Access to Livestream Studio is included with Vimeo Premium and Vimeo Enterprise membership. With Livestream Studio, you can use H.265 (High-efficiency Video Compression, or HEVC) video compression, allowing you to send your stream using less bandwidth than the older standard H.264 compression requires. Studio is currently the only encoder that can use H.265 to stream to Vimeo.
Difference between H.264 and H.265
The biggest difference between H.264 and H.265 is mainly the size or bitrate requirement to process a certain quality of video. H.265 is more efficient and thus can produce the same quality stream as H.264 using half the bitrate.
For example, if you want to send out a 1080p stream, that would typically average a bitrate of about 4-5Mbps if you use H.264 video compression, whereas the same 1080p stream can be sent at 2-3Mbps if you use H.265.
Requirement: Hardware encoding
The quickest way to know if you have it is to launch Livestream Studio, navigate to the settings menu (the gearwheel in the upper right corner).
Select the Streaming menu. If you see the checkbox labeled Hardware encoding, then your system is good to go. Make sure this is checked if you want to use H.265, and be sure to click Save.
Enable H.265 in Studio
Once you've enabled hardware encoding, navigate to the STREAM tab in Studio and select Vimeo as your provider. Set up your stream as usual, but before going live, click the gearwheel next to the quality dropdown menu to see more advanced options for your stream.
Under Video compression format, select H.265 (HEVC). Notice the bitrate amount next to your chosen quality will be reduced by half.
Note that this feature in Studio is only available for Vimeo; other providers Studio can stream to will be disabled if you select this compression.
Once you're ready, you can go live to Vimeo.