HDMI to BNC video converter is an adapter for full HDMI equipment sources which are from TV box , game console ( PS3 / PS4 / XBOX One 360 ), ordinary cameras , Blue-ray DVD Player or high-definition player etc. transforming into BNC CVBS output or converting the audio and video signals of NTSC / PAL format to 480P / 576I analog signals which are used on normal old TV / Monitor / VCR / DVR / VHS etc.devices . It widly applicate to KTV equipment or meeting / presentation that converts full HD camera signals to the video recording capture card of computer for remote control( HTTP ) or web conferencing meeting Will this convert the hdmi input from a roku device and convert and output to bnc (coax)? Yes, this hdmi in coaxial bnc out adapter will convert the hdmi input from a roku device and convert output to bnc ( coaxial ) , but please note that the audio output of roku device is by 3.5 mm stereo（L/R）output on this converter . Confirm the source device is BNC CVBS analog signal with coax connector port , NOT the coax RF / antenna connector port and AHD / TVI / CVI analog signal or SDI digital signal , Please don't use it for AHD to HDMI , TVI to HDMI , CVI to HDMI or SDI to HDMI; Check all the cables by direct connect with source and display.Check the power supply to see if it has electricity or the light is lihgting. Specs: Input: HDMI / MHL Output: BNC & 3.5 mm stereo（L/R） Support Input Video Format: PAL / NTSC HDMI Input Resolution： 480P,576P,720P,1080I,800x600,1024x768,1280x720,1280x1024,1080P@60Hz Compatible with HDMI1.3 ,support HDCP 2.0 BNC Output Resolution： 480P or 576I（optional） Picture Output Resolution： 4:3 or 16:9（optional） Power: USB Packages 1x HDMI to BNC Converter 1x Power Adapter