Rewrite Audio output

Created by: Silas Della Contrada

When playing a video with an audio track, audio starts crackling after ca. 10 seconds. Because of the new video renderer timing, the audio also starts lagging behind the video after some pause/resume-events.

The audio output has to be rewritten completely to support VFR video.

To-dos

• Add frameProcessingStarted(qint64 pts, qint64 duration) and frameProcessingFinished(qint64 pts, qint64 duration) signals to IFrameSink to be able to sync with it.
• Rewrite audio output to sync via the frameProcessingStarted() signal
• Test with pause/resume

Important

• These signals are not allowed to be triggered more than once, when having to present this frame repeatedly
• After these changes, frame sinks should only process a frame, if there is at least one future frame in its queue to calculate the duration of the frame