When configuring an event-based recording using a pre-buffer there are some restrictions on the use of certain Zipstream features. The reason is that for each pre-buffer the recorder needs to keep up to two entire GOP (Group of Pictures) segments in RAM. There is no exact upper limit since it depends on the bitrate, but it is recommended to not exceed 100 frames per GOP. The Zipstream parameters that are restricted are given by the following table with corresponding valid values:
|Stream option||Valid values|
It is possible to use GOP and FPS (Frames Per Second) mode simultaneously. The following is for example a valid combination videozgopmode=fixed&videokeyframeinterval=100&videozfpsmode=dynamic&videoframeskipmode=empty
The VMS should always set these stream options when configuring a recording rule using a pre-buffer.