mjpegdec.h

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

/*
 * MJPEG decoder
 * Copyright (c) 2000, 2001 Fabrice Bellard.
 * Copyright (c) 2003 Alex Beregszaszi
 * Copyright (c) 2003-2004 Michael Niedermayer
 *
 * 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 mjpegdec.h
 * MJPEG decoder.
 */

#ifndef MJPEGDEC_H
#define MJPEGDEC_H

#include "avcodec.h"
#include "bitstream.h"
#include "dsputil.h"
#include "mpegvideo.h"

#define MAX_COMPONENTS 4

typedef struct MJpegDecodeContext {
    AVCodecContext *avctx;
    GetBitContext gb;

    int start_code; /* current start code */
    int buffer_size;
    uint8_t *buffer;

    int16_t quant_matrixes[4][64];
    VLC vlcs[2][4];
    int qscale[4];      ///< quantizer scale calculated from quant_matrixes

    int org_height;  /* size given at codec init */
    int first_picture;    /* true if decoding first picture */
    int interlaced;     /* true if interlaced */
    int bottom_field;   /* true if bottom field */
    int lossless;
    int ls;
    int progressive;
    int rgb;
    int rct;            /* standard rct */
    int pegasus_rct;    /* pegasus reversible colorspace transform */
    int bits;           /* bits per component */

    int maxval;
    int near;         ///< near lossless bound (si 0 for lossless)
    int t1,t2,t3;
    int reset;        ///< context halfing intervall ?rename

    int width, height;
    int mb_width, mb_height;
    int nb_components;
    int component_id[MAX_COMPONENTS];
    int h_count[MAX_COMPONENTS]; /* horizontal and vertical count for each component */
    int v_count[MAX_COMPONENTS];
    int comp_index[MAX_COMPONENTS];
    int dc_index[MAX_COMPONENTS];
    int ac_index[MAX_COMPONENTS];
    int nb_blocks[MAX_COMPONENTS];
    int h_scount[MAX_COMPONENTS];
    int v_scount[MAX_COMPONENTS];
    int h_max, v_max; /* maximum h and v counts */
    int quant_index[4];   /* quant table index for each component */
    int last_dc[MAX_COMPONENTS]; /* last DEQUANTIZED dc (XXX: am I right to do that ?) */
    AVFrame picture; /* picture structure */
    int linesize[MAX_COMPONENTS];                   ///< linesize << interlaced
    int8_t *qscale_table;
    DECLARE_ALIGNED_8(DCTELEM, block[64]);
    ScanTable scantable;
    DSPContext dsp;

    int restart_interval;
    int restart_count;

    int buggy_avid;
    int cs_itu601;
    int interlace_polarity;

    int mjpb_skiptosod;

    int cur_scan; /* current scan, used by JPEG-LS */
} MJpegDecodeContext;

int ff_mjpeg_decode_init(AVCodecContext *avctx);
int ff_mjpeg_decode_end(AVCodecContext *avctx);
int ff_mjpeg_decode_frame(AVCodecContext *avctx,
                          void *data, int *data_size,
                          uint8_t *buf, int buf_size);
int ff_mjpeg_decode_dqt(MJpegDecodeContext *s);
int ff_mjpeg_decode_dht(MJpegDecodeContext *s);
int ff_mjpeg_decode_sof(MJpegDecodeContext *s);
int ff_mjpeg_decode_sos(MJpegDecodeContext *s);

#endif /* MJPEGDEC_H */