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ffmpeg-4.2.2/libavcodec/tmv.c 2.79 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * 8088flex TMV video decoder
   * Copyright (c) 2009 Daniel Verkamp <daniel at drv.nu>
   *
   * 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
   * 8088flex TMV video decoder
   * @author Daniel Verkamp
   * @see http://www.oldskool.org/pc/8088_Corruption
   */
  
  #include <string.h>
  
  #include "avcodec.h"
  #include "internal.h"
  #include "libavutil/internal.h"
  #include "libavutil/xga_font_data.h"
  
  #include "cga_data.h"
  
  static int tmv_decode_frame(AVCodecContext *avctx, void *data,
                              int *got_frame, AVPacket *avpkt)
  {
      AVFrame *frame     = data;
      const uint8_t *src = avpkt->data;
      uint8_t *dst;
      unsigned char_cols = avctx->width >> 3;
      unsigned char_rows = avctx->height >> 3;
      unsigned x, y, fg, bg, c;
      int ret;
  
      if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
          return ret;
  
      if (avpkt->size < 2*char_rows*char_cols) {
          av_log(avctx, AV_LOG_ERROR,
                 "Input buffer too small, truncated sample?\n");
          *got_frame = 0;
          return AVERROR_INVALIDDATA;
      }
  
      frame->pict_type = AV_PICTURE_TYPE_I;
      frame->key_frame = 1;
      dst              = frame->data[0];
  
      frame->palette_has_changed = 1;
      memcpy(frame->data[1], ff_cga_palette, 16 * 4);
      memset(frame->data[1] + 16 * 4, 0, AVPALETTE_SIZE - 16 * 4);
  
      for (y = 0; y < char_rows; y++) {
          for (x = 0; x < char_cols; x++) {
              c  = *src++;
              bg = *src  >> 4;
              fg = *src++ & 0xF;
              ff_draw_pc_font(dst + x * 8, frame->linesize[0],
                              avpriv_cga_font, 8, c, fg, bg);
          }
          dst += frame->linesize[0] * 8;
      }
  
      *got_frame = 1;
  
      return avpkt->size;
  }
  
  static av_cold int tmv_decode_init(AVCodecContext *avctx)
  {
      avctx->pix_fmt = AV_PIX_FMT_PAL8;
      return 0;
  }
  
  AVCodec ff_tmv_decoder = {
      .name           = "tmv",
      .long_name      = NULL_IF_CONFIG_SMALL("8088flex TMV"),
      .type           = AVMEDIA_TYPE_VIDEO,
      .id             = AV_CODEC_ID_TMV,
      .init           = tmv_decode_init,
      .decode         = tmv_decode_frame,
      .capabilities   = AV_CODEC_CAP_DR1,
  };