lcldec.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

/*
 * LCL (LossLess Codec Library) Codec
 * Copyright (c) 2002-2004 Roberto Togni
 *
 * 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 lcl.c
 * LCL (LossLess Codec Library) Video Codec
 * Decoder for MSZH and ZLIB codecs
 * Experimental encoder for ZLIB RGB24
 *
 * Fourcc: MSZH, ZLIB
 *
 * Original Win32 dll:
 * Ver2.23 By Kenji Oshima 2000.09.20
 * avimszh.dll, avizlib.dll
 *
 * A description of the decoding algorithm can be found here:
 *   http://www.pcisys.net/~melanson/codecs
 *
 * Supports: BGR24 (RGB 24bpp)
 *
 */

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

#include "avcodec.h"
#include "bitstream.h"
#include "lcl.h"

#ifdef CONFIG_ZLIB
#include <zlib.h>
#endif

/*
 * Decoder context
 */
typedef struct LclDecContext {
    AVFrame pic;

    // Image type
    int imgtype;
    // Compression type
    int compression;
    // Flags
    int flags;
    // Decompressed data size
    unsigned int decomp_size;
    // Decompression buffer
    unsigned char* decomp_buf;
#ifdef CONFIG_ZLIB
    z_stream zstream;
#endif
} LclDecContext;


/*
 *
 * Helper functions
 *
 */
static inline unsigned char fix (int pix14)
{
    int tmp;

    tmp = (pix14 + 0x80000) >> 20;
    if (tmp < 0)
        return 0;
    if (tmp > 255)
        return 255;
    return tmp;
}



static inline unsigned char get_b (unsigned char yq, signed char bq)
{
    return fix((yq << 20) + bq * 1858076);
}



static inline unsigned char get_g (unsigned char yq, signed char bq, signed char rq)
{
    return fix((yq << 20) - bq * 360857 - rq * 748830);
}



static inline unsigned char get_r (unsigned char yq, signed char rq)
{
    return fix((yq << 20) + rq * 1470103);
}



static unsigned int mszh_decomp(unsigned char * srcptr, int srclen, unsigned char * destptr, unsigned int destsize)
{
    unsigned char *destptr_bak = destptr;
    unsigned char *destptr_end = destptr + destsize;
    unsigned char mask = 0;
    unsigned char maskbit = 0;
    unsigned int ofs, cnt;

    while ((srclen > 0) && (destptr < destptr_end)) {
        if (maskbit == 0) {
            mask = *(srcptr++);
            maskbit = 8;
            srclen--;
            continue;
        }
        if ((mask & (1 << (--maskbit))) == 0) {
            if (destptr + 4 > destptr_end)
                break;
            *(int*)destptr = *(int*)srcptr;
            srclen -= 4;
            destptr += 4;
            srcptr += 4;
        } else {
            ofs = *(srcptr++);
            cnt = *(srcptr++);
            ofs += cnt * 256;;
            cnt = ((cnt >> 3) & 0x1f) + 1;
            ofs &= 0x7ff;
            srclen -= 2;
            cnt *= 4;
            if (destptr + cnt > destptr_end) {
                cnt =  destptr_end - destptr;
            }
            for (; cnt > 0; cnt--) {
                *(destptr) = *(destptr - ofs);
                destptr++;
            }
        }
    }

    return (destptr - destptr_bak);
}



/*
 *
 * Decode a frame
 *
 */
static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
{
    LclDecContext * const c = avctx->priv_data;
    unsigned char *encoded = (unsigned char *)buf;
    unsigned int pixel_ptr;
    int row, col;
    unsigned char *outptr;
    unsigned int width = avctx->width; // Real image width
    unsigned int height = avctx->height; // Real image height
    unsigned int mszh_dlen;
    unsigned char yq, y1q, uq, vq;
    int uqvq;
    unsigned int mthread_inlen, mthread_outlen;
#ifdef CONFIG_ZLIB
    int zret; // Zlib return code
#endif
    unsigned int len = buf_size;

    if(c->pic.data[0])
        avctx->release_buffer(avctx, &c->pic);

