cinepak.c

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

/*
 * Cinepak 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 cinepak.c
 * Cinepak video decoder
 * by Ewald Snel <[e-mail]>
 * For more information on the Cinepak algorithm, visit:
 *   http://www.csse.monash.edu.au/~timf/
 * For more information on the quirky data inside Sega FILM/CPK files, visit:
 *   http://wiki.multimedia.cx/index.php?title=Sega_FILM
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "avcodec.h"
#include "dsputil.h"


typedef struct {
    uint8_t  y0, y1, y2, y3;
    uint8_t  u, v;
} cvid_codebook_t;

#define MAX_STRIPS      32

typedef struct {
    uint16_t          id;
    uint16_t          x1, y1;
    uint16_t          x2, y2;
    cvid_codebook_t   v4_codebook[256];
    cvid_codebook_t   v1_codebook[256];
} cvid_strip_t;

typedef struct CinepakContext {

    AVCodecContext *avctx;
    DSPContext dsp;
    AVFrame frame;

    unsigned char *data;
    int size;

    int width, height;

    int palette_video;
    cvid_strip_t strips[MAX_STRIPS];

    int sega_film_skip_bytes;

} CinepakContext;

static void cinepak_decode_codebook (cvid_codebook_t *codebook,
                                     int chunk_id, int size, uint8_t *data)
{
    uint8_t *eod = (data + size);
    uint32_t flag, mask;
    int      i, n;

    /* check if this chunk contains 4- or 6-element vectors */
    n    = (chunk_id & 0x0400) ? 4 : 6;
    flag = 0;
    mask = 0;

    for (i=0; i < 256; i++) {
        if ((chunk_id & 0x0100) && !(mask >>= 1)) {
            if ((data + 4) > eod)
                break;

            flag  = AV_RB32 (data);
            data += 4;
            mask  = 0x80000000;
        }

        if (!(chunk_id & 0x0100) || (flag & mask)) {
            if ((data + n) > eod)
                break;

            if (n == 6) {
                codebook[i].y0 = *data++;
                codebook[i].y1 = *data++;
                codebook[i].y2 = *data++;
                codebook[i].y3 = *data++;
                codebook[i].u  = 128 + *data++;
                codebook[i].v  = 128 + *data++;
            } else {
                /* this codebook type indicates either greyscale or
                 * palettized video; if palettized, U & V components will
                 * not be used so it is safe to set them to 128 for the
                 * benefit of greyscale rendering in YUV420P */
                codebook[i].y0 = *data++;
                codebook[i].y1 = *data++;
                codebook[i].y2 = *data++;
                codebook[i].y3 = *data++;
                codebook[i].u  = 128;
                codebook[i].v  = 128;
            }
        }
    }
}

static int cinepak_decode_vectors (CinepakContext *s, cvid_strip_t *strip,
                                   int chunk_id, int size, uint8_t *data)
{
    uint8_t         *eod = (data + size);
    uint32_t         flag, mask;
    cvid_codebook_t *codebook;
    unsigned int     x, y;
    uint32_t         iy[4];
    uint32_t         iu[2];
    uint32_t         iv[2];

    flag = 0;
    mask = 0;

    for (y=strip->y1; y < strip->y2; y+=4) {

        iy[0] = strip->x1 + (y * s->frame.linesize[0]);
        iy[1] = iy[0] + s->frame.linesize[0];
        iy[2] = iy[1] + s->frame.linesize[0];
        iy[3] = iy[2] + s->frame.linesize[0];
        iu[0] = (strip->x1/2) + ((y/2) * s->frame.linesize[1]);
        iu[1] = iu[0] + s->frame.linesize[1];
        iv[0] = (strip->x1/2) + ((y/2) * s->frame.linesize[2]);
        iv[1] = iv[0] + s->frame.linesize[2];

        for (x=strip->x1; x < strip->x2; x+=4) {
            if ((chunk_id & 0x0100) && !(mask >>= 1)) {
                if ((data + 4) > eod)
                    return -1;

