If its another file, it will be in NOAA Specifc header. If its an image, we will have the compression flag set on Image Structure Header. In headers of type 1 (Image Structure Header) or type 129 (NOAA Specific Header) both describe if its compressed or not. getHeaderData ( data ) for i in p : if i = 1 or i = 129 : isCompressed = not i = 0 if i = 1 : pixels = i If packet = 1 : print "Starting packet %s_%s_%s.lrit" % ( packet, packet, packet ) startnum = packet p = packetmanager. In our savePacket function, if the packet is a start packet, we should run the getHeaderData from packetmanager and check the compression flags. Text files and DCS files are usually not compressed. If they just need to be appended, we only do that. So in our channeldecoder.py we need to do few steps.įirst let’s check if either the packet stream will need to be decompressed or just appended. The Multi File Decompression will look into StartNumber-1 to EndNumber files, being the StartNumber-1 just rewrited to the output file that will have a _decomp suffix. The StartNumber should be the number of the first continuation packet (so not the header packet). So the output file will be a single file with all of the original files together (so our final LRIT file). It does basically the same as single file, but iterates over several files and decompress all of them into a single file. We’re gonna use the Multi File decompression. Multi File Decompression: decompressor.exe Prefix StartNumber EndNumber.Single File Decompression: decompressor.exe Pixels Filename.The decompressor is made to receive some arguments and has two ways of operation: But for those who want, just open the visual studio solution and hit compile, it should generate a decompressor.exe that we will be using together with wine and python (or if you’re at windows, just with python). The project of decompressor is available here:, I will soon release some binaries for those who don’t want to compile the application themselves. Make a windows application to decompress and run through wine. Since the LritRice from linux is “broken”, I made a very nasty workaround: With time I will reverse engineer and create a open version that will be able to decompress LRIT data, but for now I had to do a workaround. Although RICE compression is a open standard (NASA’s fitsio library has compression and decompression of RICE), the LritRice use a modified version. No recent updates have been made to the tool, though.Usually for images, the data is compressed using LritRice.lib. We have not found any problems in our testing.Īlthough it is not the most resourceful application available, GUnzip offers a straightforward and free solution to extracting GZIP files rapidly and with minimum effort. It is very responsive to commands and works well, without causing the OS to hang, crash or show error notifications. GUnzip does not put a strain on computer performance because it runs on a low-to-moderate quantity of CPU and RAM. All you have to do is establish the output directory and proceed with the extraction operation. The interface is represented by a very small window where you can click a button to point out to a GZIP archive for processing, as the drag-and-drop feature is not supported. What's worth mentioning is that no new entries are added to the Windows registry, and extra files are not created on the hard disk without the user's consent. You can drop the JNLP file anywhere on the hard disk and click it to run.Īn alternative is to save GUnzip to a USB flash disk or similar storage unit, in order to run it on any computer with Java seamlessly. Installation is not a requirement, but you must have Java installed on your computer. It is very simple to use, since there are no configuration settings put at your disposal. GUnzip is Java-based application whose only purpose is to extract archives compressed with the GZIP format, as the name implies.
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