Short answer: H.265 (also called HEVC) usually needs 30–50% less bitrate than H.264 for a similar picture, which means less storage and less network traffic. The cost is more processing to play it back, and some browsers and older software can’t play it at all. Use H.265 for recording when your VMS and viewing devices handle it.
What is a video codec?
A codec is the method a camera uses to compress video before sending it. Uncompressed 1080p video runs to hundreds of megabits per second; a codec shrinks it to a few megabits by storing what changes between frames rather than every pixel of every frame. H.264 (AVC) has been the standard since the mid-2000s. H.265 (HEVC) is its successor.
Why is H.265 smaller?
H.265 looks at the picture in more flexible blocks, up to 64×64 pixels where H.264 uses 16×16, and has more ways to predict what a block will look like from its neighbours and from earlier frames. Large flat areas such as walls, floors and sky cost far fewer bits, which suits security footage, where most of the frame doesn’t move.
What does that save?
| H.264 | H.265 | |
|---|---|---|
| 4 MP camera, typical bitrate | about 6 Mbps | about 3 Mbps |
| Storage per camera per day | about 65 GB | about 32 GB |
| 16 cameras, 30 days | about 31 TB | about 16 TB |
Real numbers vary with the scene. Use the storage calculator with your own bitrates.
What’s the catch?
- Playback takes more work. Decoding H.265 costs more processing. Grids of many cameras are where this shows; substreams help.
- Not everything can play it. Browser support for H.265 varies by browser, operating system and graphics hardware, so web viewers often convert it first.
- Older software and recorders may not accept H.265 at all.
What about “smart” codecs?
Many makers add a layer on top of H.264 or H.265 that lowers bitrate further when the scene is still, such as Axis Zipstream and Hanwha WiseStream. They’re worth turning on; the stream stays standard, so any VMS can play it.
Do ONVIF cameras support H.265?
ONVIF Profile T, the profile to look for on new cameras, includes H.265. Older Profile S cameras may only offer H.264 over ONVIF. See What is ONVIF?
How Supervision handles it
When a viewing device can’t play a camera’s stream directly, the Supervision server converts it, using the GPU when there is one and only for the cameras that need it.
Common questions
Will switching to H.265 lower quality?
At the same bitrate, H.265 looks better; at half the bitrate, it looks about the same. Change one camera, compare a day of footage, then roll it out.
Can I mix H.264 and H.265 cameras?
Yes, as long as your VMS handles both. Most current ones do.
What about AV1 or H.266?
Few security cameras offer them yet. H.265 is the practical choice today.
Supervision is self-hosted video management software for any camera brand. If this is the kind of problem you're solving, tell us about your cameras and we'll talk it through, or email hello@bipolarfactory.com.