| 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 "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 | |
| 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 | static int huff_smallest_node(hnode *hnodes, int num_hnodes) { |
| 86 | int i; |
| 87 | int best, best_node; |
| 88 | |
| 89 | best = 99999999; |
| 90 | best_node = -1; |
| 91 | for(i = 0; i < num_hnodes; i++) { |
| 92 | if(hnodes[i].used) |
| 93 | continue; |
| 94 | if(!hnodes[i].count) |
| 95 | continue; |
| 96 | if(hnodes[i].count < best) { |
| 97 | best = hnodes[i].count; |
| 98 | best_node = i; |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | if(best_node == -1) |
| 103 | return -1; |
| 104 | hnodes[best_node].used = 1; |
| 105 | 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 | static av_cold void huff_build_tree(IdcinContext *s, int prev) { |
| 118 | hnode *node, *hnodes; |
| 119 | int num_hnodes, i; |
| 120 | |
| 121 | num_hnodes = HUF_TOKENS; |
| 122 | hnodes = s->huff_nodes[prev]; |
| 123 | for(i = 0; i < HUF_TOKENS * 2; i++) |
| 124 | hnodes[i].used = 0; |
| 125 | |
| 126 | while (1) { |
| 127 | node = &hnodes[num_hnodes]; /* next free node */ |
| 128 | |
| 129 | /* pick two lowest counts */ |
| 130 | node->children[0] = huff_smallest_node(hnodes, num_hnodes); |
| 131 | if(node->children[0] == -1) |
| 132 | break; /* reached the root node */ |
| 133 | |
| 134 | node->children[1] = huff_smallest_node(hnodes, num_hnodes); |
| 135 | if(node->children[1] == -1) |
| 136 | break; /* reached the root node */ |
| 137 | |
| 138 | /* combine nodes probability for new node */ |
| 139 | node->count = hnodes[node->children[0]].count + |
| 140 | hnodes[node->children[1]].count; |
| 141 | num_hnodes++; |
| 142 | } |
| 143 | |
| 144 | s->num_huff_nodes[prev] = num_hnodes - 1; |
| 145 | } |
| 146 | |
| 147 | static av_cold int idcin_decode_init(AVCodecContext *avctx) |
| 148 | { |
| 149 | IdcinContext *s = avctx->priv_data; |
| 150 | int i, j, histogram_index = 0; |
| 151 | unsigned char *histograms; |
| 152 | |
| 153 | s->avctx = avctx; |
| 154 | avctx->pix_fmt = AV_PIX_FMT_PAL8; |
| 155 | |
| 156 | /* make sure the Huffman tables make it */ |
| 157 | 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 | histograms = (unsigned char *)s->avctx->extradata; |
| 164 | for (i = 0; i < 256; i++) { |
| 165 | for(j = 0; j < HUF_TOKENS; j++) |
| 166 | s->huff_nodes[i][j].count = histograms[histogram_index++]; |
| 167 | huff_build_tree(s, i); |
| 168 | } |
| 169 | |
| 170 | return 0; |
| 171 | } |
| 172 | |
| 173 | static int idcin_decode_vlcs(IdcinContext *s, AVFrame *frame) |
| 174 | { |
| 175 | hnode *hnodes; |
| 176 | long x, y; |
| 177 | int prev; |
| 178 | unsigned char v = 0; |
| 179 | int bit_pos, node_num, dat_pos; |
| 180 | |
| 181 | prev = bit_pos = dat_pos = 0; |
| 182 | for (y = 0; y < (frame->linesize[0] * s->avctx->height); |
| 183 | y += frame->linesize[0]) { |
| 184 | for (x = y; x < y + s->avctx->width; x++) { |
| 185 | node_num = s->num_huff_nodes[prev]; |
| 186 | hnodes = s->huff_nodes[prev]; |
| 187 | |
| 188 | while(node_num >= HUF_TOKENS) { |
| 189 | if(!bit_pos) { |
| 190 | if(dat_pos >= s->size) { |
| 191 | av_log(s->avctx, AV_LOG_ERROR, "Huffman decode error.\n"); |
| 192 | return -1; |
| 193 | } |
| 194 | bit_pos = 8; |
| 195 | v = s->buf[dat_pos++]; |
| 196 | } |
| 197 | |
| 198 | node_num = hnodes[node_num].children[v & 0x01]; |
| 199 | v = v >> 1; |
| 200 | bit_pos--; |
| 201 | } |
| 202 | |
| 203 | frame->data[0][x] = node_num; |
| 204 | prev = node_num; |
| 205 | } |
| 206 | } |
| 207 | |
| 208 | return 0; |
| 209 | } |
| 210 | |
| 211 | static int idcin_decode_frame(AVCodecContext *avctx, |
| 212 | void *data, int *got_frame, |
| 213 | AVPacket *avpkt) |
| 214 | { |
| 215 | const uint8_t *buf = avpkt->data; |
| 216 | int buf_size = avpkt->size; |
| 217 | IdcinContext *s = avctx->priv_data; |
| 218 | const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, NULL); |
| 219 | AVFrame *frame = data; |
| 220 | int ret; |
| 221 | |
| 222 | s->buf = buf; |
| 223 | s->size = buf_size; |
| 224 | |
| 225 | if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) |
| 226 | return ret; |
| 227 | |
| 228 | if (idcin_decode_vlcs(s, frame)) |
| 229 | return AVERROR_INVALIDDATA; |
| 230 | |
| 231 | if (pal) { |
| 232 | frame->palette_has_changed = 1; |
| 233 | memcpy(s->pal, pal, AVPALETTE_SIZE); |
| 234 | } |
| 235 | /* make the palette available on the way out */ |
| 236 | memcpy(frame->data[1], s->pal, AVPALETTE_SIZE); |
| 237 | |
| 238 | *got_frame = 1; |
| 239 | |
| 240 | /* report that the buffer was completely consumed */ |
| 241 | return buf_size; |
| 242 | } |
| 243 | |
| 244 | AVCodec ff_idcin_decoder = { |
| 245 | .name = "idcinvideo", |
| 246 | .long_name = NULL_IF_CONFIG_SMALL("id Quake II CIN video"), |
| 247 | .type = AVMEDIA_TYPE_VIDEO, |
| 248 | .id = AV_CODEC_ID_IDCIN, |
| 249 | .priv_data_size = sizeof(IdcinContext), |
| 250 | .init = idcin_decode_init, |
| 251 | .decode = idcin_decode_frame, |
| 252 | .capabilities = CODEC_CAP_DR1, |
| 253 | }; |