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README.md

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+# SSDV
+
+Simple command line app for encoding / decoding SSDV image data
+
+Created by Philip Heron <[email protected]>  
+http://www.sanslogic.co.uk/ssdv/
+
+A robust packetised version of the `JPEG` image format.
+
+Uses the Reed-Solomon codec written by Phil Karn, KA9Q.
+
+## ENCODING
+
+```shell
+$ ssdv -e -c TEST01 -i ID input.jpeg output.bin
+```
+
+This encodes the `input.jpeg` image file into SSDV packets stored in the `output.bin` file.
+`TEST01` (the callsign, an alphanumeric string up to 6 characters) and `ID` (a number from `0-255`) are encoded into the header of each packet.
+The `ID` should be changed for each new image transmitted to allow the decoder to identify when a new image begins.
+
+The output file contains a series of SSDV packets, each packet always being 256 bytes in length.
+Additional data may be transmitted between each packet, the decoder will ignore this.
+
+## DECODING
+
+```shell
+$ ssdv -d input.bin output.jpeg
+```
+
+This decodes a file `input.bin` containing a series of SSDV packets into the JPEG file `output.jpeg`.
+
+## LIMITATIONS
+
+Only JPEG files are supported, with the following limitations:
+
+ - Greyscale or YUV/YCbCr colour formats
+ - Width and height must be a multiple of 16 (up to a resolution of 4080 x 4080)
+ - Baseline DCT only
+ - The total number of MCU blocks must not exceed 65535
+
+## INSTALLING
+
+```shell
+$ make
+```
+
+## TODO
+
+* Allow the decoder to handle multiple images in the input stream.
+* Experiment with adaptive or multiple huffman tables.