what type of HDMI cable to use?

Hi,

HDMI connector is international standard, any HDMI cable could connect your MacBook Pro.

MacBook Pro (Retina, 15-inch, Mid 2014) - Technical Specifications

MacBook Pro (Retina, 13-inch, Mid 2014) - Technical Specifications

No.

Macs have always used full size HDMI cables, and the 2014 model has standard HDMI ports.

can you post a picture of the ends of this cable?

or see if an end matches something else on this chart:

HDMI cables you want for HDMI-only Displays (higher resolutions than 720p TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:

"Premium High Speed HDMI cable" or that + "with Ethernet" --OR--

"Ultra High Speed HDMI cable" or that + "48G"

Cables with No Certification tags are good for your standard 720p TV set, and not much more.