In our Video Over IP post, we touched on the encoding and decoding process that makes it possible to send video signals over the network. Now let’s take a brief overview of the codecs — which are encoding and decoding protocols — that employ these processes.
Codecs that use about 10Mbps (megabits per second) are ideal for transporting networked AV since they won’t allow the signals to monopolize your network. Conversely, a 10Gbps (gigabits per second) codec will use up all the available bandwidth on a 10-gigabit network link. On the plus side, the latency — the delay caused by the process of encoding and decoding a video signal — will be low for this bandwidth-heavy codec.
Mezzanine, Intra-frame, and Inter-frame
Mezzanine, intra-frame, and inter-frame codecs will look at the source signal in different ways before compressing it for transmission. You want to have the most bandwidth-efficient codecs handling your signals. Even though there will be a trade-off in latency, that trade-off can be acceptable.
- Mezzanine: These include TICO and DSC compression codecs. Latency is very low, but they also use the most bandwidth.
- Intra-frame: These are JPEG2000 and VC-2 codecs. More efficient than Mezzanine in terms of bandwidth, but unable to stream to laptops and mobile devices.
- Inter-frame: H.264 and H.265. H.264 AVC is the most common codec in use today. H.265 HEVC is the next generation. Latency will be about 200ms in the best case, which is considered acceptable.
Crestron’s “State of Networked Video and Integrated System Design” offers an easy-to-understand overview of these codec types, and the areas you need to address to have an integrated system of video distribution and devices — including network management, control, and security.