So here it is and its open source (Apache License, Version 2.0):
Patches are welcome :)
It decodes the following modes at the moment:
Robot Modes: 36 & 72
PD Modes: 50, 90, 120, 160, 180, 240 & 290
Martin Modes: 1 & 2
Scottie Modes: 1, 2 & DX
Wraase Modes: SC2 180
You can even watch old B/W or unsupported modes in the "Raw Mode".
If an calibration header gets detected, the resulting image will be saved in the "Pictures" directory and can be immediately seen in the Image gallery.
Switching away to another application will not stop the decoder and will continue to run in background.
To stop the decoder, you must exit via the "back" button of Android.
Here you can find my wife's free open source SSTV Encoder:
You're welcome to join our "Robot36 SSTV Alpha Testers" community on Google+ to help test alpha releases:
Here a schematic for a line or headphone output to microphone input converter:
There are still some things that need to be addressed but for now: please enjoy testing :)