mpegtsmux: performance issue

Submitted by Edward Hervey `@bilboed`

Created attachment 256917
callgrind graph of mpegtsmux usage

mpegtsmux does a lot of allocation, mapping and adapter usage.

Ideally it should introduce very little overhead (it doesn't even need to read the input data, just mux it).

right now it uses ~80000 cpu instructions per incoming buffer.

Attachment 256917, "callgrind graph of mpegtsmux usage":