FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/yop.c
Date: 2026-05-02 03:33:10
Exec Total Coverage
Lines: 83 101 82.2%
Functions: 6 6 100.0%
Branches: 30 44 68.2%
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1 /*
2 * Psygnosis YOP decoder
3 *
4 * Copyright (C) 2010 Mohamed Naufal Basheer <naufal11@gmail.com>
5 * derived from the code by
6 * Copyright (C) 2009 Thomas P. Higdon <thomas.p.higdon@gmail.com>
7 *
8 * This file is part of FFmpeg.
9 *
10 * FFmpeg is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU Lesser General Public
12 * License as published by the Free Software Foundation; either
13 * version 2.1 of the License, or (at your option) any later version.
14 *
15 * FFmpeg is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * Lesser General Public License for more details.
19 *
20 * You should have received a copy of the GNU Lesser General Public
21 * License along with FFmpeg; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 */
24
25 #include <string.h>
26
27 #include "libavutil/imgutils.h"
28 #include "libavutil/internal.h"
29
30 #include "avcodec.h"
31 #include "codec_internal.h"
32 #include "decode.h"
33
34 typedef struct YopDecContext {
35 AVCodecContext *avctx;
36 AVFrame *frame;
37
38 int num_pal_colors;
39 int first_color[2];
40 int frame_data_length;
41
42 const uint8_t *low_nibble;
43 const uint8_t *srcptr;
44 const uint8_t *src_end;
45 uint8_t *dstptr;
46 uint8_t *dstbuf;
47 } YopDecContext;
48
49 // These tables are taken directly from:
50 // http://wiki.multimedia.cx/index.php?title=Psygnosis_YOP
51
52 /**
53 * Lookup table for painting macroblocks. Bytes 0-2 of each entry contain
54 * the macroblock positions to be painted (taken as (0, B0, B1, B2)).
55 * Byte 3 contains the number of bytes consumed on the input,
56 * equal to max(bytes 0-2) + 1.
57 */
58 static const uint8_t paint_lut[15][4] =
59 {{1, 2, 3, 4}, {1, 2, 0, 3},
60 {1, 2, 1, 3}, {1, 2, 2, 3},
61 {1, 0, 2, 3}, {1, 0, 0, 2},
62 {1, 0, 1, 2}, {1, 1, 2, 3},
63 {0, 1, 2, 3}, {0, 1, 0, 2},
64 {1, 1, 0, 2}, {0, 1, 1, 2},
65 {0, 0, 1, 2}, {0, 0, 0, 1},
66 {1, 1, 1, 2},
67 };
68
69 /**
70 * Lookup table for copying macroblocks. Each entry contains the respective
71 * x and y pixel offset for the copy source.
72 */
73 static const int8_t motion_vector[16][2] =
74 {{-4, -4}, {-2, -4},
75 { 0, -4}, { 2, -4},
76 {-4, -2}, {-4, 0},
77 {-3, -3}, {-1, -3},
78 { 1, -3}, { 3, -3},
79 {-3, -1}, {-2, -2},
80 { 0, -2}, { 2, -2},
81 { 4, -2}, {-2, 0},
82 };
83
84 2 static av_cold int yop_decode_close(AVCodecContext *avctx)
85 {
86 2 YopDecContext *s = avctx->priv_data;
87
88 2 av_frame_free(&s->frame);
89
90 2 return 0;
91 }
92
93 2 static av_cold int yop_decode_init(AVCodecContext *avctx)
94 {
95 2 YopDecContext *s = avctx->priv_data;
96 2 s->avctx = avctx;
97
98
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 4 if (avctx->width & 1 || avctx->height & 1 ||
99 2 av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) {
100 ✗ av_log(avctx, AV_LOG_ERROR, "YOP has invalid dimensions\n");
101 ✗ return AVERROR_INVALIDDATA;
102 }
103
104
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 2 if (avctx->extradata_size < 3) {
105 ✗ av_log(avctx, AV_LOG_ERROR, "Missing or incomplete extradata.\n");
106 ✗ return AVERROR_INVALIDDATA;
107 }
108
109 2 avctx->pix_fmt = AV_PIX_FMT_PAL8;
110
111 2 s->num_pal_colors = avctx->extradata[0];
112 2 s->first_color[0] = avctx->extradata[1];
113 2 s->first_color[1] = avctx->extradata[2];
114
115
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 2 if (s->num_pal_colors + s->first_color[0] > 256 ||
116
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 2 s->num_pal_colors + s->first_color[1] > 256) {
117 ✗ av_log(avctx, AV_LOG_ERROR,
118 "Palette parameters invalid, header probably corrupt\n");
119 ✗ return AVERROR_INVALIDDATA;
120 }
121
122 2 s->frame = av_frame_alloc();
123
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 2 if (!s->frame)
124 ✗ return AVERROR(ENOMEM);
125
126 2 return 0;
127 }
128
129 /**
130 * Paint a macroblock using the pattern in paint_lut.
131 * @param s codec context
132 * @param tag the tag that was in the nibble
133 */
134 76866 static int yop_paint_block(YopDecContext *s, int linesize, int tag)
135 {
136
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 76866 if (s->src_end - s->srcptr < paint_lut[tag][3]) {
137 1 av_log(s->avctx, AV_LOG_ERROR, "Packet too small.\n");
138 1 return AVERROR_INVALIDDATA;
139 }
140
141 76865 s->dstptr[0] = s->srcptr[0];
142 76865 s->dstptr[1] = s->srcptr[paint_lut[tag][0]];
143 76865 s->dstptr[linesize] = s->srcptr[paint_lut[tag][1]];
144 76865 s->dstptr[linesize + 1] = s->srcptr[paint_lut[tag][2]];
145
146 // The number of src bytes consumed is in the last part of the lut entry.
