e1b0e2e3e9ff2dfa9bcd37480f7b207bd9cd532e
[libav.git] / libavcodec / idcinvideo.c
1 /*
2 * id Quake II CIN Video Decoder
3 * Copyright (C) 2003 the ffmpeg project
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; 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
53 #define HUFFMAN_TABLE_SIZE 64 * 1024
54 #define HUF_TOKENS 256
55 #define PALETTE_COUNT 256
56
57 typedef struct
58 {
59 int count;
60 unsigned char used;
61 int children[2];
62 } hnode;
63
64 typedef struct IdcinContext {
65
66 AVCodecContext *avctx;
67 AVFrame frame;
68
69 const unsigned char *buf;
70 int size;
71
72 hnode huff_nodes[256][HUF_TOKENS*2];
73 int num_huff_nodes[256];
74
75 uint32_t pal[256];
76 } IdcinContext;
77
78 /*
79 * Find the lowest probability node in a Huffman table, and mark it as
80 * being assigned to a higher probability.
81 * @return the node index of the lowest unused node, or -1 if all nodes
82 * are used.
83 */
84 static int huff_smallest_node(hnode *hnodes, int num_hnodes) {
85 int i;
86 int best, best_node;
87
88 best = 99999999;
89 best_node = -1;
90 for(i = 0; i < num_hnodes; i++) {
91 if(hnodes[i].used)
92 continue;
93 if(!hnodes[i].count)
94 continue;
95 if(hnodes[i].count < best) {
96 best = hnodes[i].count;
97 best_node = i;
98 }
99 }
100
101 if(best_node == -1)
102 return -1;
103 hnodes[best_node].used = 1;
104 return best_node;
105 }
106
107 /*
108 * Build the Huffman tree using the generated/loaded probabilities histogram.
109 *
110 * On completion:
111 * huff_nodes[prev][i < HUF_TOKENS] - are the nodes at the base of the tree.
112 * huff_nodes[prev][i >= HUF_TOKENS] - are used to construct the tree.
113 * num_huff_nodes[prev] - contains the index to the root node of the tree.
114 * That is: huff_nodes[prev][num_huff_nodes[prev]] is the root node.
115 */
116 static av_cold void huff_build_tree(IdcinContext *s, int prev) {
117 hnode *node, *hnodes;
118 int num_hnodes, i;
119
120 num_hnodes = HUF_TOKENS;
121 hnodes = s->huff_nodes[prev];
122 for(i = 0; i < HUF_TOKENS * 2; i++)
123 hnodes[i].used = 0;
124
125 while (1) {
126 node = &hnodes[num_hnodes]; /* next free node */
127
128 /* pick two lowest counts */
129 node->children[0] = huff_smallest_node(hnodes, num_hnodes);
130 if(node->children[0] == -1)
131 break; /* reached the root node */
132
133 node->children[1] = huff_smallest_node(hnodes, num_hnodes);
134 if(node->children[1] == -1)
135 break; /* reached the root node */
136
137 /* combine nodes probability for new node */
138 node->count = hnodes[node->children[0]].count +
139 hnodes[node->children[1]].count;
140 num_hnodes++;
141 }
142
143 s->num_huff_nodes[prev] = num_hnodes - 1;
144 }
145
146 static av_cold int idcin_decode_init(AVCodecContext *avctx)
147 {
148 IdcinContext *s = avctx->priv_data;
149 int i, j, histogram_index = 0;
150 unsigned char *histograms;
151
152 s->avctx = avctx;
153 avctx->pix_fmt = PIX_FMT_PAL8;
154
155 /* make sure the Huffman tables make it */
156 if (s->avctx->extradata_size != HUFFMAN_TABLE_SIZE) {
157 av_log(s->avctx, AV_LOG_ERROR, " id CIN video: expected extradata size of %d\n", HUFFMAN_TABLE_SIZE);
158 return -1;
159 }
160
161 /* build the 256 Huffman decode trees */
162 histograms = (unsigned char *)s->avctx->extradata;
163 for (i = 0; i < 256; i++) {
164 for(j = 0; j < HUF_TOKENS; j++)
165 s->huff_nodes[i][j].count = histograms[histogram_index++];
166 huff_build_tree(s, i);
167 }
168
169 s->frame.data[0] = NULL;
170
171 return 0;
172 }
173
174 static void idcin_decode_vlcs(IdcinContext *s)
175 {
176 hnode *hnodes;
177 long x, y;
178 int prev;
179 unsigned char v = 0;
180 int bit_pos, node_num, dat_pos;
181
182 prev = bit_pos = dat_pos = 0;
183 for (y = 0; y < (s->frame.linesize[0] * s->avctx->height);
184 y += s->frame.linesize[0]) {
185 for (x = y; x < y + s->avctx->width; x++) {
186 node_num = s->num_huff_nodes[prev];
187 hnodes = s->huff_nodes[prev];
188
189 while(node_num >= HUF_TOKENS) {
190 if(!bit_pos) {
191 if(dat_pos >= s->size) {
192 av_log(s->avctx, AV_LOG_ERROR, "Huffman decode error.\n");
193 return;
194 }
195 bit_pos = 8;
196 v = s->buf[dat_pos++];
197 }
198
199 node_num = hnodes[node_num].children[v & 0x01];
200 v = v >> 1;
201 bit_pos--;
202 }
203
204 s->frame.data[0][x] = node_num;
205 prev = node_num;
206 }
207 }
208 }
209
210 static int idcin_decode_frame(AVCodecContext *avctx,
211 void *data, int *data_size,
212 AVPacket *avpkt)
213 {
214 const uint8_t *buf = avpkt->data;
215 int buf_size = avpkt->size;
216 IdcinContext *s = avctx->priv_data;
217 const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, NULL);
218
219 s->buf = buf;
220 s->size = buf_size;
221
222 if (s->frame.data[0])
223 avctx->release_buffer(avctx, &s->frame);
224
225 if (avctx->get_buffer(avctx, &s->frame)) {
226 av_log(avctx, AV_LOG_ERROR, " id CIN Video: get_buffer() failed\n");
227 return -1;
228 }
229
230 idcin_decode_vlcs(s);
231
232 if (pal) {
233 s->frame.palette_has_changed = 1;
234 memcpy(s->pal, pal, AVPALETTE_SIZE);
235 }
236 /* make the palette available on the way out */
237 memcpy(s->frame.data[1], s->pal, AVPALETTE_SIZE);
238
239 *data_size = sizeof(AVFrame);
240 *(AVFrame*)data = s->frame;
241
242 /* report that the buffer was completely consumed */
243 return buf_size;
244 }
245
246 static av_cold int idcin_decode_end(AVCodecContext *avctx)
247 {
248 IdcinContext *s = avctx->priv_data;
249
250 if (s->frame.data[0])
251 avctx->release_buffer(avctx, &s->frame);
252
253 return 0;
254 }
255
256 AVCodec ff_idcin_decoder = {
257 .name = "idcinvideo",
258 .type = AVMEDIA_TYPE_VIDEO,
259 .id = CODEC_ID_IDCIN,
260 .priv_data_size = sizeof(IdcinContext),
261 .init = idcin_decode_init,
262 .close = idcin_decode_end,
263 .decode = idcin_decode_frame,
264 .capabilities = CODEC_CAP_DR1,
265 .long_name = NULL_IF_CONFIG_SMALL("id Quake II CIN video"),
266 };