FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/c93.c
Date: 2025-11-03 14:06:37
Exec Total Coverage
Lines: 106 126 84.1%
Functions: 5 5 100.0%
Branches: 58 80 72.5%
Line Branch Exec Source
1 /*
2 * Interplay C93 video decoder
3 * Copyright (c) 2007 Anssi Hannula <anssi.hannula@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 *
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 #include "avcodec.h"
23 #include "bytestream.h"
24 #include "codec_internal.h"
25 #include "decode.h"
26
27 typedef struct C93DecoderContext {
28 AVFrame *pictures[2];
29 int currentpic;
30 } C93DecoderContext;
31
32 typedef enum {
33 C93_8X8_FROM_PREV = 0x02,
34 C93_4X4_FROM_PREV = 0x06,
35 C93_4X4_FROM_CURR = 0x07,
36 C93_8X8_2COLOR = 0x08,
37 C93_4X4_2COLOR = 0x0A,
38 C93_4X4_4COLOR_GRP = 0x0B,
39 C93_4X4_4COLOR = 0x0D,
40 C93_NOOP = 0x0E,
41 C93_8X8_INTRA = 0x0F,
42 } C93BlockType;
43
44 #define WIDTH 320
45 #define HEIGHT 192
46
47 #define C93_HAS_PALETTE 0x01
48 #define C93_FIRST_FRAME 0x02
49
50 2 static av_cold int decode_end(AVCodecContext *avctx)
51 {
52 2 C93DecoderContext * const c93 = avctx->priv_data;
53
54 2 av_frame_free(&c93->pictures[0]);
55 2 av_frame_free(&c93->pictures[1]);
56
57 2 return 0;
58 }
59
60 2 static av_cold int decode_init(AVCodecContext *avctx)
61 {
62 2 C93DecoderContext *s = avctx->priv_data;
63 2 avctx->pix_fmt = AV_PIX_FMT_PAL8;
64
65 2 s->pictures[0] = av_frame_alloc();
66 2 s->pictures[1] = av_frame_alloc();
67
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 2 if (!s->pictures[0] || !s->pictures[1])
68 ✗ return AVERROR(ENOMEM);
69
70 2 return 0;
71 }
72
73 91637 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
74 uint8_t *from, int offset, int height, int stride)
75 {
76 int i;
77 91637 int width = height;
78 91637 int from_x = offset % WIDTH;
79 91637 int from_y = offset / WIDTH;
80 91637 int overflow = from_x + width - WIDTH;
81
82
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 91637 if (!from) {
83 /* silently ignoring predictive blocks in first frame */
84 ✗ return 0;
85 }
86
87
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 91637 if (from_y + height > HEIGHT) {
88 ✗ av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
89 offset);
90 ✗ return AVERROR_INVALIDDATA;
91 }
92
93
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 91637 if (overflow > 0) {
94 ✗ width -= overflow;
95 ✗ for (i = 0; i < height; i++) {
96 ✗ memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
97 }
98 }
99
100
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 535069 for (i = 0; i < height; i++) {
101 443432 memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
102 }
103
104 91637 return 0;
105 }
106
107 2488 static inline void draw_n_color(uint8_t *out, int stride, int width,
108 int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
109 {
110 int x, y;
111
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 11144 for (y = 0; y < height; y++) {
112
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 8656 if (grps)
113 480 cols[0] = grps[3 * (y >> 1)];
114
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 45008 for (x = 0; x < width; x++) {
115
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 36352 if (grps)
116 1920 cols[1]= grps[(x >> 1) + 1];
117 36352 out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
118 36352 col >>= bpp;
119 }
120 }
121 2488 }
122
123 42 static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
124 int *got_frame, AVPacket *avpkt)
125 {
126 42 const uint8_t *buf = avpkt->data;
127 42 int buf_size = avpkt->size;
128 42 C93DecoderContext * const c93 = avctx->priv_data;
129 42 AVFrame * const newpic = c93->pictures[c93->currentpic];
130 42 AVFrame * const oldpic = c93->pictures[c93->currentpic^1];
131 GetByteContext gb;
132 uint8_t *out;
133 42 int ret, i, x, y, b, bt = 0;
134 ptrdiff_t stride;
135
136
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 42 if ((ret = ff_set_dimensions(avctx, WIDTH, HEIGHT)) < 0)
137 ✗ return ret;
138
139 42 c93->currentpic ^= 1;
140
141
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 42 if ((ret = ff_reget_buffer(avctx, newpic, 0)) < 0)
142 ✗ return ret;
143
144 42 stride = newpic->linesize[0];
145
146 42 bytestream2_init(&gb, buf, buf_size);
147 42 b = bytestream2_get_byte(&gb);
148
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 42 if (b & C93_FIRST_FRAME) {
149 1 newpic->pict_type = AV_PICTURE_TYPE_I;
150 1 newpic->flags |= AV_FRAME_FLAG_KEY;
151 } else {
152 41 newpic->pict_type = AV_PICTURE_TYPE_P;
153 41 newpic->flags &= ~AV_FRAME_FLAG_KEY;
