1 /*
2 * FITS image decoder
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 decoder
25 *
26 * Specification: https://fits.gsfc.nasa.gov/fits_standard.html Version 3.0
27 *
28 * Support all 2d images alongwith, bzero, bscale and blank keywords.
29 * RGBA images are supported as NAXIS3 = 3 or 4 i.e. Planes in RGBA order. Also CTYPE = 'RGB ' should be present.
30 * Also to interpret data, values are linearly scaled using min-max scaling but not RGB images.
31 */
32
33 #include "avcodec.h"
34 #include "internal.h"
35 #include <float.h>
36 #include "libavutil/intreadwrite.h"
37 #include "libavutil/intfloat.h"
38 #include "libavutil/dict.h"
39 #include "libavutil/opt.h"
40 #include "fits.h"
41
42 typedef struct FITSContext {
43 const AVClass *class;
44 int blank_val;
45 } FITSContext;
46
47 /**
48 * Calculate the data_min and data_max values from the data.
49 * This is called if the values are not present in the header.
50 * @param ptr8 pointer to the data
51 * @param header pointer to the header
52 * @param end pointer to end of packet
53 * @return 0 if calculated successfully otherwise AVERROR_INVALIDDATA
54 */
fill_data_min_max(const uint8_t * ptr8,FITSHeader * header,const uint8_t * end)55 static int fill_data_min_max(const uint8_t *ptr8, FITSHeader *header, const uint8_t *end)
56 {
57 uint8_t t8;
58 int16_t t16;
59 int32_t t32;
60 int64_t t64;
61 float tflt;
62 double tdbl;
63 int i, j;
64
65 header->data_min = DBL_MAX;
66 header->data_max = -DBL_MAX;
67 switch (header->bitpix) {
68 #define CASE_N(a, t, rd) \
69 case a: \
70 for (i = 0; i < header->naxisn[1]; i++) { \
71 for (j = 0; j < header->naxisn[0]; j++) { \
72 t = rd; \
73 if (!header->blank_found || t != header->blank) { \
74 if (t > header->data_max) \
75 header->data_max = t; \
76 if (t < header->data_min) \
77 header->data_min = t; \
78 } \
79 ptr8 += abs(a) >> 3; \
80 } \
81 } \
82 break
83
84 CASE_N(-64, tdbl, av_int2double(AV_RB64(ptr8)));
85 CASE_N(-32, tflt, av_int2float(AV_RB32(ptr8)));
86 CASE_N(8, t8, ptr8[0]);
87 CASE_N(16, t16, AV_RB16(ptr8));
88 CASE_N(32, t32, AV_RB32(ptr8));
89 CASE_N(64, t64, AV_RB64(ptr8));
90 default:
91 return AVERROR_INVALIDDATA;
92 }
93 return 0;
94 }
95
96 /**
97 * Read the fits header and store the values in FITSHeader pointed by header
98 * @param avctx AVCodec context
99 * @param ptr pointer to pointer to the data
100 * @param header pointer to the FITSHeader
101 * @param end pointer to end of packet
102 * @param metadata pointer to pointer to AVDictionary to store metadata
103 * @return 0 if calculated successfully otherwise AVERROR_INVALIDDATA
104 */
fits_read_header(AVCodecContext * avctx,const uint8_t ** ptr,FITSHeader * header,const uint8_t * end,AVDictionary ** metadata)105 static int fits_read_header(AVCodecContext *avctx, const uint8_t **ptr, FITSHeader *header,
106 const uint8_t *end, AVDictionary **metadata)
107 {
108 const uint8_t *ptr8 = *ptr;
109 int lines_read, bytes_left, i, ret;
110 size_t size;
111
112 lines_read = 1; // to account for first header line, SIMPLE or XTENSION which is not included in packet...
