssi.hannula@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
 */

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

typedef struct {
    AVFrame pictures[2];
    int currentpic;
} C93DecoderContext;

typedef enum {
    C93_8X8_FROM_PREV  = 0x02,
    C93_4X4_FROM_PREV  = 0x06,
    C93_4X4_FROM_CURR  = 0x07,
    C93_8X8_2COLOR     = 0x08,
    C93_4X4_2COLOR     = 0x0A,
    C93_4X4_4COLOR_GRP = 0x0B,
    C93_4X4_4COLOR     = 0x0D,
    C93_NOOP           = 0x0E,
    C93_8X8_INTRA      = 0x0F,
} C93BlockType;

#define WIDTH   320
#define HEIGHT  192

#define C93_HAS_PALETTE 0x01
#define C93_FIRST_FRAME 0x02

static av_cold int decode_init(AVCodecContext *avctx)
{
    C93DecoderContext *s = avctx->priv_data;
    avctx->pix_fmt = AV_PIX_FMT_PAL8;
    avcodec_get_frame_defaults(&s->pictures[0]);
    avcodec_get_frame_defaults(&s->pictures[1]);
    return 0;
}

static av_cold int decode_end(AVCodecContext *avctx)
{
    C93DecoderContext * const c93 = avctx->priv_data;

    av_frame_unref(&c93->pictures[0]);
    av_frame_unref(&c93->pictures[1]);

    return 0;
}

static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
        uint8_t *from, int offset, int height, int stride)
{
    int i;
    int width = height;
    int from_x = offset % WIDTH;
    int from_y = offset / WIDTH;
    int overflow = from_x + width - WIDTH;

    if (!from) {
        /* silently ignoring predictive blocks in first frame */
        return 0;
    }

    if (from_y + height > HEIGHT) {
        av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
               offset);
        return AVERROR_INVALIDDATA;
    }

    if (overflow > 0) {
        width -= overflow;
        for (i = 0; i < height; i++) {
            memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
        }
    }

    for (i = 0; i < height; i++) {
        memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
    }

    return 0;
}

static inline void draw_n_color(uint8_t *out, int stride, int width,
         int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
{
    int x, y;
    for (y = 0; y < height; y++) {
        if (grps)
            cols[0] = grps[3 * (y >> 1)];
        for (x = 0; x < width; x++) {
            if (grps)
                cols[1]= grps[(x >> 1) + 1];
            out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
            col >>= bpp;
        }
    }
}

static int decode_frame(AVCodecContext *avctx, void *data,
                        int *got_frame, AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    C93DecoderContext * const c93 = avctx->priv_data;
    AVFrame * const newpic = &c93->pictures[c93->currentpic];
    AVFrame * const oldpic = &c93->pictures[c93->currentpic^1];
    GetByteContext gb;
    uint8_t *out;
    int stride, ret, i, x, y, b, bt = 0;

    if ((ret = ff_set_dimensions(avctx, WIDTH, HEIGHT)) < 0)
        return ret;

    c93->currentpic ^= 1;

    if ((ret = ff_reget_buffer(avctx, newpic)) < 0)
        return ret;

    stride = newpic->linesize[0];

    bytestream2_init(&gb, buf, buf_size);
    b = bytestream2_get_byte(&gb);
    if (b & C93_FIRST_FRAME) {
        newpic->pict_type = AV_PICTURE_TYPE_I;
        newpic->key_frame = 1;
    } else {
        newpic->pict_type = AV_PICTURE_TYPE_P;
        newpic->key_frame = 0;
    }

    for (y = 0; y < HEIGHT; y += 8) {
        out = newpic->data[0] + y * stride;
        for (x = 0; x < WIDTH; x += 8) {
            uint8_t *copy_from = oldpic->data[0];
            unsigned int offset, j;
            uint8_t cols[4], grps[4];
            C93BlockType block_type;

            if (!bt)
                bt = bytestream2_get_byte(&gb);

            block_type= bt & 0x0F;
            switch (block_type) {
            case C93_8X8_FROM_PREV:
                offset = bytestream2_get_le16(&gb);
                if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
                    return ret;
                break;

            case C93_4X4_FROM_CURR:
                copy_from = newpic->data[0];
            case C93_4X4_FROM_PREV:
                for (j = 0; j < 8; j += 4) {
                    for (i = 0; i < 8; i += 4) {
                        int offset = bytestream2_get_le16(&gb);
                        int from_x = offset % WIDTH;
                        int from_y = offset / WIDTH;
                        if (block_type == C93_4X4_FROM_CURR && from_y == y+j &&
                            (FFABS(from_x - x-i) < 4 || FFABS(from_x - x-i) > WIDTH-4)) {
                            avpriv_request_sample(avctx, "block overlap %d %d %d %d\n", from_x, x+i, from_y, y+j);
                            return AVERROR_INVALIDDATA;
                        }
                        if ((ret = copy_block(avctx, &out[j*stride+i],
                                              copy_from, offset, 4, stride)) < 0)
                            return ret;
                    }
                }
                break;

            case C93_8X8_2COLOR:
                bytestream2_get_buffer(&gb, cols, 2);
                for (i = 0; i < 8; i++) {
                    draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
                                     NULL, bytestream2_get_byte(&gb));
                }

                break;

            case C93_4X4_2COLOR:
            case C93_4X4_4COLOR:
            case C93_4X4_4COLOR_GRP:
                for (j = 0; j < 8; j += 4) {
                    for (i = 0; i < 8; i += 4) {
                        if (block_type == C93_4X4_2COLOR) {
                            bytestream2_get_buffer(&gb, cols, 2);
                            draw_n_color(out + i + j*stride, stride, 4, 4,
                                    1, cols, NULL, bytestream2_get_le16(&gb));
                        } else if (block_type == C93_4X4_4COLOR) {
                            bytestream2_get_buffer(&gb, cols, 4);
                            draw_n_color(out + i + j*stride, stride, 4, 4,
                                    2, cols, NULL, bytestream2_get_le32(&gb));
                        } else {
                            bytestream2_get_buffer(&gb, grps, 4);
                            draw_n_color(out + i + j*stride, stride, 4, 4,
                                    1, cols, grps, bytestream2_get_le16(&gb));
                        }
                    }
                }
                break;

            case C93_NOOP:
                break;

            case C93_8X8_INTRA:
                for (j = 0; j < 8; j++)
                    bytestream2_get_buffer(&gb, out + j*stride, 8);
                break;

            default:
                av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
                       block_type, x, y);
                return AVERROR_INVALIDDATA;
            }
            bt >>= 4;
            out += 8;
        }
    }

    if (b & C93_HAS_PALETTE) {
        uint32_t *palette = (uint32_t *) newpic->data[1];
        for (i = 0; i < 256; i++) {
            palette[i] = 0xFFU << 24 | bytestream2_get_be24(&gb);
        }
        newpic->palette_has_changed = 1;
    } else {
        if (oldpic->data[1])
            memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
    }

    if ((ret = av_frame_ref(data, newpic)) < 0)
        return ret;
    *got_frame = 1;

    return buf_size;
}

AVCodec ff_c93_decoder = {
    .name           = "c93",
    .long_name      = NULL_IF_CONFIG_SMALL("Interplay C93"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_C93,
    .priv_data_size = sizeof(C93DecoderContext),
    .init           = decode_init,
    .close          = decode_end,
    .decode         = decode_frame,
    .capabilities   = CODEC_CAP_DR1,
};