154 }
155
156
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 1050 for (y = 0; y < HEIGHT; y += 8) {
157 1008 out = newpic->data[0] + y * stride;
158
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 41328 for (x = 0; x < WIDTH; x += 8) {
159 40320 uint8_t *copy_from = oldpic->data[0];
160 uint8_t cols[4], grps[4];
161 C93BlockType block_type;
162
163
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 40320 if (!bt)
164 20160 bt = bytestream2_get_byte(&gb);
165
166 40320 block_type= bt & 0x0F;
167
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 40320 switch (block_type) {
168 19221 case C93_8X8_FROM_PREV: {
169 19221 int offset = bytestream2_get_le16(&gb);
170
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 19221 if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
171 ✗ return ret;
172 19221 break;
173 }
174
175 621 case C93_4X4_FROM_CURR:
176 621 copy_from = newpic->data[0];
177 18104 case C93_4X4_FROM_PREV:
178
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 54312 for (int j = 0; j < 8; j += 4) {
179
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 108624 for (i = 0; i < 8; i += 4) {
180 72416 int offset = bytestream2_get_le16(&gb);
181 72416 int from_x = offset % WIDTH;
182 72416 int from_y = offset / WIDTH;
183
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 72416 if (block_type == C93_4X4_FROM_CURR && from_y == y+j &&
184 ✗ (FFABS(from_x - x-i) < 4 || FFABS(from_x - x-i) > WIDTH-4)) {
185 ✗ avpriv_request_sample(avctx, "block overlap %d %d %d %d", from_x, x+i, from_y, y+j);
186 ✗ return AVERROR_INVALIDDATA;
187 }
188
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 72416 if ((ret = copy_block(avctx, &out[j*stride+i],
189 copy_from, offset, 4, stride)) < 0)
190 ✗ return ret;
191 }
192 }
193 18104 break;
194
195 54 case C93_8X8_2COLOR:
196 54 bytestream2_get_buffer(&gb, cols, 2);
197
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 486 for (i = 0; i < 8; i++) {
198 432 draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
199 NULL, bytestream2_get_byte(&gb));
200 }
201
202 54 break;
203
204 514 case C93_4X4_2COLOR:
205 case C93_4X4_4COLOR:
206 case C93_4X4_4COLOR_GRP:
207
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 1542 for (int j = 0; j < 8; j += 4) {
208
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 3084 for (i = 0; i < 8; i += 4) {
209
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 2056 if (block_type == C93_4X4_2COLOR) {
210 104 bytestream2_get_buffer(&gb, cols, 2);
211 104 draw_n_color(out + i + j*stride, stride, 4, 4,
212 1, cols, NULL, bytestream2_get_le16(&gb));
213
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 1952 } else if (block_type == C93_4X4_4COLOR) {
214 1832 bytestream2_get_buffer(&gb, cols, 4);
215 1832 draw_n_color(out + i + j*stride, stride, 4, 4,
216 2, cols, NULL, bytestream2_get_le32(&gb));
217 } else {
218 120 bytestream2_get_buffer(&gb, grps, 4);
219 120 draw_n_color(out + i + j*stride, stride, 4, 4,
220 1, cols, grps, bytestream2_get_le16(&gb));
221 }
222 }
223 }
224 514 break;
225
226 ✗ case C93_NOOP:
227 ✗ break;
228
229 2427 case C93_8X8_INTRA:
230
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 21843 for (int j = 0; j < 8; j++)
231 19416 bytestream2_get_buffer(&gb, out + j*stride, 8);
232 2427 break;
233
234 ✗ default:
235 ✗ av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
236 block_type, x, y);
237 ✗ return AVERROR_INVALIDDATA;
238 }
239 40320 bt >>= 4;
240 40320 out += 8;
241 }
242 }
243
244
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 42 if (b & C93_HAS_PALETTE) {
245 1 uint32_t *palette = (uint32_t *) newpic->data[1];
246
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 257 for (i = 0; i < 256; i++) {
247 256 palette[i] = 0xFFU << 24 | bytestream2_get_be24(&gb);
248 }
249 } else {
250
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 41 if (oldpic->data[1])
251 41 memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
252 }
253
254
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 42 if ((ret = av_frame_ref(rframe, newpic)) < 0)
255 ✗ return ret;
256 42 *got_frame = 1;
257
258 42 return buf_size;
259 }
260
261 const FFCodec ff_c93_decoder = {
262 .p.name = "c93",
263 CODEC_LONG_NAME("Interplay C93"),
264 .p.type = AVMEDIA_TYPE_VIDEO,
265 .p.id = AV_CODEC_ID_C93,
266 .priv_data_size = sizeof(C93DecoderContext),
267 .init = decode_init,
268 .close = decode_end,
269 FF_CODEC_DECODE_CB(decode_frame),
270 .p.capabilities = AV_CODEC_CAP_DR1,
271 .caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
272 };
273