Add FITS Decoder

Signed-off-by: Paras Chadha <paraschadha18@gmail.com>

1 files changed, 203 insertions, 0 deletions

diff --git a/libavcodec/fits.c b/libavcodec/fits.c
new file mode 100644
index 0000000..365347f
--- /dev/null
+++ b/libavcodec/fits.c
@@ -0,0 +1,203 @@
+/*
+ * FITS implementation of common functions
+ * 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
+ */
+
+#include "avcodec.h"
+#include "libavutil/dict.h"
+#include "fits.h"
+
+int avpriv_fits_header_init(FITSHeader *header, FITSHeaderState state)
+{
+    header->state = state;
+    header->naxis_index = 0;
+    header->blank_found = 0;
+    header->pcount = 0;
+    header->gcount = 1;
+    header->groups = 0;
+    header->rgb = 0;
+    header->image_extension = 0;
+    header->bscale = 1.0;
+    header->bzero = 0;
+    header->data_min_found = 0;
+    header->data_max_found = 0;
+    return 0;
+}
+
+static int dict_set_if_not_null(AVDictionary ***metadata, char *keyword, char *value)
+{
+    if (metadata)
+        av_dict_set(*metadata, keyword, value, 0);
+    return 0;
+}
+
+/**
+ * Extract keyword and value from a header line (80 bytes) and store them in keyword and value strings respectively
+ * @param ptr8 pointer to the data
+ * @param keyword pointer to the char array in which keyword is to be stored
+ * @param value pointer to the char array in which value is to be stored
+ * @return 0 if calculated successfully otherwise AVERROR_INVALIDDATA
+ */
+static int read_keyword_value(const uint8_t *ptr8, char *keyword, char *value)
+{
+    int i;
+
+    for (i = 0; i < 8 && ptr8[i] != ' '; i++) {
+        keyword[i] = ptr8[i];
+    }
+    keyword[i] = '\0';
+
+    if (ptr8[8] == '=') {
+        i = 10;
+        while (i < 80 && ptr8[i] == ' ') {
+            i++;
+        }
+
+        if (i < 80) {
+            *value++ = ptr8[i];
+            i++;
+            if (ptr8[i-1] == '\'') {
+                for (; i < 80 && ptr8[i] != '\''; i++) {
+                    *value++ = ptr8[i];
+                }
+                *value++ = '\'';
+            } else if (ptr8[i-1] == '(') {
+                for (; i < 80 && ptr8[i] != ')'; i++) {
+                    *value++ = ptr8[i];
+                }
+                *value++ = ')';
+            } else {
+                for (; i < 80 && ptr8[i] != ' ' && ptr8[i] != '/'; i++) {
+                    *value++ = ptr8[i];
+                }
+            }
+        }
+    }
+    *value = '\0';
+    return 0;
+}
+
+#define CHECK_KEYWORD(key) \
+    if (strcmp(keyword, key)) { \
+        av_log(avcl, AV_LOG_ERROR, "expected %s keyword, found %s = %s\n", key, keyword, value); \
+        return AVERROR_INVALIDDATA; \
+    }
+
+#define CHECK_VALUE(key, val) \
+    if (sscanf(value, "%d", &header->val) != 1) { \
+        av_log(avcl, AV_LOG_ERROR, "invalid value of %s keyword, %s = %s\n", key, keyword, value); \
+        return AVERROR_INVALIDDATA; \
+    }
+
+int avpriv_fits_header_parse_line(void *avcl, FITSHeader *header, const uint8_t line[80], AVDictionary ***metadata)
+{
+    int dim_no, ret;
+    int64_t t;
+    double d;
+    char keyword[10], value[72], c;
+
+    read_keyword_value(line, keyword, value);
+    switch (header->state) {
+    case STATE_SIMPLE:
+        CHECK_KEYWORD("SIMPLE");
+
+        if (value[0] == 'F') {
+            av_log(avcl, AV_LOG_WARNING, "not a standard FITS file\n");
+        } else if (value[0] != 'T') {
+            av_log(avcl, AV_LOG_ERROR, "invalid value of SIMPLE keyword, SIMPLE = %c\n", value[0]);
+            return AVERROR_INVALIDDATA;
+        }
+
+        header->state = STATE_BITPIX;
+        break;
+    case STATE_XTENSION:
+        CHECK_KEYWORD("XTENSION");
+
+        if (!strcmp(value, "'IMAGE   '")) {
+            header->image_extension = 1;
+        }
+
+        header->state = STATE_BITPIX;
+        break;
+    case STATE_BITPIX:
+        CHECK_KEYWORD("BITPIX");
+        CHECK_VALUE("BITPIX", bitpix);
+        dict_set_if_not_null(metadata, keyword, value);
+
+        header->state = STATE_NAXIS;
+        break;
+    case STATE_NAXIS:
+        CHECK_KEYWORD("NAXIS");
+        CHECK_VALUE("NAXIS", naxis);
+        dict_set_if_not_null(metadata, keyword, value);
+
+        if (header->naxis) {
+            header->state = STATE_NAXIS_N;
+        } else {
+            header->state = STATE_REST;
+        }
+        break;
+    case STATE_NAXIS_N:
+        ret = sscanf(keyword, "NAXIS%d", &dim_no);
+        if (ret != 1 || dim_no != header->naxis_index + 1) {
+            av_log(avcl, AV_LOG_ERROR, "expected NAXIS%d keyword, found %s = %s\n", header->naxis_index + 1, keyword, value);
+            return AVERROR_INVALIDDATA;
+        }
+
+        if (sscanf(value, "%d", &header->naxisn[header->naxis_index]) != 1) {
+            av_log(avcl, AV_LOG_ERROR, "invalid value of NAXIS%d keyword, %s = %s\n", header->naxis_index + 1, keyword, value);
+            return AVERROR_INVALIDDATA;
+        }
+
+        dict_set_if_not_null(metadata, keyword, value);
+        header->naxis_index++;
+        if (header->naxis_index == header->naxis) {
+            header->state = STATE_REST;
+        }
+        break;
+    case STATE_REST:
+        if (!strcmp(keyword, "BLANK") && sscanf(value, "%"SCNd64"", &t) == 1) {
+            header->blank = t;
+            header->blank_found = 1;
+        } else if (!strcmp(keyword, "BSCALE") && sscanf(value, "%lf", &d) == 1) {
+            header->bscale = d;
+        } else if (!strcmp(keyword, "BZERO") && sscanf(value, "%lf", &d) == 1) {
+            header->bzero = d;
+        } else if (!strcmp(keyword, "CTYPE3") && !strncmp(value, "'RGB", 4)) {
+            header->rgb = 1;
+        } else if (!strcmp(keyword, "DATAMAX") && sscanf(value, "%lf", &d) == 1) {
+            header->data_max_found = 1;
+            header->data_max = d;
+        } else if (!strcmp(keyword, "DATAMIN") && sscanf(value, "%lf", &d) == 1) {
+            header->data_min_found = 1;
+            header->data_min = d;
+        } else if (!strcmp(keyword, "END")) {
+            return 1;
+        } else if (!strcmp(keyword, "GROUPS") && sscanf(value, "%c", &c) == 1) {
+            header->groups = (c == 'T');
+        } else if (!strcmp(keyword, "GCOUNT") && sscanf(value, "%"SCNd64"", &t) == 1) {
+            header->gcount = t;
+        } else if (!strcmp(keyword, "PCOUNT") && sscanf(value, "%"SCNd64"", &t) == 1) {
+            header->pcount = t;
+        }
+        dict_set_if_not_null(metadata, keyword, value);
+        break;
+    }
+    return 0;
+}