PeerStreamer

/*

 * 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)

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

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

 */

#include "libavutil/common.h"

#include "dsputil.h"

#include "bethsoftvideo.h"

#include "bytestream.h"

typedef struct BethsoftvidContext {

    AVFrame frame;

} BethsoftvidContext;

static av_cold int bethsoftvid_decode_init(AVCodecContext *avctx)

{

    BethsoftvidContext *vid = avctx->priv_data;

    vid->frame.reference = 1;

    vid->frame.buffer_hints = FF_BUFFER_HINTS_VALID |

        FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;

    avctx->pix_fmt = PIX_FMT_PAL8;

    return 0;

}

static void set_palette(AVFrame * frame, const uint8_t * palette_buffer)

{

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

    int a;

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

        palette[a] = AV_RB24(&palette_buffer[a * 3]) * 4;

    }

    frame->palette_has_changed = 1;

}

static int bethsoftvid_decode_frame(AVCodecContext *avctx,

                              void *data, int *data_size,

                              AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    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

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

    int code;

    int yoffset;

    if (avctx->reget_buffer(avctx, &vid->frame)) {

        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");

        return -1;

    }

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

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

    switch(block_type = *buf++){

        case PALETTE_BLOCK:

            set_palette(&vid->frame, buf);

            return 0;

        case VIDEO_YOFF_P_FRAME:

            yoffset = bytestream_get_le16(&buf);

            if(yoffset >= avctx->height)

                return -1;

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

    }

    // main code

    while((code = *buf++)){

        int length = code & 0x7f;

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

        while(length > remaining){

            if(code < 0x80)

                bytestream_get_buffer(&buf, dst, remaining);

            else if(block_type == VIDEO_I_FRAME)

                memset(dst, buf[0], 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)

            bytestream_get_buffer(&buf, dst, length);

        else if(block_type == VIDEO_I_FRAME)

            memset(dst, *buf++, length);

        remaining -= length;

        dst += length;

    }

    end:

    *data_size = sizeof(AVFrame);

    *(AVFrame*)data = vid->frame;

    return buf_size;

}

static av_cold int bethsoftvid_decode_end(AVCodecContext *avctx)

{

    BethsoftvidContext * vid = avctx->priv_data;

    if(vid->frame.data[0])

        avctx->release_buffer(avctx, &vid->frame);

    return 0;

}

AVCodec ff_bethsoftvid_decoder = {

    .name = "bethsoftvid",

    .type = AVMEDIA_TYPE_VIDEO,

    .id = CODEC_ID_BETHSOFTVID,

    .priv_data_size = sizeof(BethsoftvidContext),

    .init = bethsoftvid_decode_init,

    .close = bethsoftvid_decode_end,

    .decode = bethsoftvid_decode_frame,

    .capabilities = CODEC_CAP_DR1,

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

};