High-Efficiency Video Coding (HEVC) can offer storage savings of 50% to 75% at the same video quality against standard AVC/H264 video coding.
FFmpeg http://ffmpeg.org software can be used to convert H264 video to HEVC.
Video conversion may be executed by a hardware graphics card or by PC software.
NVIDIA Graphics card example
c:\ffmpeg\bin\ffmpeg -hwaccel cuda -hwaccel_output_format cuda -i c:\ffmpeg\Video_h264.ts -c:v hevc_nvenc -preset slow -c:a aac -ac 2 -b:a 256k c:\ffmpeg\Video_hevc.ts
PC Software example
c:\ffmpeg\bin\ffmpeg -i c:\ffmpeg\Video_h264.ts -c:v libx265 -preset medium -x265-params crf=28 -c:a aac -ac 2 -b:a 256k -strict experimental c:\ffmpeg\Video_hevc.ts