| /* |
| * id Quake II CIN Video Decoder |
| * Copyright (C) 2003 the ffmpeg project |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| /** |
| * @file libavcodec/idcinvideo.c |
| * id Quake II Cin Video Decoder by Dr. Tim Ferguson |
| * For more information about the id CIN format, visit: |
| * http://www.csse.monash.edu.au/~timf/ |
| * |
| * This video decoder outputs PAL8 colorspace data. Interacting with this |
| * decoder is a little involved. During initialization, the demuxer must |
| * transmit the 65536-byte Huffman table(s) to the decoder via extradata. |
| * Then, whenever a palette change is encountered while demuxing the file, |
| * the demuxer must use the same extradata space to transmit an |
| * AVPaletteControl structure. |
| * |
| * id CIN video is purely Huffman-coded, intraframe-only codec. It achieves |
| * a little more compression by exploiting the fact that adjacent pixels |
| * tend to be similar. |
| * |
| * Note that this decoder could use ffmpeg's optimized VLC facilities |
| * rather than naive, tree-based Huffman decoding. However, there are 256 |
| * Huffman tables. Plus, the VLC bit coding order is right -> left instead |
| * or left -> right, so all of the bits would have to be reversed. Further, |
| * the original Quake II implementation likely used a similar naive |
| * decoding algorithm and it worked fine on much lower spec machines. |
| */ |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <unistd.h> |
| |
| #include "avcodec.h" |
| |
| #define HUFFMAN_TABLE_SIZE 64 * 1024 |
| #define HUF_TOKENS 256 |
| #define PALETTE_COUNT 256 |
| |
| typedef struct |
| { |
| int count; |
| unsigned char used; |
| int children[2]; |
| } hnode; |
| |
| typedef struct IdcinContext { |
| |
| AVCodecContext *avctx; |
| AVFrame frame; |
| |
| const unsigned char *buf; |
| int size; |
| |
| hnode huff_nodes[256][HUF_TOKENS*2]; |
| int num_huff_nodes[256]; |
| |
| } IdcinContext; |
| |
| /* |
| * Find the lowest probability node in a Huffman table, and mark it as |
| * being assigned to a higher probability. |
| * Returns the node index of the lowest unused node, or -1 if all nodes |
| * are used. |
| */ |
| static int huff_smallest_node(hnode *hnodes, int num_hnodes) { |
| int i; |
| int best, best_node; |
| |
| best = 99999999; |
| best_node = -1; |
| for(i = 0; i < num_hnodes; i++) { |
| if(hnodes[i].used) |
| continue; |
| if(!hnodes[i].count) |
| continue; |
| if(hnodes[i].count < best) { |
| best = hnodes[i].count; |
| best_node = i; |
| } |
| } |
| |
| if(best_node == -1) |
| return -1; |
| hnodes[best_node].used = 1; |
| return best_node; |
| } |
| |
| /* |
| * Build the Huffman tree using the generated/loaded probabilities histogram. |
| * |
| * On completion: |
| * huff_nodes[prev][i < HUF_TOKENS] - are the nodes at the base of the tree. |
| * huff_nodes[prev][i >= HUF_TOKENS] - are used to construct the tree. |
| * num_huff_nodes[prev] - contains the index to the root node of the tree. |
| * That is: huff_nodes[prev][num_huff_nodes[prev]] is the root node. |
| */ |
| static av_cold void huff_build_tree(IdcinContext *s, int prev) { |
| hnode *node, *hnodes; |
| int num_hnodes, i; |
| |
| num_hnodes = HUF_TOKENS; |
| hnodes = s->huff_nodes[prev]; |
| for(i = 0; i < HUF_TOKENS * 2; i++) |
| hnodes[i].used = 0; |
| |
| while (1) { |
| node = &hnodes[num_hnodes]; /* next free node */ |
| |
| /* pick two lowest counts */ |
| node->children[0] = huff_smallest_node(hnodes, num_hnodes); |
| if(node->children[0] == -1) |
