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/*
* FITS muxer
* 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 muxer.
*/
#include "internal.h"
typedef struct FITSContext {
int first_image;
} FITSContext;
static int fits_write_header(AVFormatContext *s)
{
FITSContext *fitsctx = s->priv_data;
fitsctx->first_image = 1;
return 0;
}
/**
* Write one header line comprising of keyword and value(int)
* @param s AVFormat Context
* @param keyword pointer to the char array in which keyword is stored
* @param value the value corresponding to the keyword
* @param lines_written to keep track of lines written so far
* @return 0
*/
static int write_keyword_value(AVFormatContext *s, const char *keyword, int value, int *lines_written)
{
int len, ret;
uint8_t header[80];
len = strlen(keyword);
memset(header, ' ', sizeof(header));
memcpy(header, keyword, len);
header[8] = '=';
header[9] = ' ';
ret = snprintf(header + 10, 70, "%d", value);
header[ret + 10] = ' ';
avio_write(s->pb, header, sizeof(header));
*lines_written += 1;
return 0;
}
static int write_image_header(AVFormatContext *s)
{
AVStream *st = s->streams[0];
AVCodecParameters *encctx = st->codecpar;
FITSContext *fitsctx = s->priv_data;
uint8_t buffer[80];
int bitpix, naxis, naxis3 = 1, bzero = 0, rgb = 0, lines_written = 0, lines_left;
switch (encctx->format) {
case AV_PIX_FMT_GRAY8:
bitpix = 8;
naxis = 2;
break;
case AV_PIX_FMT_GRAY16BE:
bitpix = 16;
naxis = 2;
bzero = 32768;
break;
case AV_PIX_FMT_GBRP:
case AV_PIX_FMT_GBRAP:
bitpix = 8;
naxis = 3;
rgb = 1;
if (encctx->format == AV_PIX_FMT_GBRP) {
naxis3 = 3;
} else {
naxis3 = 4;
}
break;
case AV_PIX_FMT_GBRP16BE:
case AV_PIX_FMT_GBRAP16BE:
bitpix = 16;
naxis = 3;
rgb = 1;
if (encctx->format == AV_PIX_FMT_GBRP16BE) {
naxis3 = 3;
} else {
naxis3 = 4;
}
bzero = 32768;
break;
}
if (fitsctx->first_image) {
memcpy(buffer, "SIMPLE = ", 10);
memset(buffer + 10, ' ', 70);
buffer[29] = 'T';
avio_write(s->pb, buffer, sizeof(buffer));
} else {
memcpy(buffer, "XTENSION= 'IMAGE '", 20);
memset(buffer + 20, ' ', 60);
avio_write(s->pb, buffer, sizeof(buffer));
}
lines_written++;
write_keyword_value(s, "BITPIX", bitpix, &lines_written); // no of bits per pixel
write_keyword_value(s, "NAXIS", naxis, &lines_written); // no of dimensions of image
write_keyword_value(s, "NAXIS1", encctx->width, &lines_written); // first dimension i.e. width
write_keyword_value(s, "NAXIS2", encctx->height, &lines_written); // second dimension i.e. height
if (rgb)
write_keyword_value(s, "NAXIS3", naxis3, &lines_written); // third dimension to store RGBA planes
if (!fitsctx->first_image) {
write_keyword_value(s, "PCOUNT", 0, &lines_written);
write_keyword_value(s, "GCOUNT", 1, &lines_written);
} else {
fitsctx->first_image = 0;
}
/*
* Since FITS does not support unsigned 16 bit integers,
* BZERO = 32768 is used to store unsigned 16 bit integers as
* signed integers so that it can be read properly.
*/
if (bitpix == 16)
write_keyword_value(s, "BZERO", bzero, &lines_written);
if (rgb) {
memcpy(buffer, "CTYPE3 = 'RGB '", 20);
memset(buffer + 20, ' ', 60);
avio_write(s->pb, buffer, sizeof(buffer));
lines_written++;
}
memcpy(buffer, "END", 3);
memset(buffer + 3, ' ', 77);
avio_write(s->pb, buffer, sizeof(buffer));
lines_written++;
lines_left = ((lines_written + 35) / 36) * 36 - lines_written;
memset(buffer, ' ', 80);
while (lines_left > 0) {
avio_write(s->pb, buffer, sizeof(buffer));
lines_left--;
}
return 0;
}
static int fits_write_packet(AVFormatContext *s, AVPacket *pkt)
{
write_image_header(s);
avio_write(s->pb, pkt->data, pkt->size);
return 0;
}
AVOutputFormat ff_fits_muxer = {
.name = "fits",
.long_name = NULL_IF_CONFIG_SMALL("Flexible Image Transport System"),
.extensions = "fits",
.priv_data_size = sizeof(FITSContext),
.audio_codec = AV_CODEC_ID_NONE,
.video_codec = AV_CODEC_ID_FITS,
.write_header = fits_write_header,
.write_packet = fits_write_packet,
};
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