1067754 - Introduce type-safety around various media clocks

Status: NEW

(Core :: Audio/Video: Playback, defect)

Description

[Matthew Gregan [:kinetik]]

Spinning this off from bug 1065715 since it's sufficiently different to be worthy of its own bug:

We've had a number of bugs in the past, either in release or during development, that would be avoidable with some type safety introduced to the various media clocks.

These issues arise from inadvertent mixing timeline calculations between start-time based and zero-based timelines.  At present, the clocks are represented as a set of bare int64_ts (a start time, a current time, perhaps an end time), and because the naming and types of these bare integers can be similar and confusion, it's easy to introduce bugs into the various media clock calculations.