Data Structures | Macros | Typedefs | Functions | Variables
vqavideo.c File Reference

VQA Video Decoder. More...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "libavutil/intreadwrite.h"
#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
Include dependency graph for vqavideo.c:

Go to the source code of this file.

Data Structures

struct  VqaContext
 

Macros

#define PALETTE_COUNT   256
 
#define VQA_HEADER_SIZE   0x2A
 
#define MAX_CODEBOOK_VECTORS   0xFF00
 
#define SOLID_PIXEL_VECTORS   0x100
 
#define MAX_VECTORS   (MAX_CODEBOOK_VECTORS + SOLID_PIXEL_VECTORS)
 
#define MAX_CODEBOOK_SIZE   (MAX_VECTORS * 4 * 4)
 
#define CBF0_TAG   MKBETAG('C', 'B', 'F', '0')
 
#define CBFZ_TAG   MKBETAG('C', 'B', 'F', 'Z')
 
#define CBP0_TAG   MKBETAG('C', 'B', 'P', '0')
 
#define CBPZ_TAG   MKBETAG('C', 'B', 'P', 'Z')
 
#define CPL0_TAG   MKBETAG('C', 'P', 'L', '0')
 
#define CPLZ_TAG   MKBETAG('C', 'P', 'L', 'Z')
 
#define VPTZ_TAG   MKBETAG('V', 'P', 'T', 'Z')
 
#define CHECK_COUNT()
 
#define CHECK_COPY(idx)
 

Typedefs

typedef struct VqaContext VqaContext
 

Functions

static av_cold int vqa_decode_init (AVCodecContext *avctx)
 
static int decode_format80 (VqaContext *s, int src_size, unsigned char *dest, int dest_size, int check_size)
 
static int vqa_decode_chunk (VqaContext *s, AVFrame *frame)
 
static int vqa_decode_frame (AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
 
static av_cold int vqa_decode_end (AVCodecContext *avctx)
 

Variables

AVCodec ff_vqa_decoder
 

Detailed Description

VQA Video Decoder.

Author
Mike Melanson (melan.nosp@m.son@.nosp@m.pcisy.nosp@m.s.ne.nosp@m.t)
See also
http://wiki.multimedia.cx/index.php?title=VQA

The VQA video decoder outputs PAL8 or RGB555 colorspace data, depending on the type of data in the file.

This decoder needs the 42-byte VQHD header from the beginning of the VQA file passed through the extradata field. The VQHD header is laid out as:

bytes 0-3 chunk fourcc: 'VQHD' bytes 4-7 chunk size in big-endian format, should be 0x0000002A bytes 8-49 VQHD chunk data

Bytes 8-49 are what this decoder expects to see.

Briefly, VQA is a vector quantized animation format that operates in a VGA palettized colorspace. It operates on pixel vectors (blocks) of either 4x2 or 4x4 in size. Compressed VQA chunks can contain vector codebooks, palette information, and code maps for rendering vectors onto frames. Any of these components can also be compressed with a run-length encoding (RLE) algorithm commonly referred to as "format80".

VQA takes a novel approach to rate control. Each group of n frames (usually, n = 8) relies on a different vector codebook. Rather than transporting an entire codebook every 8th frame, the new codebook is broken up into 8 pieces and sent along with the compressed video chunks for each of the 8 frames preceding the 8 frames which require the codebook. A full codebook is also sent on the very first frame of a file. This is an interesting technique, although it makes random file seeking difficult despite the fact that the frames are all intracoded.

V1,2 VQA uses 12-bit codebook indexes. If the 12-bit indexes were packed into bytes and then RLE compressed, bytewise, the results would be poor. That is why the coding method divides each index into 2 parts, the top 4 bits and the bottom 8 bits, then RL encodes the 4-bit pieces together and the 8-bit pieces together. If most of the vectors are clustered into one group of 256 vectors, most of the 4-bit index pieces should be the same.

Definition in file vqavideo.c.

Macro Definition Documentation

#define CBF0_TAG   MKBETAG('C', 'B', 'F', '0')

Definition at line 86 of file vqavideo.c.

Referenced by vqa_decode_chunk().

#define CBFZ_TAG   MKBETAG('C', 'B', 'F', 'Z')

Definition at line 87 of file vqavideo.c.

Referenced by vqa_decode_chunk().

#define CBP0_TAG   MKBETAG('C', 'B', 'P', '0')

Definition at line 88 of file vqavideo.c.

Referenced by vqa_decode_chunk().

#define CBPZ_TAG   MKBETAG('C', 'B', 'P', 'Z')

Definition at line 89 of file vqavideo.c.

Referenced by vqa_decode_chunk().