113 avpriv_fits_header_init(header, STATE_BITPIX);
114 do {
115 if (end - ptr8 < 80)
116 return AVERROR_INVALIDDATA;
117 ret = avpriv_fits_header_parse_line(avctx, header, ptr8, &metadata);
118 ptr8 += 80;
119 lines_read++;
120 } while (!ret);
121 if (ret < 0)
122 return ret;
123
124 bytes_left = (((lines_read + 35) / 36) * 36 - lines_read) * 80;
125 if (end - ptr8 < bytes_left)
126 return AVERROR_INVALIDDATA;
127 ptr8 += bytes_left;
128
129 if (header->rgb && (header->naxis != 3 || (header->naxisn[2] != 3 && header->naxisn[2] != 4))) {
130 av_log(avctx, AV_LOG_ERROR, "File contains RGB image but NAXIS = %d and NAXIS3 = %d\n", header->naxis, header->naxisn[2]);
131 return AVERROR_INVALIDDATA;
132 }
133
134 if (!header->rgb && header->naxis != 2) {
135 av_log(avctx, AV_LOG_ERROR, "unsupported number of dimensions, NAXIS = %d\n", header->naxis);
136 return AVERROR_INVALIDDATA;
137 }
138
139 if (header->blank_found && (header->bitpix == -32 || header->bitpix == -64)) {
140 av_log(avctx, AV_LOG_WARNING, "BLANK keyword found but BITPIX = %d\n. Ignoring BLANK", header->bitpix);
141 header->blank_found = 0;
142 }
143
144 size = abs(header->bitpix) >> 3;
145 for (i = 0; i < header->naxis; i++) {
146 if (size == 0 || header->naxisn[i] > SIZE_MAX / size) {
147 av_log(avctx, AV_LOG_ERROR, "unsupported size of FITS image");
148 return AVERROR_INVALIDDATA;
149 }
150 size *= header->naxisn[i];
151 }
152
153 if (end - ptr8 < size)
154 return AVERROR_INVALIDDATA;
155 *ptr = ptr8;
156
157 if (!header->rgb && (!header->data_min_found || !header->data_max_found)) {
158 ret = fill_data_min_max(ptr8, header, end);
159 if (ret < 0) {
160 av_log(avctx, AV_LOG_ERROR, "invalid BITPIX, %d\n", header->bitpix);
161 return ret;
162 }
163 } else {
164 /*
165 * instead of applying bscale and bzero to every element,
166 * we can do inverse transformation on data_min and data_max
167 */
168 header->data_min = (header->data_min - header->bzero) / header->bscale;
169 header->data_max = (header->data_max - header->bzero) / header->bscale;
170 }
171 if (!header->rgb && header->data_min >= header->data_max) {
172 if (header->data_min > header->data_max) {
173 av_log(avctx, AV_LOG_ERROR, "data min/max (%g %g) is invalid\n", header->data_min, header->data_max);
174 return AVERROR_INVALIDDATA;
175 }
176 av_log(avctx, AV_LOG_WARNING, "data min/max indicates a blank image\n");
177 header->data_max ++;
178 }
179
180 return 0;
181 }
182
fits_decode_frame(AVCodecContext * avctx,void * data,int * got_frame,AVPacket * avpkt)183 static int fits_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
184 {
185 AVFrame *p=data;
186 const uint8_t *ptr8 = avpkt->data, *end;
187 uint8_t t8;
188 int16_t t16;
189 int32_t t32;
190 int64_t t64;
191 float tflt;
192 double tdbl;
193 int ret, i, j, k;
194 const int map[] = {2, 0, 1, 3}; // mapping from GBRA -> RGBA as RGBA is to be stored in FITS file..
195 uint8_t *dst8;
196 uint16_t *dst16;
197 uint64_t t;
198 FITSHeader header;
199 FITSContext * fitsctx = avctx->priv_data;
200
201 end = ptr8 + avpkt->size;
202 p->metadata = NULL;
203 ret = fits_read_header(avctx, &ptr8, &header, end, &p->metadata);
204 if (ret < 0)
205 return ret;
206
207 if (header.rgb) {
208 if (header.bitpix == 8) {
209 if (header.naxisn[2] == 3) {
210 avctx->pix_fmt = AV_PIX_FMT_GBRP;
211 } else {
212 avctx->pix_fmt = AV_PIX_FMT_GBRAP;
213 }
214 } else if (header.bitpix == 16) {
215 if (header.naxisn[2] == 3) {
216 avctx->pix_fmt = AV_PIX_FMT_GBRP16;
217 } else {
218 avctx->pix_fmt = AV_PIX_FMT_GBRAP16;
219 }
220 } else {
221 av_log(avctx, AV_LOG_ERROR, "unsupported BITPIX = %d\n", header.bitpix);
222 return AVERROR_INVALIDDATA;
223 }
224 } else {
225 if (header.bitpix == 8) {
226 avctx->pix_fmt = AV_PIX_FMT_GRAY8;
227 } else {
228 avctx->pix_fmt = AV_PIX_FMT_GRAY16;
229 }
230 }
231
232 if ((ret = ff_set_dimensions(avctx, header.naxisn[0], header.naxisn[1])) < 0)
233 return ret;
234
235 if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
236 return ret;
237
238 /*
239 * FITS stores images with bottom row first. Therefore we have
240 * to fill the image from bottom to top.