                flag  = AV_RB32 (data);
                data += 4;
                mask  = 0x80000000;
            }

            if (!(chunk_id & 0x0100) || (flag & mask)) {
                if (!(chunk_id & 0x0200) && !(mask >>= 1)) {
                    if ((data + 4) > eod)
                        return -1;

                    flag  = AV_RB32 (data);
                    data += 4;
                    mask  = 0x80000000;
                }

                if ((chunk_id & 0x0200) || (~flag & mask)) {
                    if (data >= eod)
                        return -1;

                    codebook = &strip->v1_codebook[*data++];
                    s->frame.data[0][iy[0] + 0] = codebook->y0;
                    s->frame.data[0][iy[0] + 1] = codebook->y0;
                    s->frame.data[0][iy[1] + 0] = codebook->y0;
                    s->frame.data[0][iy[1] + 1] = codebook->y0;
                    if (!s->palette_video) {
                        s->frame.data[1][iu[0]] = codebook->u;
                        s->frame.data[2][iv[0]] = codebook->v;
                    }

                    s->frame.data[0][iy[0] + 2] = codebook->y1;
                    s->frame.data[0][iy[0] + 3] = codebook->y1;
                    s->frame.data[0][iy[1] + 2] = codebook->y1;
                    s->frame.data[0][iy[1] + 3] = codebook->y1;
                    if (!s->palette_video) {
                        s->frame.data[1][iu[0] + 1] = codebook->u;
                        s->frame.data[2][iv[0] + 1] = codebook->v;
                    }

                    s->frame.data[0][iy[2] + 0] = codebook->y2;
                    s->frame.data[0][iy[2] + 1] = codebook->y2;
                    s->frame.data[0][iy[3] + 0] = codebook->y2;
                    s->frame.data[0][iy[3] + 1] = codebook->y2;
                    if (!s->palette_video) {
                        s->frame.data[1][iu[1]] = codebook->u;
                        s->frame.data[2][iv[1]] = codebook->v;
                    }

                    s->frame.data[0][iy[2] + 2] = codebook->y3;
                    s->frame.data[0][iy[2] + 3] = codebook->y3;
                    s->frame.data[0][iy[3] + 2] = codebook->y3;
                    s->frame.data[0][iy[3] + 3] = codebook->y3;
                    if (!s->palette_video) {
                        s->frame.data[1][iu[1] + 1] = codebook->u;
                        s->frame.data[2][iv[1] + 1] = codebook->v;
                    }

                } else if (flag & mask) {
                    if ((data + 4) > eod)
                        return -1;

                    codebook = &strip->v4_codebook[*data++];
                    s->frame.data[0][iy[0] + 0] = codebook->y0;
                    s->frame.data[0][iy[0] + 1] = codebook->y1;
                    s->frame.data[0][iy[1] + 0] = codebook->y2;
                    s->frame.data[0][iy[1] + 1] = codebook->y3;
                    if (!s->palette_video) {
                        s->frame.data[1][iu[0]] = codebook->u;
                        s->frame.data[2][iv[0]] = codebook->v;
                    }

                    codebook = &strip->v4_codebook[*data++];
                    s->frame.data[0][iy[0] + 2] = codebook->y0;
                    s->frame.data[0][iy[0] + 3] = codebook->y1;
                    s->frame.data[0][iy[1] + 2] = codebook->y2;
                    s->frame.data[0][iy[1] + 3] = codebook->y3;
                    if (!s->palette_video) {
                        s->frame.data[1][iu[0] + 1] = codebook->u;
                        s->frame.data[2][iv[0] + 1] = codebook->v;
                    }

                    codebook = &strip->v4_codebook[*data++];
                    s->frame.data[0][iy[2] + 0] = codebook->y0;
                    s->frame.data[0][iy[2] + 1] = codebook->y1;
                    s->frame.data[0][iy[3] + 0] = codebook->y2;