FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/idcinvideo.c
Date: 2022-07-07 01:21:54
Exec Total Coverage
Lines: 75 81 92.6%
Branches: 32 36 88.9%

Line Branch Exec Source
1 /*
2 * id Quake II CIN Video Decoder
3 * Copyright (C) 2003 The FFmpeg project
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 /**
23 * @file
24 * id Quake II Cin Video Decoder by Dr. Tim Ferguson
25 * For more information about the id CIN format, visit:
26 * http://www.csse.monash.edu.au/~timf/
27 *
28 * This video decoder outputs PAL8 colorspace data. Interacting with this
29 * decoder is a little involved. During initialization, the demuxer must
30 * transmit the 65536-byte Huffman table(s) to the decoder via extradata.
31 * Then, whenever a palette change is encountered while demuxing the file,
32 * the demuxer must use the same extradata space to transmit an
33 * AVPaletteControl structure.
34 *
35 * id CIN video is purely Huffman-coded, intraframe-only codec. It achieves
36 * a little more compression by exploiting the fact that adjacent pixels
37 * tend to be similar.
38 *
39 * Note that this decoder could use libavcodec's optimized VLC facilities
40 * rather than naive, tree-based Huffman decoding. However, there are 256
41 * Huffman tables. Plus, the VLC bit coding order is right -> left instead
42 * or left -> right, so all of the bits would have to be reversed. Further,
43 * the original Quake II implementation likely used a similar naive
44 * decoding algorithm and it worked fine on much lower spec machines.
45 */
46
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <string.h>
50
51 #include "avcodec.h"
52 #include "codec_internal.h"
53 #include "decode.h"
54 #include "internal.h"
55 #include "libavutil/internal.h"
56
57 #define HUFFMAN_TABLE_SIZE 64 * 1024
58 #define HUF_TOKENS 256
59 #define PALETTE_COUNT 256
60
61 typedef struct hnode {
62 int count;
63 unsigned char used;
64 int children[2];
65 } hnode;
66
67 typedef struct IdcinContext {
68
69 AVCodecContext *avctx;
70
71 const unsigned char *buf;
72 int size;
73
74 hnode huff_nodes[256][HUF_TOKENS*2];
75 int num_huff_nodes[256];
76
77 uint32_t pal[256];
78 } IdcinContext;
79
80 /**
81 * Find the lowest probability node in a Huffman table, and mark it as
82 * being assigned to a higher probability.
83 * @return the node index of the lowest unused node, or -1 if all nodes
84 * are used.
85 */
86 36984 static int huff_smallest_node(hnode *hnodes, int num_hnodes) {
87 int i;
88 int best, best_node;
89
90 36984 best = 99999999;
91 36984 best_node = -1;
92
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10824952 for(i = 0; i < num_hnodes; i++) {
93
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10787968 if(hnodes[i].used)
94 2658518 continue;
95
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8129450 if(!hnodes[i].count)
96 6790996 continue;
97
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1338454 if(hnodes[i].count < best) {
98 132488 best = hnodes[i].count;
99 132488 best_node = i;
100 }
101 }
102
103
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36984 if(best_node == -1)
104 512 return -1;
105 36472 hnodes[best_node].used = 1;
106 36472 return best_node;
107 }
108
109 /*
110 * Build the Huffman tree using the generated/loaded probabilities histogram.
111 *
112 * On completion:
113 * huff_nodes[prev][i < HUF_TOKENS] - are the nodes at the base of the tree.
114 * huff_nodes[prev][i >= HUF_TOKENS] - are used to construct the tree.
115 * num_huff_nodes[prev] - contains the index to the root node of the tree.
116 * That is: huff_nodes[prev][num_huff_nodes[prev]] is the root node.
