H.264, also called AVC (Advanced Video Coding), is the video compression standard that has carried most of the world's surveillance video for over a decade. Standardised jointly by ITU-T and ISO/IEC, it shrinks raw camera frames enough to stream and store at practical bitrates while keeping wide hardware support: virtually every camera, VMS, browser, and phone can decode it, which is exactly why it became the safe default.
It works by sending occasional full "keyframes" (I-frames) and, in between, much smaller frames that describe only what changed — so a static corridor compresses far harder than a busy street. For surveillance this matters because the bitrate, and therefore the storage bill, depends heavily on scene motion, resolution, and frame rate. A 1080p camera on H.264 commonly lands around 4–8 Mbps.
The trade-off against its successor H.265 is efficiency. H.265 delivers similar quality at roughly half the bitrate, which is decisive at 4K or across hundreds of cameras, but H.264 still wins on universal compatibility and licence simplicity. The pitfall is defaulting to H.264 on a large 4K deployment out of habit: the extra storage and bandwidth can dwarf the convenience. For the codec choice in depth, this is owned by the Video Encoding section, not the VMS layer.
