FFmpeg
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#include <stddef.h>
#include <string.h>
#include "avcodec.h"
#include "codec_internal.h"
#include "decode.h"
#include "libavutil/internal.h"
Go to the source code of this file.
Data Structures | |
struct | hnode |
struct | IdcinContext |
Macros | |
#define | HUFFMAN_TABLE_SIZE 64 * 1024 |
#define | HUF_TOKENS 256 |
#define | PALETTE_COUNT 256 |
Functions | |
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 probability. More... | |
static av_cold void | huff_build_tree (IdcinContext *s, int prev) |
static av_cold int | idcin_decode_init (AVCodecContext *avctx) |
static int | idcin_decode_vlcs (IdcinContext *s, AVFrame *frame) |
static int | idcin_decode_frame (AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *avpkt) |
Variables | |
static const FFCodecDefault | idcin_defaults [] |
const FFCodec | ff_idcin_decoder |
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 libavcodec'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.
#define HUFFMAN_TABLE_SIZE 64 * 1024 |
Definition at line 55 of file idcinvideo.c.
#define HUF_TOKENS 256 |
Definition at line 56 of file idcinvideo.c.
#define PALETTE_COUNT 256 |
Definition at line 57 of file idcinvideo.c.
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Find the lowest probability node in a Huffman table, and mark it as being assigned to a higher probability.
Definition at line 84 of file idcinvideo.c.
Referenced by huff_build_tree().
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Definition at line 116 of file idcinvideo.c.
Referenced by idcin_decode_init().
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Definition at line 146 of file idcinvideo.c.
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Definition at line 172 of file idcinvideo.c.
Referenced by idcin_decode_frame().
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Definition at line 210 of file idcinvideo.c.
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Definition at line 244 of file idcinvideo.c.
const FFCodec ff_idcin_decoder |
Definition at line 249 of file idcinvideo.c.