Segment naming policy containing a placeholder of the format '{rand_chars:x}', which will be replaced by a random alphanumeric string of length x (default 32) on each (re)start of the encoding. The resulting string will be copied to the segmentNaming property. Intended to avoid re-use of segment names after restarting a live encoding. If segmentNamingTemplate is set, segmentNaming must not be set.