bfi.c

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/*
 * Brute Force & Ignorance (BFI) video decoder
 * Copyright (c) 2008 Sisir Koppaka
 *
 * 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 bfi.c
 * @brief Brute Force & Ignorance (.bfi) video decoder
 * @author Sisir Koppaka ( sisir.koppaka at gmail dot com )
 * @sa http://wiki.multimedia.cx/index.php?title=BFI
 */

#include "libavutil/common.h"
#include "avcodec.h"
#include "bytestream.h"

typedef struct BFIContext {
    AVCodecContext *avctx;
    AVFrame frame;
    uint8_t *dst;
} BFIContext;

static int bfi_decode_init(AVCodecContext * avctx)
{
    BFIContext *bfi = avctx->priv_data;
    avctx->pix_fmt = PIX_FMT_PAL8;
    bfi->dst = av_mallocz(avctx->width * avctx->height);
    return 0;
}

static int bfi_decode_frame(AVCodecContext * avctx, void *data,
                            int *data_size, const uint8_t * buf,
                            int buf_size)
{
    BFIContext *bfi = avctx->priv_data;
    uint8_t *dst = bfi->dst;
    uint8_t *src, *dst_offset, colour1, colour2;
    uint8_t *frame_end = bfi->dst + avctx->width * avctx->height;
    uint32_t *pal;
    int i, j, height = avctx->height;

    if (bfi->frame.data[0])
        avctx->release_buffer(avctx, &bfi->frame);

    bfi->frame.reference = 1;

    if (avctx->get_buffer(avctx, &bfi->frame) < 0) {
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return -1;
    }

    /* Set frame parameters and palette, if necessary */
    if (!avctx->frame_number) {
        bfi->frame.pict_type = FF_I_TYPE;
        bfi->frame.key_frame = 1;
        /* Setting the palette */
        if(avctx->extradata_size>768) {
            av_log(NULL, AV_LOG_ERROR, "Palette is too large.\n");
            return -1;
        }
        pal = (uint32_t *) bfi->frame.data[1];
        for (i = 0; i < avctx->extradata_size / 3; i++) {
            int shift = 16;
            *pal = 0;
            for (j = 0; j < 3; j++, shift -= 8)
                *pal +=
                    ((avctx->extradata[i * 3 + j] << 2) |
                    (avctx->extradata[i * 3 + j] >> 4)) << shift;
            pal++;
        }
        bfi->frame.palette_has_changed = 1;
    } else {
        bfi->frame.pict_type = FF_P_TYPE;
        bfi->frame.key_frame = 0;
    }

    buf += 4; //Unpacked size, not required.

    while (dst != frame_end) {
        static const uint8_t lentab[4]={0,2,0,1};
        unsigned int byte = *buf++, offset;
        unsigned int code = byte >> 6;
        unsigned int length = byte & ~0xC0;

        /* Get length and offset(if required) */
        if (length == 0) {
            if (code == 1) {
                length = bytestream_get_byte(&buf);
                offset = bytestream_get_le16(&buf);
            } else {
                length = bytestream_get_le16(&buf);
                if (code == 2 && length == 0)
                    break;
            }
        } else {
            if (code == 1)
                offset = bytestream_get_byte(&buf);
        }

        /* Do boundary check */
        if (dst + (length<<lentab[code]) > frame_end)
            break;

        switch (code) {

        case 0:                //Normal Chain
            bytestream_get_buffer(&buf, dst, length);
            dst += length;
            break;

        case 1:                //Back Chain
            dst_offset = dst - offset;
            length *= 4;        //Convert dwords to bytes.
            if (dst_offset < bfi->dst)
                break;
            while (length--)
                *dst++ = *dst_offset++;
            break;

        case 2:                //Skip Chain
            dst += length;
            break;

        case 3:                //Fill Chain
            colour1 = bytestream_get_byte(&buf);
            colour2 = bytestream_get_byte(&buf);
            while (length--) {
                *dst++ = colour1;
                *dst++ = colour2;
            }
            break;

        }
    }

    src = bfi->dst;
    dst = bfi->frame.data[0];
    while (height--) {
        memcpy(dst, src, avctx->width);
        src += avctx->width;
        dst += bfi->frame.linesize[0];
    }
    *data_size = sizeof(AVFrame);
    *(AVFrame *) data = bfi->frame;
    return buf_size;
}

static int bfi_decode_close(AVCodecContext * avctx)
{
    BFIContext *bfi = avctx->priv_data;
    if (bfi->frame.data[0])
        avctx->release_buffer(avctx, &bfi->frame);
    av_free(bfi->dst);
    return 0;
}

AVCodec bfi_decoder = {
    .name = "bfi",
    .type = CODEC_TYPE_VIDEO,
    .id = CODEC_ID_BFI,
    .priv_data_size = sizeof(BFIContext),
    .init = bfi_decode_init,
    .close = bfi_decode_close,
    .decode = bfi_decode_frame,
    .long_name = NULL_IF_CONFIG_SMALL("Brute Force & Ignorance"),
};