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idcinvideo.c File Reference


Detailed Description

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.

Definition in file idcinvideo.c.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "common.h"
#include "avcodec.h"
#include "dsputil.h"

Go to the source code of this file.

Classes

struct  hnode_t
struct  IdcinContext

Defines

#define HUF_TOKENS   256
#define HUFFMAN_TABLE_SIZE   64 * 1024
#define PALETTE_COUNT   256

Functions

static void huff_build_tree (IdcinContext *s, int prev)
static int huff_smallest_node (hnode_t *hnodes, int num_hnodes)
static int idcin_decode_end (AVCodecContext *avctx)
static int idcin_decode_frame (AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
static int idcin_decode_init (AVCodecContext *avctx)
static void idcin_decode_vlcs (IdcinContext *s)

Variables

AVCodec idcin_decoder


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