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1 /*
2  * FITS image encoder
3  * Copyright (c) 2017 Paras Chadha
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * FITS image encoder
25  *
26  * Specification: https://fits.gsfc.nasa.gov/fits_standard.html Version 3.0
27  *
28  * RGBA images are encoded as planes in RGBA order. So, NAXIS3 is 3 or 4 for them.
29  * Also CTYPE3 = 'RGB ' is added to the header to distinguish them from 3d images.
30  */
31 
32 #include "libavutil/intreadwrite.h"
33 #include "avcodec.h"
34 #include "bytestream.h"
35 #include "internal.h"
36 
fits_encode_frame(AVCodecContext * avctx,AVPacket * pkt,const AVFrame * pict,int * got_packet)37 static int fits_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
38                             const AVFrame *pict, int *got_packet)
39 {
40     AVFrame * const p = (AVFrame *)pict;
41     uint8_t *bytestream, *bytestream_start, *ptr;
42     const uint16_t flip = (1 << 15);
43     uint64_t data_size = 0, padded_data_size = 0;
44     int ret, bitpix, naxis3 = 1, i, j, k, bytes_left;
45     int map[] = {2, 0, 1, 3}; // mapping from GBRA -> RGBA as RGBA is to be stored in FITS file..
46 
47     switch (avctx->pix_fmt) {
48     case AV_PIX_FMT_GRAY8:
49     case AV_PIX_FMT_GRAY16BE:
50         map[0] = 0; // grayscale images should be directly mapped
51         if (avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
52             bitpix = 8;
53         } else {
54             bitpix = 16;
55         }
56         break;
57     case AV_PIX_FMT_GBRP:
58     case AV_PIX_FMT_GBRAP:
59         bitpix = 8;
60         if (avctx->pix_fmt == AV_PIX_FMT_GBRP) {
61             naxis3 = 3;
62         } else {
63             naxis3 = 4;
64         }
65         break;
66     case AV_PIX_FMT_GBRP16BE:
67     case AV_PIX_FMT_GBRAP16BE:
68         bitpix = 16;
69         if (avctx->pix_fmt == AV_PIX_FMT_GBRP16BE) {
70             naxis3 = 3;
71         } else {
72             naxis3 = 4;
73         }
74         break;
75     default:
76         av_log(avctx, AV_LOG_ERROR, "unsupported pixel format\n");
77         return AVERROR(EINVAL);
78     }
79 
80     data_size = (bitpix >> 3) * avctx->height * avctx->width * naxis3;
81     padded_data_size = ((data_size + 2879) / 2880 ) * 2880;
82 
83     if ((ret = ff_alloc_packet2(avctx, pkt, padded_data_size, 0)) < 0)
84         return ret;
85 
86     bytestream_start =
87     bytestream       = pkt->data;
88 
89     for (k = 0; k < naxis3; k++) {
90         for (i = 0; i < avctx->height; i++) {
91             ptr = p->data[map[k]] + (avctx->height - i - 1) * p->linesize[map[k]];
92             if (bitpix == 16) {
93                 for (j = 0; j < avctx->width; j++) {
94                     // subtracting bzero is equivalent to first bit flip
95                     bytestream_put_be16(&bytestream, AV_RB16(ptr) ^ flip);
96                     ptr += 2;
97                 }
98             } else {
99                 memcpy(bytestream, ptr, avctx->width);
100                 bytestream += avctx->width;
101             }
102         }
103     }
104 
105     bytes_left = padded_data_size - data_size;
106     memset(bytestream, 0, bytes_left);
107     bytestream += bytes_left;
108 
109     pkt->size   = bytestream - bytestream_start;
110     pkt->flags |= AV_PKT_FLAG_KEY;
111     *got_packet = 1;
112 
113     return 0;
114 }
115 
116 AVCodec ff_fits_encoder = {
117     .name           = "fits",
118     .long_name      = NULL_IF_CONFIG_SMALL("Flexible Image Transport System"),
119     .type           = AVMEDIA_TYPE_VIDEO,
120     .id             = AV_CODEC_ID_FITS,
121     .encode2        = fits_encode_frame,
122     .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_GBRAP16BE,
123                                                      AV_PIX_FMT_GBRP16BE,
124                                                      AV_PIX_FMT_GBRP,
125                                                      AV_PIX_FMT_GBRAP,
126                                                      AV_PIX_FMT_GRAY16BE,
127                                                      AV_PIX_FMT_GRAY8,
128                                                      AV_PIX_FMT_NONE },
129 };
130