Method adjust_timeline_framenumber

src/Clip.cpp:1619–1639

Adjust frame number for Clip position and start (which can result in a different number)

// Adjust frame number for Clip position and start (which can result in a different number)
int64_t Clip::adjust_timeline_framenumber(int64_t clip_frame_number) {

	// Get clip position from parent clip (if any)
	float position = 0.0;
	float start = 0.0;
	Clip *parent = static_cast<Clip *>(ParentClip());
	if (parent) {
		position = parent->Position();
		start = parent->Start();
	}

	// Adjust start frame and position based on parent clip.
	// This ensures the same frame # is used by mapped readers and clips,
	// when calculating samples per frame.
	// Thus, this prevents gaps and mismatches in # of samples.
	int64_t clip_start_frame = (start * info.fps.ToDouble()) + 1;
	int64_t clip_start_position = round(position * info.fps.ToDouble()) + 1;
	int64_t frame_number = clip_frame_number + clip_start_position - clip_start_frame;

	return frame_number;
}