117 */
118 512 static av_cold void huff_build_tree(IdcinContext *s, int prev) {
119 hnode *node, *hnodes;
120 int num_hnodes, i;
121
122 512 num_hnodes = HUF_TOKENS;
123 512 hnodes = s->huff_nodes[prev];
124
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262656 for(i = 0; i < HUF_TOKENS * 2; i++)
125 262144 hnodes[i].used = 0;
126
127 while (1) {
128 18594 node = &hnodes[num_hnodes]; /* next free node */
129
130 /* pick two lowest counts */
131 18594 node->children[0] = huff_smallest_node(hnodes, num_hnodes);
132
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18594 if(node->children[0] == -1)
133 204 break; /* reached the root node */
134
135 18390 node->children[1] = huff_smallest_node(hnodes, num_hnodes);
136
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18390 if(node->children[1] == -1)
137 308 break; /* reached the root node */
138
139 /* combine nodes probability for new node */
140 18082 node->count = hnodes[node->children[0]].count +
141 18082 hnodes[node->children[1]].count;
142 18082 num_hnodes++;
143 }
144
145 512 s->num_huff_nodes[prev] = num_hnodes - 1;
146 512 }
147
148 2 static av_cold int idcin_decode_init(AVCodecContext *avctx)
149 {
150 2 IdcinContext *s = avctx->priv_data;
151 2 int i, j, histogram_index = 0;
152 unsigned char *histograms;
153
154 2 s->avctx = avctx;
155 2 avctx->pix_fmt = AV_PIX_FMT_PAL8;
156
157 /* make sure the Huffman tables make it */
158
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2 if (s->avctx->extradata_size != HUFFMAN_TABLE_SIZE) {
159 av_log(s->avctx, AV_LOG_ERROR, " id CIN video: expected extradata size of %d\n", HUFFMAN_TABLE_SIZE);
160 return -1;
161 }
162
163 /* build the 256 Huffman decode trees */
164 2 histograms = (unsigned char *)s->avctx->extradata;
165
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514 for (i = 0; i < 256; i++) {
166
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131584 for(j = 0; j < HUF_TOKENS; j++)
167 131072 s->huff_nodes[i][j].count = histograms[histogram_index++];
168 512 huff_build_tree(s, i);
169 }
170
171 2 return 0;
172 }
173
174 52 static int idcin_decode_vlcs(IdcinContext *s, AVFrame *frame)
175 {
176 hnode *hnodes;
177 long x, y;
178 int prev;
179 52 unsigned char v = 0;
180 int bit_pos, node_num, dat_pos;
181
182 52 prev = bit_pos = dat_pos = 0;
183
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12532 for (y = 0; y < (frame->linesize[0] * s->avctx->height);
184 12480 y += frame->linesize[0]) {
185
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4006080 for (x = y; x < y + s->avctx->width; x++) {
186 3993600 node_num = s->num_huff_nodes[prev];
187 3993600 hnodes = s->huff_nodes[prev];
188
189
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17457808 while(node_num >= HUF_TOKENS) {
190
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13464208 if(!bit_pos) {
191
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1683045 if(dat_pos >= s->size) {
192 av_log(s->avctx, AV_LOG_ERROR, "Huffman decode error.\n");
193 return -1;
194 }
195 1683045 bit_pos = 8;
196 1683045 v = s->buf[dat_pos++];
197 }
198
199 13464208 node_num = hnodes[node_num].children[v & 0x01];
200 13464208 v = v >> 1;
201 13464208 bit_pos--;
202 }
203
204 3993600 frame->data[0][x] = node_num;
205 3993600 prev = node_num;
206 }
207 }
208
209 52 return 0;
210 }
211
212 52 static int idcin_decode_frame(AVCodecContext *avctx, AVFrame *frame,
213 int *got_frame, AVPacket *avpkt)
214 {
215 52 const uint8_t *buf = avpkt->data;
216 52 int buf_size = avpkt->size;
217 52 IdcinContext *s = avctx->priv_data;
218 int ret;
219
220 52 s->buf = buf;
221 52 s->size = buf_size;
222
223
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52 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
224 return ret;
225
226
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52 if (idcin_decode_vlcs(s, frame))
227 return AVERROR_INVALIDDATA;
228
229 52 frame->palette_has_changed = ff_copy_palette(s->pal, avpkt, avctx);
230 /* make the palette available on the way out */
231 52 memcpy(frame->data[1], s->pal, AVPALETTE_SIZE);
232
233 52 *got_frame = 1;
234
235 /* report that the buffer was completely consumed */
236 52 return buf_size;
237 }
238
239 static const FFCodecDefault idcin_defaults[] = {
240 { "max_pixels", "320*240" },
241 { NULL },
242 };
243
244 const FFCodec ff_idcin_decoder = {
245 .p.name = "idcinvideo",
246 .p.long_name = NULL_IF_CONFIG_SMALL("id Quake II CIN video"),
247 .p.type = AVMEDIA_TYPE_VIDEO,
248 .p.id = AV_CODEC_ID_IDCIN,
249 .priv_data_size = sizeof(IdcinContext),
250 .init = idcin_decode_init,
251 FF_CODEC_DECODE_CB(idcin_decode_frame),
252 .p.capabilities = AV_CODEC_CAP_DR1,
253 .defaults = idcin_defaults,
254 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
255 };
256