    c->pic.reference = 0;
    c->pic.buffer_hints = FF_BUFFER_HINTS_VALID;
    if(avctx->get_buffer(avctx, &c->pic) < 0){
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return -1;
    }

    outptr = c->pic.data[0]; // Output image pointer

    /* Decompress frame */
    switch (avctx->codec_id) {
    case CODEC_ID_MSZH:
        switch (c->compression) {
        case COMP_MSZH:
            if (c->flags & FLAG_MULTITHREAD) {
                mthread_inlen = *((unsigned int*)encoded);
                mthread_outlen = *((unsigned int*)(encoded+4));
                if (mthread_outlen > c->decomp_size) // this should not happen
                    mthread_outlen = c->decomp_size;
                mszh_dlen = mszh_decomp(encoded + 8, mthread_inlen, c->decomp_buf, c->decomp_size);
                if (mthread_outlen != mszh_dlen) {
                    av_log(avctx, AV_LOG_ERROR, "Mthread1 decoded size differs (%d != %d)\n",
                           mthread_outlen, mszh_dlen);
                    return -1;
                }
                mszh_dlen = mszh_decomp(encoded + 8 + mthread_inlen, len - mthread_inlen,
                                        c->decomp_buf + mthread_outlen, c->decomp_size - mthread_outlen);
                if (mthread_outlen != mszh_dlen) {
                    av_log(avctx, AV_LOG_ERROR, "Mthread2 decoded size differs (%d != %d)\n",
                           mthread_outlen, mszh_dlen);
                    return -1;
                }
                encoded = c->decomp_buf;
                len = c->decomp_size;
            } else {
                mszh_dlen = mszh_decomp(encoded, len, c->decomp_buf, c->decomp_size);
                if (c->decomp_size != mszh_dlen) {
                    av_log(avctx, AV_LOG_ERROR, "Decoded size differs (%d != %d)\n",
                           c->decomp_size, mszh_dlen);
                    return -1;
                }
                encoded = c->decomp_buf;
                len = mszh_dlen;
            }
            break;
        case COMP_MSZH_NOCOMP:
            break;
        default:
            av_log(avctx, AV_LOG_ERROR, "BUG! Unknown MSZH compression in frame decoder.\n");
            return -1;
        }
        break;
    case CODEC_ID_ZLIB:
#ifdef CONFIG_ZLIB
        /* Using the original dll with normal compression (-1) and RGB format
         * gives a file with ZLIB fourcc, but frame is really uncompressed.
         * To be sure that's true check also frame size */
        if ((c->compression == COMP_ZLIB_NORMAL) && (c->imgtype == IMGTYPE_RGB24) &&
            (len == width * height * 3))
            break;
        zret = inflateReset(&(c->zstream));
        if (zret != Z_OK) {
            av_log(avctx, AV_LOG_ERROR, "Inflate reset error: %d\n", zret);
            return -1;
        }
        if (c->flags & FLAG_MULTITHREAD) {
            mthread_inlen = *((unsigned int*)encoded);
            mthread_outlen = *((unsigned int*)(encoded+4));
            if (mthread_outlen > c->decomp_size)
                mthread_outlen = c->decomp_size;
            c->zstream.next_in = encoded + 8;
            c->zstream.avail_in = mthread_inlen;
            c->zstream.next_out = c->decomp_buf;
            c->zstream.avail_out = c->decomp_size;
            zret = inflate(&(c->zstream), Z_FINISH);
            if ((zret != Z_OK) && (zret != Z_STREAM_END)) {
                av_log(avctx, AV_LOG_ERROR, "Mthread1 inflate error: %d\n", zret);
                return -1;
            }
            if (mthread_outlen != (unsigned int)(c->zstream.total_out)) {
                av_log(avctx, AV_LOG_ERROR, "Mthread1 decoded size differs (%u != %lu)\n",
                       mthread_outlen, c->zstream.total_out);
                return -1;
            }
            zret = inflateReset(&(c->zstream));
            if (zret != Z_OK) {
                av_log(avctx, AV_LOG_ERROR, "Mthread2 inflate reset error: %d\n", zret);
                return -1;
            }
            c->zstream.next_in = encoded + 8 + mthread_inlen;
            c->zstream.avail_in = len - mthread_inlen;
            c->zstream.next_out = c->decomp_buf + mthread_outlen;
            c->zstream.avail_out = c->decomp_size - mthread_outlen;
            zret = inflate(&(c->zstream), Z_FINISH);
            if ((zret != Z_OK) && (zret != Z_STREAM_END)) {
                av_log(avctx, AV_LOG_ERROR, "Mthread2 inflate error: %d\n", zret);
                return -1;
            }
            if (mthread_outlen != (unsigned int)(c->zstream.total_out)) {
                av_log(avctx, AV_LOG_ERROR, "Mthread2 decoded size differs (%d != %lu)\n",
                       mthread_outlen, c->zstream.total_out);
                return -1;
            }
        } else {
            c->zstream.next_in = encoded;
            c->zstream.avail_in = len;
            c->zstream.next_out = c->decomp_buf;
            c->zstream.avail_out = c->decomp_size;
            zret = inflate(&(c->zstream), Z_FINISH);
            if ((zret != Z_OK) && (zret != Z_STREAM_END)) {
                av_log(avctx, AV_LOG_ERROR, "Inflate error: %d\n", zret);
                return -1;
            }
            if (c->decomp_size != (unsigned int)(c->zstream.total_out)) {
                av_log(avctx, AV_LOG_ERROR, "Decoded size differs (%d != %lu)\n",
                       c->decomp_size, c->zstream.total_out);
                return -1;
            }
        }
        encoded = c->decomp_buf;
        len = c->decomp_size;;
#else
        av_log(avctx, AV_LOG_ERROR, "BUG! Zlib support not compiled in frame decoder.\n");
        return -1;
#endif
        break;
    default:
        av_log(avctx, AV_LOG_ERROR, "BUG! Unknown codec in frame decoder compression switch.\n");
        return -1;
    }


