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/*

 * Bethesda VID video decoder

 * Copyright (C) 2007 Nicholas Tung

 *

 * 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

 * @brief Bethesda Softworks VID Video Decoder

 * @author Nicholas Tung [ntung (at. ntung com] (2007-03)

 * @see http://wiki.multimedia.cx/index.php?title=Bethsoft_VID

 * @see http://www.svatopluk.com/andux/docs/dfvid.html

 */

#include "libavutil/common.h"

#include "avcodec.h"

#include "bethsoftvideo.h"

#include "bytestream.h"

#include "internal.h"

typedef struct BethsoftvidContext {

    AVFrame *frame;

    GetByteContext g;

} BethsoftvidContext;

static av_cold int bethsoftvid_decode_init(AVCodecContext *avctx)

{

    BethsoftvidContext *vid = avctx->priv_data;

    avctx->pix_fmt = AV_PIX_FMT_PAL8;

    vid->frame = av_frame_alloc();

    if (!vid->frame)

        return AVERROR(ENOMEM);

    return 0;

}

static int set_palette(BethsoftvidContext *ctx)

{

    uint32_t *palette = (uint32_t *)ctx->frame->data[1];

    int a;

    if (bytestream2_get_bytes_left(&ctx->g) < 256*3)

        return AVERROR_INVALIDDATA;

    for(a = 0; a < 256; a++){

        palette[a] = 0xFFU << 24 | bytestream2_get_be24u(&ctx->g) * 4;

        palette[a] |= palette[a] >> 6 & 0x30303;

    }

    ctx->frame->palette_has_changed = 1;

    return 0;

}

static int bethsoftvid_decode_frame(AVCodecContext *avctx,

                              void *data, int *got_frame,

                              AVPacket *avpkt)

{

    BethsoftvidContext * vid = avctx->priv_data;

    char block_type;

    uint8_t * dst;

    uint8_t * frame_end;

    int remaining = avctx->width;          // number of bytes remaining on a line

    int wrap_to_next_line;

    int code, ret;

    int yoffset;

    if ((ret = ff_reget_buffer(avctx, vid->frame)) < 0)

        return ret;

    wrap_to_next_line = vid->frame->linesize[0] - avctx->width;

    if (avpkt->side_data_elems > 0 &&

        avpkt->side_data[0].type == AV_PKT_DATA_PALETTE) {

        bytestream2_init(&vid->g, avpkt->side_data[0].data,

                         avpkt->side_data[0].size);

        if ((ret = set_palette(vid)) < 0)

            return ret;

    }

    bytestream2_init(&vid->g, avpkt->data, avpkt->size);

    dst = vid->frame->data[0];

    frame_end = vid->frame->data[0] + vid->frame->linesize[0] * avctx->height;

    switch(block_type = bytestream2_get_byte(&vid->g)){

        case PALETTE_BLOCK: {

            *got_frame = 0;

            if ((ret = set_palette(vid)) < 0) {

                av_log(avctx, AV_LOG_ERROR, "error reading palette\n");

                return ret;

            }

            return bytestream2_tell(&vid->g);

        }

        case VIDEO_YOFF_P_FRAME:

            yoffset = bytestream2_get_le16(&vid->g);

            if(yoffset >= avctx->height)

                return AVERROR_INVALIDDATA;

            dst += vid->frame->linesize[0] * yoffset;

    }

    // main code

    while((code = bytestream2_get_byte(&vid->g))){

        int length = code & 0x7f;

        // copy any bytes starting at the current position, and ending at the frame width

        while(length > remaining){

            if(code < 0x80)

                bytestream2_get_buffer(&vid->g, dst, remaining);

            else if(block_type == VIDEO_I_FRAME)

                memset(dst, bytestream2_peek_byte(&vid->g), remaining);

            length -= remaining;      // decrement the number of bytes to be copied

            dst += remaining + wrap_to_next_line;    // skip over extra bytes at end of frame

            remaining = avctx->width;

            if(dst == frame_end)

                goto end;

        }

        // copy any remaining bytes after / if line overflows

        if(code < 0x80)

            bytestream2_get_buffer(&vid->g, dst, length);

        else if(block_type == VIDEO_I_FRAME)

            memset(dst, bytestream2_get_byte(&vid->g), length);

        remaining -= length;

        dst += length;

    }

    end:

    if ((ret = av_frame_ref(data, vid->frame)) < 0)

        return ret;

    *got_frame = 1;

    return avpkt->size;

}

static av_cold int bethsoftvid_decode_end(AVCodecContext *avctx)

{

    BethsoftvidContext * vid = avctx->priv_data;

    av_frame_free(&vid->frame);

    return 0;

}

AVCodec ff_bethsoftvid_decoder = {

    .name           = "bethsoftvid",

    .long_name      = NULL_IF_CONFIG_SMALL("Bethesda VID video"),

    .type           = AVMEDIA_TYPE_VIDEO,

    .id             = AV_CODEC_ID_BETHSOFTVID,

    .priv_data_size = sizeof(BethsoftvidContext),

    .init           = bethsoftvid_decode_init,

    .close          = bethsoftvid_decode_end,

    .decode         = bethsoftvid_decode_frame,

    .capabilities   = AV_CODEC_CAP_DR1,

};