I'm taking an HDMI signal and sending it out on a stream via Cerevo LiveShell Pro. I need to take that same signal, probably split it, and record a copy of the stream. Someone said a Atomos Ninja was the way to go.. anyone argue this? Have an affordable alternative to suggest???

Ninja 2 has HDMI pass-thru, so camera HDMI output goes into Ninja 2, gets recorded as ProRes, HDMI is passed on to Cerevo for live streaming.

Another option is a Matrox Monarch HD - this single unit records AND streams. Records as H.264 to USB device or SD card. HDMI input with pass-thru (to monitor for example).

Thanks

Forgive my ignorance.. what is "ProRes"? Is that an Apple thing?

ProRes is a family of digital intermediate CODECS (similar to AVID's DNxHD) that are Intra frame compressed to allow exceptional quality and editing responsiveness at a given bitrate, introduced by Apple. It has been widely adopted as an acquisition format despite poor implementation on the PC side of things.