bethsoftvideo.c 5.24 KB
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/*
 * Bethesda VID video decoder
 * Copyright (C) 2007 Nicholas Tung
 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * 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.
 *
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 * Libav is distributed in the hope that it will be useful,
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 * 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
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
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 * @file
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 * @brief Bethesda Softworks VID Video Decoder
 * @author Nicholas Tung [ntung (at. ntung com] (2007-03)
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 * @see http://wiki.multimedia.cx/index.php?title=Bethsoft_VID
 * @see http://www.svatopluk.com/andux/docs/dfvid.html
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 */

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#include "libavutil/common.h"
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#include "avcodec.h"
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#include "bethsoftvideo.h"
#include "bytestream.h"
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#include "internal.h"
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typedef struct BethsoftvidContext {
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    AVFrame *frame;
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    GetByteContext g;
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} BethsoftvidContext;

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static av_cold int bethsoftvid_decode_init(AVCodecContext *avctx)
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{
    BethsoftvidContext *vid = avctx->priv_data;
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    avctx->pix_fmt = AV_PIX_FMT_PAL8;
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    vid->frame = av_frame_alloc();
    if (!vid->frame)
        return AVERROR(ENOMEM);

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    return 0;
}

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static int set_palette(BethsoftvidContext *ctx)
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{
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    uint32_t *palette = (uint32_t *)ctx->frame->data[1];
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    int a;
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    if (bytestream2_get_bytes_left(&ctx->g) < 256*3)
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        return AVERROR_INVALIDDATA;

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    for(a = 0; a < 256; a++){
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        palette[a] = bytestream2_get_be24u(&ctx->g) * 4;
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    }
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    ctx->frame->palette_has_changed = 1;
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    return 0;
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}

static int bethsoftvid_decode_frame(AVCodecContext *avctx,
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                              void *data, int *got_frame,
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                              AVPacket *avpkt)
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{
    BethsoftvidContext * vid = avctx->priv_data;
    char block_type;
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    uint8_t * dst;
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    uint8_t * frame_end;
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    int remaining = avctx->width;          // number of bytes remaining on a line
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    int wrap_to_next_line;
    int code, ret;
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    int yoffset;

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    if ((ret = ff_reget_buffer(avctx, vid->frame)) < 0) {
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        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
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        return ret;
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    }
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    wrap_to_next_line = vid->frame->linesize[0] - avctx->width;
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    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;
    }
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    bytestream2_init(&vid->g, avpkt->data, avpkt->size);
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    dst = vid->frame->data[0];
    frame_end = vid->frame->data[0] + vid->frame->linesize[0] * avctx->height;
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    switch(block_type = bytestream2_get_byte(&vid->g)){
        case PALETTE_BLOCK: {
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            *got_frame = 0;
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            if ((ret = set_palette(vid)) < 0) {
                av_log(avctx, AV_LOG_ERROR, "error reading palette\n");
                return ret;
            }
            return bytestream2_tell(&vid->g);
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        }
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        case VIDEO_YOFF_P_FRAME:
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            yoffset = bytestream2_get_le16(&vid->g);
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            if(yoffset >= avctx->height)
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                return AVERROR_INVALIDDATA;
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            dst += vid->frame->linesize[0] * yoffset;
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    }

    // main code
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    while((code = bytestream2_get_byte(&vid->g))){
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        int length = code & 0x7f;
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        // copy any bytes starting at the current position, and ending at the frame width
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        while(length > remaining){
            if(code < 0x80)
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                bytestream2_get_buffer(&vid->g, dst, remaining);
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            else if(block_type == VIDEO_I_FRAME)
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                memset(dst, bytestream2_peek_byte(&vid->g), remaining);
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            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)
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                goto end;
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        }

        // copy any remaining bytes after / if line overflows
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        if(code < 0x80)
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            bytestream2_get_buffer(&vid->g, dst, length);
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        else if(block_type == VIDEO_I_FRAME)
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            memset(dst, bytestream2_get_byte(&vid->g), length);
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        remaining -= length;
        dst += length;
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    }
    end:

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

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    *got_frame = 1;
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    return avpkt->size;
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}

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static av_cold int bethsoftvid_decode_end(AVCodecContext *avctx)
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{
    BethsoftvidContext * vid = avctx->priv_data;
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    av_frame_free(&vid->frame);
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    return 0;
}

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AVCodec ff_bethsoftvid_decoder = {
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    .name           = "bethsoftvid",
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    .long_name      = NULL_IF_CONFIG_SMALL("Bethesda VID video"),
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    .type           = AVMEDIA_TYPE_VIDEO,
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    .id             = AV_CODEC_ID_BETHSOFTVID,
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    .priv_data_size = sizeof(BethsoftvidContext),
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    .init           = bethsoftvid_decode_init,
    .close          = bethsoftvid_decode_end,
    .decode         = bethsoftvid_decode_frame,
    .capabilities   = CODEC_CAP_DR1,
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};