147 76865 s->srcptr += paint_lut[tag][3];
148 76865 return 0;
149 }
150
151 /**
152 * Copy a previously painted macroblock to the current_block.
153 * @param copy_tag the tag that was in the nibble
154 */
155 90934 static int yop_copy_previous_block(YopDecContext *s, int linesize, int copy_tag)
156 {
157 uint8_t *bufptr;
158
159 // Calculate position for the copy source
160 90934 bufptr = s->dstptr + motion_vector[copy_tag][0] +
161 90934 linesize * motion_vector[copy_tag][1];
162
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 90934 if (bufptr < s->dstbuf) {
163 ✗ av_log(s->avctx, AV_LOG_ERROR, "File probably corrupt\n");
164 ✗ return AVERROR_INVALIDDATA;
165 }
166
167 90934 s->dstptr[0] = bufptr[0];
168 90934 s->dstptr[1] = bufptr[1];
169 90934 s->dstptr[linesize] = bufptr[linesize];
170 90934 s->dstptr[linesize + 1] = bufptr[linesize + 1];
171
172 90934 return 0;
173 }
174
175 /**
176 * Return the next nibble in sequence, consuming a new byte on the input
177 * only if necessary.
178 */
179 258734 static uint8_t yop_get_next_nibble(YopDecContext *s)
180 {
181 int ret;
182
183
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 258734 if (s->low_nibble) {
184 129365 ret = *s->low_nibble & 0xf;
185 129365 s->low_nibble = NULL;
186 }else {
187 129369 s->low_nibble = s->srcptr++;
188 129369 ret = *s->low_nibble >> 4;
189 }
190 258734 return ret;
191 }
192
193 7 static int yop_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
194 int *got_frame, AVPacket *avpkt)
195 {
196 7 YopDecContext *s = avctx->priv_data;
197 7 AVFrame *frame = s->frame;
198 int tag, firstcolor, is_odd_frame;
199 int ret, i, x, y;
200 uint32_t *palette;
201
202
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 7 if (avpkt->size < 4 + 3 * s->num_pal_colors) {
203 ✗ av_log(avctx, AV_LOG_ERROR, "Packet too small.\n");
204 ✗ return AVERROR_INVALIDDATA;
205 }
206
207
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 7 if ((ret = ff_reget_buffer(avctx, frame, 0)) < 0)
208 ✗ return ret;
209
210
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 7 if (!avctx->frame_num)
211 1 memset(frame->data[1], 0, AVPALETTE_SIZE);
212
213 7 s->dstbuf = frame->data[0];
214 7 s->dstptr = frame->data[0];
215 7 s->srcptr = avpkt->data + 4;
216 7 s->src_end = avpkt->data + avpkt->size;
217 7 s->low_nibble = NULL;
218
219 7 is_odd_frame = avpkt->data[0];
220
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 7 if(is_odd_frame>1){
221 ✗ av_log(avctx, AV_LOG_ERROR, "frame is too odd %d\n", is_odd_frame);
222 ✗ return AVERROR_INVALIDDATA;
223 }
224 7 firstcolor = s->first_color[is_odd_frame];
225 7 palette = (uint32_t *)frame->data[1];
226
227
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 847 for (i = 0; i < s->num_pal_colors; i++, s->srcptr += 3) {
228 840 palette[i + firstcolor] = (s->srcptr[0] << 18) |
229 840 (s->srcptr[1] << 10) |
230 840 (s->srcptr[2] << 2);
231 840 palette[i + firstcolor] |= 0xFFU << 24 |
232 840 (palette[i + firstcolor] >> 6) & 0x30303;
233 }
234
235
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 585 for (y = 0; y < avctx->height; y += 2) {
236
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 168378 for (x = 0; x < avctx->width; x += 2) {
237
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 167800 if (s->srcptr - avpkt->data >= avpkt->size) {
238 ✗ av_log(avctx, AV_LOG_ERROR, "Packet too small.\n");
239 ✗ return AVERROR_INVALIDDATA;
240 }
241
242 167800 tag = yop_get_next_nibble(s);
243
244
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 167800 if (tag != 0xf) {
245 76866 ret = yop_paint_block(s, frame->linesize[0], tag);
246
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 76866 if (ret < 0)
247 1 return ret;
248 } else {
249 90934 tag = yop_get_next_nibble(s);
250 90934 ret = yop_copy_previous_block(s, frame->linesize[0], tag);
251
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 90934 if (ret < 0)
252 ✗ return ret;
253 }
254 167799 s->dstptr += 2;
255 }
256 578 s->dstptr += 2*frame->linesize[0] - x;
257 }
258
259
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 6 if ((ret = av_frame_ref(rframe, s->frame)) < 0)
260 ✗ return ret;
261
262 6 *got_frame = 1;
263 6 return avpkt->size;
264 }
265
266 const FFCodec ff_yop_decoder = {
267 .p.name = "yop",
268 CODEC_LONG_NAME("Psygnosis YOP Video"),
269 .p.type = AVMEDIA_TYPE_VIDEO,
270 .p.id = AV_CODEC_ID_YOP,
271 .p.capabilities = AV_CODEC_CAP_DR1,
272 .priv_data_size = sizeof(YopDecContext),
273 .init = yop_decode_init,
274 .close = yop_decode_close,
275 FF_CODEC_DECODE_CB(yop_decode_frame),
276 };
277