H.265 / HEVC has been promised for many years as the next big CODEC and the successor to H.264. Now with many H.265 IP cameras starting to ship, the market needs to decide on what to use.

In this tutorial, we break down the key issues including:

  • Technical Comparison Between H.264 and H.265
  • Potential Improvements in Quality
  • Limitations in Gains
  • Logistical Barriers in Moving to H.265
  • Motivations to Move to H.265
  • H.265 vs Smart H.264
  • H.265 IPVM Test Results

Overall, the key marketing claims for HEVC/H.265 is reducing bit rate requirements in half to deliver the same quality. For instance, if a 1080p / 30fps H.264 camera required 4Mb/s, the equivalent H.265 camera would be expected to require only 2Mb/s.

For background, see this technical IEEE HEVC/H.265 whitepaper. For the full details, see the current HEVC draft standard document (200+ pages).

Technical Comparison

Three main structural improvements drive H.265’s projected performance gains:

  • Much larger CTUs instead of Macroblocks: While H.264’s maximum block size is 256 pixels (16 x16), H.265’s will be 16x greater at 4096 (64 x 64). Proponents say the larger size enables more efficient encoding, especially for higher resolution images. Read a good technical blog post on CTU details. The video below shows this: