8ce045dc0f814d8150480afbc8be96a1f5e23828
[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 #include "internal.h"
53 #include "libavutil/internal.h"
54
55 #define HUFFMAN_TABLE_SIZE 64 * 1024
56 #define HUF_TOKENS 256
57 #define PALETTE_COUNT 256
58
59 typedef struct
60 {
61 int count;
62 unsigned char used;
63 int children[2];
64 } hnode;
65
66 typedef struct IdcinContext {
67
68 AVCodecContext *avctx;
69 AVFrame frame;
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 static int huff_smallest_node(hnode *hnodes, int num_hnodes) {
87 int i;
88 int best, best_node;
89
90 best = 99999999;
91 best_node = -1;
92 for(i = 0; i < num_hnodes; i++) {
93 if(hnodes[i].used)
94 continue;
95 if(!hnodes[i].count)
96 continue;
97 if(hnodes[i].count < best) {
98 best = hnodes[i].count;
99 best_node = i;
100 }
101 }
102
103 if(best_node == -1)
104 return -1;
105 hnodes[best_node].used = 1;
106 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 static av_cold void huff_build_tree(IdcinContext *s, int prev) {
119 hnode *node, *hnodes;
120 int num_hnodes, i;
121
122 num_hnodes = HUF_TOKENS;
123 hnodes = s->huff_nodes[prev];
124 for(i = 0; i < HUF_TOKENS * 2; i++)
125 hnodes[i].used = 0;
126
127 while (1) {
128 node = &hnodes[num_hnodes]; /* next free node */
129
130 /* pick two lowest counts */
131 node->children[0] = huff_smallest_node(hnodes, num_hnodes);
132 if(node->children[0] == -1)
133 break; /* reached the root node */
134
135 node->children[1] = huff_smallest_node(hnodes, num_hnodes);
136 if(node->children[1] == -1)
137 break; /* reached the root node */
138
139 /* combine nodes probability for new node */
140 node->count = hnodes[node->children[0]].count +
141 hnodes[node->children[1]].count;
142 num_hnodes++;
143 }
144
145 s->num_huff_nodes[prev] = num_hnodes - 1;
146 }
147
148 static av_cold int idcin_decode_init(AVCodecContext *avctx)
149 {
150 IdcinContext *s = avctx->priv_data;
151 int i, j, histogram_index = 0;
152 unsigned char *histograms;
153
154 s->avctx = avctx;
155 avctx->pix_fmt = AV_PIX_FMT_PAL8;
156
157 /* make sure the Huffman tables make it */
158 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 histograms = (unsigned char *)s->avctx->extradata;
165 for (i = 0; i < 256; i++) {
166 for(j = 0; j < HUF_TOKENS; j++)
167 s->huff_nodes[i][j].count = histograms[histogram_index++];
168 huff_build_tree(s, i);
169 }
170
171 s->frame.data[0] = NULL;
172
173 return 0;
174 }
175
176 static void idcin_decode_vlcs(IdcinContext *s)
177 {
178 hnode *hnodes;
179 long x, y;
180 int prev;
181 unsigned char v = 0;
182 int bit_pos, node_num, dat_pos;
183
184 prev = bit_pos = dat_pos = 0;
185 for (y = 0; y < (s->frame.linesize[0] * s->avctx->height);
186 y += s->frame.linesize[0]) {
187 for (x = y; x < y + s->avctx->width; x++) {
188 node_num = s->num_huff_nodes[prev];
189 hnodes = s->huff_nodes[prev];
190
191 while(node_num >= HUF_TOKENS) {
192 if(!bit_pos) {
193 if(dat_pos >= s->size) {
194 av_log(s->avctx, AV_LOG_ERROR, "Huffman decode error.\n");
195 return;
196 }
197 bit_pos = 8;
198 v = s->buf[dat_pos++];
199 }
200
201 node_num = hnodes[node_num].children[v & 0x01];
202 v = v >> 1;
203 bit_pos--;
204 }
205
206 s->frame.data[0][x] = node_num;
207 prev = node_num;
208 }
209 }
210 }
211
212 static int idcin_decode_frame(AVCodecContext *avctx,
213 void *data, int *data_size,
214 AVPacket *avpkt)
215 {
216 const uint8_t *buf = avpkt->data;
217 int buf_size = avpkt->size;
218 IdcinContext *s = avctx->priv_data;
219 const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, NULL);
220
221 s->buf = buf;
222 s->size = buf_size;
223
224 if (s->frame.data[0])
225 avctx->release_buffer(avctx, &s->frame);
226
227 if (ff_get_buffer(avctx, &s->frame)) {
228 av_log(avctx, AV_LOG_ERROR, " id CIN Video: get_buffer() failed\n");
229 return -1;
230 }
231
232 idcin_decode_vlcs(s);
233
234 if (pal) {
235 s->frame.palette_has_changed = 1;
236 memcpy(s->pal, pal, AVPALETTE_SIZE);
237 }
238 /* make the palette available on the way out */
239 memcpy(s->frame.data[1], s->pal, AVPALETTE_SIZE);
240
241 *data_size = sizeof(AVFrame);
242 *(AVFrame*)data = s->frame;
243
244 /* report that the buffer was completely consumed */
245 return buf_size;
246 }
247
248 static av_cold int idcin_decode_end(AVCodecContext *avctx)
249 {
250 IdcinContext *s = avctx->priv_data;
251
252 if (s->frame.data[0])
253 avctx->release_buffer(avctx, &s->frame);
254
255 return 0;
256 }
257
258 AVCodec ff_idcin_decoder = {
259 .name = "idcinvideo",
260 .type = AVMEDIA_TYPE_VIDEO,
261 .id = AV_CODEC_ID_IDCIN,
262 .priv_data_size = sizeof(IdcinContext),
263 .init = idcin_decode_init,
264 .close = idcin_decode_end,
265 .decode = idcin_decode_frame,
266 .capabilities = CODEC_CAP_DR1,
267 .long_name = NULL_IF_CONFIG_SMALL("id Quake II CIN video"),
268 };