AJA 12GM 12G-SDI / Quad 3G-SDI Mux/Demux Converter. Model: AJA 12GM. AJA 12GM Main Unit. This is a professional-grade transport converter from AJA Video Systems, essential for 4K/UltraHD workflows. Function: 12G-SDI to/from Quad 3G-SDI Multiplexer/Demultiplexer.