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
54
55 #define HUFFMAN_TABLE_SIZE 64 * 1024
56 #define HUF_TOKENS 256
57 #define PALETTE_COUNT 256
58
64
66
68
69 const unsigned char *
buf;
71
74
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 */
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;
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 */
117 hnode *node, *hnodes;
118 int num_hnodes, i;
119
123 hnodes[i].used = 0;
124
125 while (1) {
126 node = &hnodes[num_hnodes]; /* next free node */
127
128 /* pick two lowest counts */
131 break; /* reached the root node */
132
135 break; /* reached the root node */
136
137 /* combine nodes probability for new node */
140 num_hnodes++;
141 }
142
144 }
145
147 {
149 int i, j, histogram_index = 0;
150 unsigned char *histograms;
151
154
155 /* make sure the Huffman tables make it */
158 return -1;
159 }
160
161 /* build the 256 Huffman decode trees */
163 for (i = 0; i < 256; i++) {
167 }
168
169 return 0;
170 }
171
173 {
175 long x, y;
176 int prev;
177 unsigned char v = 0;
178 int bit_pos, node_num, dat_pos;
179
180 prev = bit_pos = dat_pos = 0;
186
188 if(!bit_pos) {
189 if(dat_pos >= s->
size) {
191 return -1;
192 }
193 bit_pos = 8;
194 v = s->
buf[dat_pos++];
195 }
196
197 node_num = hnodes[node_num].
children[v & 0x01];
198 v = v >> 1;
199 bit_pos--;
200 }
201
202 frame->
data[0][x] = node_num;
203 prev = node_num;
204 }
205 }
206
207 return 0;
208 }
209
211 void *
data,
int *got_frame,
213 {
215 int buf_size = avpkt->
size;
217 int pal_size;
220 int ret;
221
224
226 return ret;
227
230
234 } else if (pal) {
236 }
237 /* make the palette available on the way out */
239
240 *got_frame = 1;
241
242 /* report that the buffer was completely consumed */
243 return buf_size;
244 }
245
247 .
name =
"idcinvideo",
255 };
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
This structure describes decoded (raw) audio or video data.
ptrdiff_t const GLvoid * data
static av_cold int init(AVCodecContext *avctx)
static int idcin_decode_vlcs(IdcinContext *s, AVFrame *frame)
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
8 bits with AV_PIX_FMT_RGB32 palette
uint8_t * extradata
some codecs need / can use extradata like Huffman tables.
hnode huff_nodes[256][HUF_TOKENS *2]
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
An AV_PKT_DATA_PALETTE side data packet contains exactly AVPALETTE_SIZE bytes worth of palette...
static int huff_smallest_node(hnode *hnodes, int num_hnodes)
Find the lowest probability node in a Huffman table, and mark it as being assigned to a higher probab...
uint8_t * av_packet_get_side_data(const AVPacket *pkt, enum AVPacketSideDataType type, int *size)
Get side information from packet.
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
#define HUFFMAN_TABLE_SIZE
const char * name
Name of the codec implementation.
common internal API header
int width
picture width / height.
static av_cold void huff_build_tree(IdcinContext *s, int prev)
const unsigned char * buf
Libavcodec external API header.
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
main external API structure.
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
int palette_has_changed
Tell user application that palette has changed from previous frame.
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
common internal api header.
static av_cold int idcin_decode_init(AVCodecContext *avctx)
static int idcin_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
This structure stores compressed data.
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.