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ffmpeg / libavcodec / bethsoftvideo.c @ dc338d17

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/*
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 * Bethesda VID video decoder
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 * Copyright (C) 2007 Nicholas Tung
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; 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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 */
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/**
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 * @file bethsoftvideo.c
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 * @brief Bethesda Softworks VID Video Decoder
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 * @author Nicholas Tung [ntung (at. ntung com] (2007-03)
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 * @sa http://wiki.multimedia.cx/index.php?title=Bethsoft_VID
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 * @sa http://www.svatopluk.com/andux/docs/dfvid.html
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 */
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#include "common.h"
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#include "dsputil.h"
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#include "bethsoftvideo.h"
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#include "bytestream.h"
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typedef struct BethsoftvidContext {
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    AVFrame frame;
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} BethsoftvidContext;
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static int bethsoftvid_decode_init(AVCodecContext *avctx)
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{
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    BethsoftvidContext *vid = avctx->priv_data;
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    vid->frame.reference = 1;
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    vid->frame.buffer_hints = FF_BUFFER_HINTS_VALID |
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        FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
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    avctx->pix_fmt = PIX_FMT_PAL8;    // palette in vid->frame.data[1]
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    av_log(avctx, AV_LOG_DEBUG, "[bethsoftvid video decoder] init\n");
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    return 0;
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}
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static void set_palette(AVFrame * frame, uint8_t * palette_buffer)
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{
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    uint32_t * palette = (uint32_t *)frame->data[1];
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    int a;
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    for(a = 0; a < 256; a++){
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        palette[a] = AV_RB24(&palette_buffer[a * 3]) * 4;    // multiply all colors by 4
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    }
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    frame->palette_has_changed = 1;
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}
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static int bethsoftvid_decode_frame(AVCodecContext *avctx,
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                              void *data, int *data_size,
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                              uint8_t *buf, int buf_size)
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{
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    BethsoftvidContext * vid = avctx->priv_data;
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    char block_type;
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    uint8_t * destination;
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    uint8_t * frame_end;
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    int line_remaining = avctx->width;          // number of bytes remaining on a line
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    const int wrap_to_next_line = vid->frame.linesize[0] - avctx->width;
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    uint8_t rle_num_bytes;
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    int yoffset;
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    av_log(avctx, AV_LOG_DEBUG, "[bethsoftvid video decoder] decoding frame\n");
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    // reget buffer will copy old data, good for simple difference frames
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    if (avctx->reget_buffer(avctx, &vid->frame)) {
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        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
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        return -1;
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    }
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    destination = vid->frame.data[0];
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    frame_end = vid->frame.data[0] + vid->frame.linesize[0] * avctx->height;
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    switch(block_type = *buf++){
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        case PALETTE_BLOCK:
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            set_palette(&vid->frame, buf);
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            return 0;
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        case VIDEO_YOFF_P_FRAME:
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            yoffset = bytestream_get_le16(&buf);
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            if(yoffset >= avctx->height)
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                return -1;
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            destination += vid->frame.linesize[0] * yoffset;
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    }
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    // main code
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    while((rle_num_bytes = *buf++)){
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        int length = rle_num_bytes & 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 > line_remaining){
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            if(rle_num_bytes < 0x80)
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                bytestream_get_buffer(&buf, destination, line_remaining);
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            else if(block_type == VIDEO_I_FRAME)
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                memset(destination, buf[0], line_remaining);
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            length -= line_remaining;      // decrement the number of bytes to be copied
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            destination += line_remaining + wrap_to_next_line;    // skip over extra bytes at end of frame
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            line_remaining = avctx->width;
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            if(destination == frame_end)
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                goto end;
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        }
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        // copy any remaining bytes after / if line overflows
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        if(rle_num_bytes < 0x80)
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            bytestream_get_buffer(&buf, destination, length);
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        else if(block_type == VIDEO_I_FRAME)
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            memset(destination, *buf++, length);
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        line_remaining -= length;
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        destination += length;
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    }
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    end:
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    *data_size = sizeof(AVFrame);
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    *(AVFrame*)data = vid->frame;
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    return buf_size;
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}
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static int bethsoftvid_decode_end(AVCodecContext *avctx)
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{
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    BethsoftvidContext * vid = avctx->priv_data;
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    av_log(avctx, AV_LOG_DEBUG, "[bethsoftvid video decoder] closing\n");
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    if(vid->frame.data[0])
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        avctx->release_buffer(avctx, &vid->frame);
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    return 0;
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}
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AVCodec bethsoftvid_decoder = {
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    .name = "bethsoftvid",
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    .type = CODEC_TYPE_VIDEO,
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    .id = CODEC_ID_BETHSOFTVID,
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    .priv_data_size = sizeof(BethsoftvidContext),
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    .init = bethsoftvid_decode_init,
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    .close = bethsoftvid_decode_end,
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    .decode = bethsoftvid_decode_frame,
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};