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ffmpeg-4.2.2/libavcodec/fitsenc.c 4.32 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * FITS image encoder
   * Copyright (c) 2017 Paras Chadha
   *
   * 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
   * FITS image encoder
   *
   * Specification: https://fits.gsfc.nasa.gov/fits_standard.html Version 3.0
   *
   * RGBA images are encoded as planes in RGBA order. So, NAXIS3 is 3 or 4 for them.
   * Also CTYPE3 = 'RGB ' is added to the header to distinguish them from 3d images.
   */
  
  #include "libavutil/intreadwrite.h"
  #include "avcodec.h"
  #include "bytestream.h"
  #include "internal.h"
  
  static int fits_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                              const AVFrame *pict, int *got_packet)
  {
      AVFrame * const p = (AVFrame *)pict;
      uint8_t *bytestream, *bytestream_start, *ptr;
      const uint16_t flip = (1 << 15);
      uint64_t data_size = 0, padded_data_size = 0;
      int ret, bitpix, naxis3 = 1, i, j, k, bytes_left;
      int map[] = {2, 0, 1, 3}; // mapping from GBRA -> RGBA as RGBA is to be stored in FITS file..
  
      switch (avctx->pix_fmt) {
      case AV_PIX_FMT_GRAY8:
      case AV_PIX_FMT_GRAY16BE:
          map[0] = 0; // grayscale images should be directly mapped
          if (avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
              bitpix = 8;
          } else {
              bitpix = 16;
          }
          break;
      case AV_PIX_FMT_GBRP:
      case AV_PIX_FMT_GBRAP:
          bitpix = 8;
          if (avctx->pix_fmt == AV_PIX_FMT_GBRP) {
              naxis3 = 3;
          } else {
              naxis3 = 4;
          }
          break;
      case AV_PIX_FMT_GBRP16BE:
      case AV_PIX_FMT_GBRAP16BE:
          bitpix = 16;
          if (avctx->pix_fmt == AV_PIX_FMT_GBRP16BE) {
              naxis3 = 3;
          } else {
              naxis3 = 4;
          }
          break;
      default:
          av_log(avctx, AV_LOG_ERROR, "unsupported pixel format\n");
          return AVERROR(EINVAL);
      }
  
      data_size = (bitpix >> 3) * avctx->height * avctx->width * naxis3;
      padded_data_size = ((data_size + 2879) / 2880 ) * 2880;
  
      if ((ret = ff_alloc_packet2(avctx, pkt, padded_data_size, 0)) < 0)
          return ret;
  
      bytestream_start =
      bytestream       = pkt->data;
  
      for (k = 0; k < naxis3; k++) {
          for (i = 0; i < avctx->height; i++) {
              ptr = p->data[map[k]] + (avctx->height - i - 1) * p->linesize[map[k]];
              if (bitpix == 16) {
                  for (j = 0; j < avctx->width; j++) {
                      // subtracting bzero is equivalent to first bit flip
                      bytestream_put_be16(&bytestream, AV_RB16(ptr) ^ flip);
                      ptr += 2;
                  }
              } else {
                  memcpy(bytestream, ptr, avctx->width);
                  bytestream += avctx->width;
              }
          }
      }
  
      bytes_left = padded_data_size - data_size;
      memset(bytestream, 0, bytes_left);
      bytestream += bytes_left;
  
      pkt->size   = bytestream - bytestream_start;
      pkt->flags |= AV_PKT_FLAG_KEY;
      *got_packet = 1;
  
      return 0;
  }
  
  AVCodec ff_fits_encoder = {
      .name           = "fits",
      .long_name      = NULL_IF_CONFIG_SMALL("Flexible Image Transport System"),
      .type           = AVMEDIA_TYPE_VIDEO,
      .id             = AV_CODEC_ID_FITS,
      .encode2        = fits_encode_frame,
      .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_GBRAP16BE,
                                                       AV_PIX_FMT_GBRP16BE,
                                                       AV_PIX_FMT_GBRP,
                                                       AV_PIX_FMT_GBRAP,
                                                       AV_PIX_FMT_GRAY16BE,
                                                       AV_PIX_FMT_GRAY8,
                                                       AV_PIX_FMT_NONE },
  };