quicktime/ffmpeg/libavcodec/idcinvideo.c

   1 /*
   2  * Id Quake II CIN Video Decoder
   3  * Copyright (C) 2003 the ffmpeg project
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  *
  19  */
  20
  21 /**
  22  * @file idcinvideo.c
  23  * Id Quake II Cin Video Decoder by Dr. Tim Ferguson
  24  * For more information about the Id CIN format, visit:
  25  *   http://www.csse.monash.edu.au/~timf/
  26  *
  27  * This video decoder outputs PAL8 colorspace data. Interacting with this
  28  * decoder is a little involved. During initialization, the demuxer must
  29  * transmit the 65536-byte Huffman table(s) to the decoder via extradata.
  30  * Then, whenever a palette change is encountered while demuxing the file,
  31  * the demuxer must use the same extradata space to transmit an
  32  * AVPaletteControl structure.
  33  *
  34  * Id CIN video is purely Huffman-coded, intraframe-only codec. It achieves
  35  * a little more compression by exploiting the fact that adjacent pixels
  36  * tend to be similar.
  37  *
  38  * Note that this decoder could use ffmpeg's optimized VLC facilities
  39  * rather than naive, tree-based Huffman decoding. However, there are 256
  40  * Huffman tables. Plus, the VLC bit coding order is right -> left instead
  41  * or left -> right, so all of the bits would have to be reversed. Further,
  42  * the original Quake II implementation likely used a similar naive
  43  * decoding algorithm and it worked fine on much lower spec machines.
  44  */
  45
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50
  51 #include "common.h"
  52 #include "avcodec.h"
  53 #include "dsputil.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_t;
  65
  66 typedef struct IdcinContext {
  67
  68     AVCodecContext *avctx;
  69     DSPContext dsp;
  70     AVFrame frame;
  71
  72     unsigned char *buf;
  73     int size;
  74
  75     hnode_t huff_nodes[256][HUF_TOKENS*2];
  76     int num_huff_nodes[256];
  77
  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  * Returns the node index of the lowest unused node, or -1 if all nodes
  84  * are used.
  85  */
  86 static int huff_smallest_node(hnode_t *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 void huff_build_tree(IdcinContext *s, int prev) {
 119     hnode_t *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 int idcin_decode_init(AVCodecContext *avctx)
 149 {
 150     IdcinContext *s = (IdcinContext *)avctx->priv_data;
 151     int i, j, histogram_index = 0;
 152     unsigned char *histograms;
 153
 154     s->avctx = avctx;
 155     avctx->pix_fmt = PIX_FMT_PAL8;
 156     avctx->has_b_frames = 0;
 157     dsputil_init(&s->dsp, avctx);
 158
 159     /* make sure the Huffman tables make it */
 160     if (s->avctx->extradata_size != HUFFMAN_TABLE_SIZE) {
 161         av_log(s->avctx, AV_LOG_ERROR, "  Id CIN video: expected extradata size of %d\n", HUFFMAN_TABLE_SIZE);
 162         return -1;
 163     }
 164
 165     /* build the 256 Huffman decode trees */
 166     histograms = (unsigned char *)s->avctx->extradata;
 167     for (i = 0; i < 256; i++) {
 168         for(j = 0; j < HUF_TOKENS; j++)
 169             s->huff_nodes[i][j].count = histograms[histogram_index++];
 170         huff_build_tree(s, i);
 171     }
 172
 173     s->frame.data[0] = NULL;
 174
 175     return 0;
 176 }
 177
 178 static void idcin_decode_vlcs(IdcinContext *s)
 179 {
 180     hnode_t *hnodes;
 181     long x, y;
 182     int prev;
 183     unsigned char v = 0;
 184     int bit_pos, node_num, dat_pos;
 185
 186     prev = bit_pos = dat_pos = 0;
 187     for (y = 0; y < (s->frame.linesize[0] * s->avctx->height);
 188         y += s->frame.linesize[0]) {
 189         for (x = y; x < y + s->avctx->width; x++) {
 190             node_num = s->num_huff_nodes[prev];
 191             hnodes = s->huff_nodes[prev];
 192
 193             while(node_num >= HUF_TOKENS) {
 194                 if(!bit_pos) {
 195                     if(dat_pos >= s->size) {
 196                         av_log(s->avctx, AV_LOG_ERROR, "Huffman decode error.\n");
 197                         return;
 198                     }
 199                     bit_pos = 8;
 200                     v = s->buf[dat_pos++];
 201                 }
 202
 203                 node_num = hnodes[node_num].children[v & 0x01];
 204                 v = v >> 1;
 205                 bit_pos--;
 206             }
 207
 208             s->frame.data[0][x] = node_num;
 209             prev = node_num;
 210         }
 211     }
 212 }
 213
 214 static int idcin_decode_frame(AVCodecContext *avctx,
 215                               void *data, int *data_size,
 216                               uint8_t *buf, int buf_size)
 217 {
 218     IdcinContext *s = (IdcinContext *)avctx->priv_data;
 219     AVPaletteControl *palette_control = avctx->palctrl;
 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 (avctx->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     /* make the palette available on the way out */
 235     memcpy(s->frame.data[1], palette_control->palette, PALETTE_COUNT * 4);
 236     /* If palette changed inform application*/
 237     if (palette_control->palette_changed) {
 238         palette_control->palette_changed = 0;
 239         s->frame.palette_has_changed = 1;
 240     }
 241
 242     *data_size = sizeof(AVFrame);
 243     *(AVFrame*)data = s->frame;
 244
 245     /* report that the buffer was completely consumed */
 246     return buf_size;
 247 }
 248
 249 static int idcin_decode_end(AVCodecContext *avctx)
 250 {
 251     IdcinContext *s = (IdcinContext *)avctx->priv_data;
 252
 253     if (s->frame.data[0])
 254         avctx->release_buffer(avctx, &s->frame);
 255
 256     return 0;
 257 }
 258
 259 AVCodec idcin_decoder = {
 260     "idcinvideo",
 261     CODEC_TYPE_VIDEO,
 262     CODEC_ID_IDCIN,
 263     sizeof(IdcinContext),
 264     idcin_decode_init,
 265     NULL,
 266     idcin_decode_end,
 267     idcin_decode_frame,
 268     CODEC_CAP_DR1,
 269 };
 270