    /* Apply PNG filter */
    if ((avctx->codec_id == CODEC_ID_ZLIB) && (c->flags & FLAG_PNGFILTER)) {
        switch (c->imgtype) {
        case IMGTYPE_YUV111:
        case IMGTYPE_RGB24:
            for (row = 0; row < height; row++) {
                pixel_ptr = row * width * 3;
                yq = encoded[pixel_ptr++];
                uqvq = AV_RL16(encoded+pixel_ptr);
                pixel_ptr += 2;
                for (col = 1; col < width; col++) {
                    encoded[pixel_ptr] = yq -= encoded[pixel_ptr];
                    uqvq -= AV_RL16(encoded+pixel_ptr+1);
                    AV_WL16(encoded+pixel_ptr+1, uqvq);
                    pixel_ptr += 3;
                }
            }
            break;
        case IMGTYPE_YUV422:
            for (row = 0; row < height; row++) {
                pixel_ptr = row * width * 2;
                yq = uq = vq =0;
                for (col = 0; col < width/4; col++) {
                    encoded[pixel_ptr] = yq -= encoded[pixel_ptr];
                    encoded[pixel_ptr+1] = yq -= encoded[pixel_ptr+1];
                    encoded[pixel_ptr+2] = yq -= encoded[pixel_ptr+2];
                    encoded[pixel_ptr+3] = yq -= encoded[pixel_ptr+3];
                    encoded[pixel_ptr+4] = uq -= encoded[pixel_ptr+4];
                    encoded[pixel_ptr+5] = uq -= encoded[pixel_ptr+5];
                    encoded[pixel_ptr+6] = vq -= encoded[pixel_ptr+6];
                    encoded[pixel_ptr+7] = vq -= encoded[pixel_ptr+7];
                    pixel_ptr += 8;
                }
            }
            break;
        case IMGTYPE_YUV411:
            for (row = 0; row < height; row++) {
                pixel_ptr = row * width / 2 * 3;
                yq = uq = vq =0;
                for (col = 0; col < width/4; col++) {
                    encoded[pixel_ptr] = yq -= encoded[pixel_ptr];
                    encoded[pixel_ptr+1] = yq -= encoded[pixel_ptr+1];