FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/idcinvideo.c
Date: 2021-09-24 20:55:06
Exec Total Coverage
Lines: 76 82 92.7%
Branches: 32 36 88.9%

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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 "decode.h"
53 #include "internal.h"
54 #include "libavutil/internal.h"
55
56 #define HUFFMAN_TABLE_SIZE 64 * 1024
57 #define HUF_TOKENS 256
58 #define PALETTE_COUNT 256
59
60 typedef struct hnode {
61 int count;
62 unsigned char used;
63 int children[2];
64 } hnode;
65
66 typedef struct IdcinContext {
67
68 AVCodecContext *avctx;
69
70 const unsigned char *buf;
71 int size;
72
73 hnode huff_nodes[256][HUF_TOKENS*2];
74 int num_huff_nodes[256];
75
76 uint32_t pal[256];
77 } IdcinContext;
78
79 /**
80 * Find the lowest probability node in a Huffman table, and mark it as
81 * being assigned to a higher probability.
82 * @return the node index of the lowest unused node, or -1 if all nodes
83 * are used.
84 */
85 36984 static int huff_smallest_node(hnode *hnodes, int num_hnodes) {
86 int i;
87 int best, best_node;
88
89 36984 best = 99999999;
90 36984 best_node = -1;
91
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10824952 for(i = 0; i < num_hnodes; i++) {
92
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10787968 if(hnodes[i].used)
93 2658518 continue;
94
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8129450 if(!hnodes[i].count)
95 6790996 continue;
96
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1338454 if(hnodes[i].count < best) {
97 132488 best = hnodes[i].count;
98 132488 best_node = i;
99 }
100 }
101
102
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36984 if(best_node == -1)
103 512 return -1;
104 36472 hnodes[best_node].used = 1;
105 36472 return best_node;
106 }
107
108 /*
109 * Build the Huffman tree using the generated/loaded probabilities histogram.
110 *
111 * On completion:
112 * huff_nodes[prev][i < HUF_TOKENS] - are the nodes at the base of the tree.
113 * huff_nodes[prev][i >= HUF_TOKENS] - are used to construct the tree.
114 * num_huff_nodes[prev] - contains the index to the root node of the tree.
115 * That is: huff_nodes[prev][num_huff_nodes[prev]] is the root node.
116 */
117 512 static av_cold void huff_build_tree(IdcinContext *s, int prev) {
118 hnode *node, *hnodes;
119 int num_hnodes, i;
120
121 512 num_hnodes = HUF_TOKENS;
122 512 hnodes = s->huff_nodes[prev];
123
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262656 for(i = 0; i < HUF_TOKENS * 2; i++)
124 262144 hnodes[i].used = 0;
125
126 while (1) {
127 18594 node = &hnodes[num_hnodes]; /* next free node */
128
129 /* pick two lowest counts */
130 18594 node->children[0] = huff_smallest_node(hnodes, num_hnodes);
131
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18594 if(node->children[0] == -1)
132 204 break; /* reached the root node */
133
134 18390 node->children[1] = huff_smallest_node(hnodes, num_hnodes);
135
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18390 if(node->children[1] == -1)
136 308 break; /* reached the root node */
137
138 /* combine nodes probability for new node */
139 18082 node->count = hnodes[node->children[0]].count +
140 18082 hnodes[node->children[1]].count;
141 18082 num_hnodes++;
142 }
143
144 512 s->num_huff_nodes[prev] = num_hnodes - 1;
145 512 }
146
147 2 static av_cold int idcin_decode_init(AVCodecContext *avctx)
148 {
149 2 IdcinContext *s = avctx->priv_data;
150 2 int i, j, histogram_index = 0;
151 unsigned char *histograms;
152
153 2 s->avctx = avctx;
154 2 avctx->pix_fmt = AV_PIX_FMT_PAL8;
155
156 /* make sure the Huffman tables make it */
157
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2 if (s->avctx->extradata_size != HUFFMAN_TABLE_SIZE) {
158 av_log(s->avctx, AV_LOG_ERROR, " id CIN video: expected extradata size of %d\n", HUFFMAN_TABLE_SIZE);
159 return -1;
160 }
161
162 /* build the 256 Huffman decode trees */
163 2 histograms = (unsigned char *)s->avctx->extradata;
164
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514 for (i = 0; i < 256; i++) {
165
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131584 for(j = 0; j < HUF_TOKENS; j++)
166 131072 s->huff_nodes[i][j].count = histograms[histogram_index++];
167 512 huff_build_tree(s, i);
168 }
169
170 2 return 0;
171 }
172
173 52 static int idcin_decode_vlcs(IdcinContext *s, AVFrame *frame)
174 {
175 hnode *hnodes;
176 long x, y;
177 int prev;
178 52 unsigned char v = 0;
179 int bit_pos, node_num, dat_pos;
180
181 52 prev = bit_pos = dat_pos = 0;
182
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12532 for (y = 0; y < (frame->linesize[0] * s->avctx->height);
183 12480 y += frame->linesize[0]) {
184
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4006080 for (x = y; x < y + s->avctx->width; x++) {
185 3993600 node_num = s->num_huff_nodes[prev];
186 3993600 hnodes = s->huff_nodes[prev];
187
188
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17457808 while(node_num >= HUF_TOKENS) {
189
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13464208 if(!bit_pos) {
190
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1683045 if(dat_pos >= s->size) {
191 av_log(s->avctx, AV_LOG_ERROR, "Huffman decode error.\n");
192 return -1;
193 }
194 1683045 bit_pos = 8;
195 1683045 v = s->buf[dat_pos++];
196 }
197
198 13464208 node_num = hnodes[node_num].children[v & 0x01];
199 13464208 v = v >> 1;
200 13464208 bit_pos--;
201 }
202
203 3993600 frame->data[0][x] = node_num;
204 3993600 prev = node_num;
205 }
206 }
207
208 52 return 0;
209 }
210
211 52 static int idcin_decode_frame(AVCodecContext *avctx,
212 void *data, int *got_frame,
213 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 52 AVFrame *frame = data;
219 int ret;
220
221 52 s->buf = buf;
222 52 s->size = buf_size;
223
224
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52 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
225 return ret;
226
227
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52 if (idcin_decode_vlcs(s, frame))
228 return AVERROR_INVALIDDATA;
229
230 52 frame->palette_has_changed = ff_copy_palette(s->pal, avpkt, avctx);
231 /* make the palette available on the way out */
232 52 memcpy(frame->data[1], s->pal, AVPALETTE_SIZE);
233
234 52 *got_frame = 1;
235
236 /* report that the buffer was completely consumed */
237 52 return buf_size;
238 }
239
240 static const AVCodecDefault idcin_defaults[] = {
241 { "max_pixels", "320*240" },
242 { NULL },
243 };
244
245 const AVCodec ff_idcin_decoder = {
246 .name = "idcinvideo",
247 .long_name = NULL_IF_CONFIG_SMALL("id Quake II CIN video"),
248 .type = AVMEDIA_TYPE_VIDEO,
249 .id = AV_CODEC_ID_IDCIN,
250 .priv_data_size = sizeof(IdcinContext),
251 .init = idcin_decode_init,
252 .decode = idcin_decode_frame,
253 .capabilities = AV_CODEC_CAP_DR1,
254 .defaults = idcin_defaults,
255 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
256 };
257