#define CHECK_COPY (   idx)
Value:
if (idx < 0 || idx + count > dest_size) { \
av_log(s->avctx, AV_LOG_ERROR, "decode_format80 problem: next op would overflow dest_index\n"); \
av_log(s->avctx, AV_LOG_ERROR, "current src_pos = %d, count = %d, dest_size = %d\n", \
src_pos, count, dest_size); \
return AVERROR_INVALIDDATA; \
}
s
const char * s
Definition: avisynth_c.h:668
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
av_log
void av_log(void *avcl, int level, const char *fmt,...)
Definition: log.c:246
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:148
return
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame This method is called when a frame is wanted on an output For an it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return it should return
Definition: filter_design.txt:216
count
void INT64 INT64 count
Definition: avisynth_c.h:594

Definition at line 209 of file vqavideo.c.

Referenced by decode_format80().

#define CHECK_COUNT ( )
Value:
if (dest_index + count > dest_size) { \
av_log(s->avctx, AV_LOG_ERROR, "decode_format80 problem: next op would overflow dest_index\n"); \
av_log(s->avctx, AV_LOG_ERROR, "current dest_index = %d, count = %d, dest_size = %d\n", \
dest_index, count, dest_size); \
return AVERROR_INVALIDDATA; \
}
s
const char * s
Definition: avisynth_c.h:668
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
av_log
void av_log(void *avcl, int level, const char *fmt,...)
Definition: log.c:246
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:148
return
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame This method is called when a frame is wanted on an output For an it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return it should return
Definition: filter_design.txt:216
count
void INT64 INT64 count
Definition: avisynth_c.h:594

Definition at line 201 of file vqavideo.c.

Referenced by decode_format80().

#define CPL0_TAG   MKBETAG('C', 'P', 'L', '0')

Definition at line 90 of file vqavideo.c.

Referenced by vqa_decode_chunk().

#define CPLZ_TAG   MKBETAG('C', 'P', 'L', 'Z')

Definition at line 91 of file vqavideo.c.

Referenced by vqa_decode_chunk().

#define MAX_CODEBOOK_SIZE   (MAX_VECTORS * 4 * 4)

Definition at line 84 of file vqavideo.c.

Referenced by vqa_decode_chunk(), and vqa_decode_init().

#define MAX_CODEBOOK_VECTORS   0xFF00

Definition at line 81 of file vqavideo.c.

#define MAX_VECTORS   (MAX_CODEBOOK_VECTORS + SOLID_PIXEL_VECTORS)

Definition at line 83 of file vqavideo.c.

#define PALETTE_COUNT   256

Definition at line 76 of file vqavideo.c.

Referenced by vqa_decode_frame().

#define SOLID_PIXEL_VECTORS   0x100

Definition at line 82 of file vqavideo.c.

#define VPTZ_TAG   MKBETAG('V', 'P', 'T', 'Z')

Definition at line 92 of file vqavideo.c.

Referenced by vqa_decode_chunk().

#define VQA_HEADER_SIZE   0x2A

Definition at line 77 of file vqavideo.c.

Referenced by vqa_decode_init().

Typedef Documentation

typedef struct VqaContext VqaContext

Function Documentation

static int decode_format80 ( VqaContext *  s,
int  src_size,
unsigned char *  dest,
int  dest_size,
int  check_size 
)
static

Definition at line 218 of file vqavideo.c.

Referenced by vqa_decode_chunk().

static int vqa_decode_chunk ( VqaContext *  s,
AVFrame *  frame 
)
static

Definition at line 306 of file vqavideo.c.

Referenced by vqa_decode_frame().

static av_cold int vqa_decode_end ( AVCodecContext *  avctx)
static

Definition at line 618 of file vqavideo.c.

static int vqa_decode_frame ( AVCodecContext *  avctx,
void *  data,
int *  got_frame,
AVPacket *  avpkt 
)
static

Definition at line 593 of file vqavideo.c.

static av_cold int vqa_decode_init ( AVCodecContext *  avctx)
static

Definition at line 121 of file vqavideo.c.

Variable Documentation

AVCodec ff_vqa_decoder
Initial value:
= {
.name = "vqavideo",
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_WS_VQA,
.priv_data_size = sizeof(VqaContext),
.init = vqa_decode_init,
.close = vqa_decode_end,
.decode = vqa_decode_frame,
.capabilities = CODEC_CAP_DR1,
.long_name = NULL_IF_CONFIG_SMALL("Westwood Studios VQA (Vector Quantized Animation) video"),
}
init
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
CODEC_CAP_DR1
#define CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: libavcodec/avcodec.h:743
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: libavutil/internal.h:123
AV_CODEC_ID_WS_VQA
Definition: libavcodec/avcodec.h:147
close
static void close(AVCodecParserContext *s)
Definition: h264_parser.c:375
vqa_decode_end
static av_cold int vqa_decode_end(AVCodecContext *avctx)
Definition: vqavideo.c:618
vqa_decode_frame
static int vqa_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: vqavideo.c:593
VqaContext
struct VqaContext VqaContext
vqa_decode_init
static av_cold int vqa_decode_init(AVCodecContext *avctx)
Definition: vqavideo.c:121
AVMEDIA_TYPE_VIDEO
Definition: avutil.h:143
decode
static int decode(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: crystalhd.c:868

Definition at line 629 of file vqavideo.c.

Generated on Wed May 8 2024 06:52:22 for FFmpeg by   doxygen 1.8.11