| break; /* reached the root node */ |
| |
| node->children[1] = huff_smallest_node(hnodes, num_hnodes); |
| if(node->children[1] == -1) |
| break; /* reached the root node */ |
| |
| /* combine nodes probability for new node */ |
| node->count = hnodes[node->children[0]].count + |
| hnodes[node->children[1]].count; |
| num_hnodes++; |
| } |
| |
| s->num_huff_nodes[prev] = num_hnodes - 1; |
| } |
| |
| static av_cold int idcin_decode_init(AVCodecContext *avctx) |
| { |
| IdcinContext *s = avctx->priv_data; |
| int i, j, histogram_index = 0; |
| unsigned char *histograms; |
| |
| s->avctx = avctx; |
| avctx->pix_fmt = PIX_FMT_PAL8; |
| |
| /* make sure the Huffman tables make it */ |
| if (s->avctx->extradata_size != HUFFMAN_TABLE_SIZE) { |
| av_log(s->avctx, AV_LOG_ERROR, " id CIN video: expected extradata size of %d\n", HUFFMAN_TABLE_SIZE); |
| return -1; |
| } |
| |
| /* build the 256 Huffman decode trees */ |
| histograms = (unsigned char *)s->avctx->extradata; |
| for (i = 0; i < 256; i++) { |
| for(j = 0; j < HUF_TOKENS; j++) |
| s->huff_nodes[i][j].count = histograms[histogram_index++]; |
| huff_build_tree(s, i); |
| } |
| |
| s->frame.data[0] = NULL; |
| |
| return 0; |
| } |
| |
| static void idcin_decode_vlcs(IdcinContext *s) |
| { |
| hnode *hnodes; |
| long x, y; |
| int prev; |
| unsigned char v = 0; |
| int bit_pos, node_num, dat_pos; |
| |
| prev = bit_pos = dat_pos = 0; |
| for (y = 0; y < (s->frame.linesize[0] * s->avctx->height); |
| y += s->frame.linesize[0]) { |
| for (x = y; x < y + s->avctx->width; x++) { |
| node_num = s->num_huff_nodes[prev]; |
| hnodes = s->huff_nodes[prev]; |
| |
| while(node_num >= HUF_TOKENS) { |
| if(!bit_pos) { |
| if(dat_pos >= s->size) { |
| av_log(s->avctx, AV_LOG_ERROR, "Huffman decode error.\n"); |
| return; |
| } |
| bit_pos = 8; |
| v = s->buf[dat_pos++]; |
| } |
| |
| node_num = hnodes[node_num].children[v & 0x01]; |
| v = v >> 1; |
| bit_pos--; |
| } |
| |
| s->frame.data[0][x] = node_num; |
| prev = node_num; |
| } |
| } |
| } |
| |
| static int idcin_decode_frame(AVCodecContext *avctx, |
| void *data, int *data_size, |
| const uint8_t *buf, int buf_size) |
| { |
| IdcinContext *s = avctx->priv_data; |
| AVPaletteControl *palette_control = avctx->palctrl; |
| |
| s->buf = buf; |
| s->size = buf_size; |
| |
| if (s->frame.data[0]) |
| avctx->release_buffer(avctx, &s->frame); |
| |
| if (avctx->get_buffer(avctx, &s->frame)) { |
| av_log(avctx, AV_LOG_ERROR, " id CIN Video: get_buffer() failed\n"); |
| return -1; |
| } |
| |
| idcin_decode_vlcs(s); |
| |
| /* make the palette available on the way out */ |
| memcpy(s->frame.data[1], palette_control->palette, PALETTE_COUNT * 4); |
| /* If palette changed inform application*/ |
| if (palette_control->palette_changed) { |
| palette_control->palette_changed = 0; |
| s->frame.palette_has_changed = 1; |
| } |
| |
| *data_size = sizeof(AVFrame); |
| *(AVFrame*)data = s->frame; |
| |
| /* report that the buffer was completely consumed */ |
| return buf_size; |
| } |
| |
| static av_cold int idcin_decode_end(AVCodecContext *avctx) |
| { |
| IdcinContext *s = avctx->priv_data; |
| |
| if (s->frame.data[0]) |
| avctx->release_buffer(avctx, &s->frame); |
| |
| return 0; |
| } |
| |
| AVCodec idcin_decoder = { |
| "idcinvideo", |
| CODEC_TYPE_VIDEO, |
| CODEC_ID_IDCIN, |
| sizeof(IdcinContext), |
| idcin_decode_init, |
| NULL, |
| idcin_decode_end, |
| idcin_decode_frame, |
| CODEC_CAP_DR1, |
| .long_name = NULL_IF_CONFIG_SMALL("id Quake II CIN video"), |
| }; |
| |