These units up convert Composite or S video to HDMI . Analogue Audio into the unit is embedded in the HDMI out MV-304  has Composite, S video and RCA inputs and an HDMI output.  (  and a 3,5mm Audio output jack )

It can therefore embed Analogue audio in the HDMI out, but also gives analogue audio out . Metal housing MV-305  has Composite, S video and RCA inputs  and an  HDMI output (as well as an HDMI input) It can therefore also convert HDMI to HDMI. Plastic housing

Both supplied with 5 V power supply

When the need arises it is sometimes required to upscale an analogue signal to be able to output it via HDMI.

On MV-304 HDMI output spec is 720P/ 60HZ or 1080P/ 60HZ

On MV-305 the HDMI input supports:
480i@60Hz ,  480P@60Hz ,   576i @50Hz,  576P@ 50Hz,  720P@ 50/60 Hz,  1080i @ 50/ 60 Hz,  1080P @ 50/60 Hz

On MV-305 the HDMI output spec is 720P/ 50/60HZ or 1080P/ 50/60HZ