241 */
242 if (header.rgb) {
243 switch(header.bitpix) {
244 #define CASE_RGB(cas, dst, type, dref) \
245 case cas: \
246 for (k = 0; k < header.naxisn[2]; k++) { \
247 for (i = 0; i < avctx->height; i++) { \
248 dst = (type *) (p->data[map[k]] + (avctx->height - i - 1) * p->linesize[map[k]]); \
249 for (j = 0; j < avctx->width; j++) { \
250 t32 = dref(ptr8); \
251 if (!header.blank_found || t32 != header.blank) { \
252 t = t32 * header.bscale + header.bzero; \
253 } else { \
254 t = fitsctx->blank_val; \
255 } \
256 *dst++ = (type) t; \
257 ptr8 += cas >> 3; \
258 } \
259 } \
260 } \
261 break
262
263 CASE_RGB(8, dst8, uint8_t, *);
264 CASE_RGB(16, dst16, uint16_t, AV_RB16);
265 }
266 } else {
267 double scale = header.data_max - header.data_min;
268
269 if (scale <= 0 || !isfinite(scale)) {
270 scale = 1;
271 }
272 scale = 1/scale;
273
274 switch (header.bitpix) {
275 #define CASE_GRAY(cas, dst, type, t, rd) \
276 case cas: \
277 for (i = 0; i < avctx->height; i++) { \
278 dst = (type *) (p->data[0] + (avctx->height-i-1)* p->linesize[0]); \
279 for (j = 0; j < avctx->width; j++) { \
280 t = rd; \
281 if (!header.blank_found || t != header.blank) { \
282 *dst++ = lrint(((t - header.data_min) * ((1 << (sizeof(type) * 8)) - 1)) * scale); \
283 } else { \
284 *dst++ = fitsctx->blank_val; \
285 } \
286 ptr8 += abs(cas) >> 3; \
287 } \
288 } \
289 break
290
291 CASE_GRAY(-64, dst16, uint16_t, tdbl, av_int2double(AV_RB64(ptr8)));
292 CASE_GRAY(-32, dst16, uint16_t, tflt, av_int2float(AV_RB32(ptr8)));
293 CASE_GRAY(8, dst8, uint8_t, t8, ptr8[0]);
294 CASE_GRAY(16, dst16, uint16_t, t16, AV_RB16(ptr8));
295 CASE_GRAY(32, dst16, uint16_t, t32, AV_RB32(ptr8));
296 CASE_GRAY(64, dst16, uint16_t, t64, AV_RB64(ptr8));
297 default:
298 av_log(avctx, AV_LOG_ERROR, "invalid BITPIX, %d\n", header.bitpix);
299 return AVERROR_INVALIDDATA;
300 }
301 }
302
303 p->key_frame = 1;
304 p->pict_type = AV_PICTURE_TYPE_I;
305
306 *got_frame = 1;
307
308 return avpkt->size;
309 }
310
311 static const AVOption fits_options[] = {
312 { "blank_value", "value that is used to replace BLANK pixels in data array", offsetof(FITSContext, blank_val), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 65535, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_VIDEO_PARAM},
313 { NULL },
314 };
315
316 static const AVClass fits_decoder_class = {
317 .class_name = "FITS decoder",
318 .item_name = av_default_item_name,
319 .option = fits_options,
320 .version = LIBAVUTIL_VERSION_INT,
321 };
322
323 AVCodec ff_fits_decoder = {
324 .name = "fits",
325 .type = AVMEDIA_TYPE_VIDEO,
326 .id = AV_CODEC_ID_FITS,
327 .priv_data_size = sizeof(FITSContext),
328 .decode = fits_decode_frame,
329 .capabilities = AV_CODEC_CAP_DR1,
330 .long_name = NULL_IF_CONFIG_SMALL("Flexible Image Transport System"),
331 .priv_class = &fits_decoder_class
332 };
333