Method MapMaskFrameNumber

src/EffectBase.cpp:357–430

}

int64_t EffectBase::MapMaskFrameNumber(int64_t frame_number) {
	if (!mask_reader)
		return frame_number;

	int64_t requested_index = std::max(int64_t(0), frame_number - 1);
	if (!clip && ParentTimeline()) {
		const double host_fps = ResolveMaskHostFps();
		if (host_fps > 0.0) {
			const int64_t start_offset = static_cast<int64_t>(std::llround(std::max(0.0f, Start()) * host_fps));
			requested_index = std::max(int64_t(0), requested_index - start_offset);
		}
	}
	int64_t mapped_index = requested_index;

	if (mask_time_mode == MASK_TIME_SOURCE_FPS &&
		mask_reader->info.fps.num > 0 && mask_reader->info.fps.den > 0) {
		const double host_fps = ResolveMaskHostFps();
		const double source_fps = mask_reader->info.fps.ToDouble();
		if (host_fps > 0.0 && source_fps > 0.0) {
			const double seconds = static_cast<double>(requested_index) / host_fps;
			mapped_index = static_cast<int64_t>(std::llround(seconds * source_fps));
		}
	}

	const int64_t source_len = mask_reader->info.video_length;
	const double source_fps = (mask_reader->info.fps.num > 0 && mask_reader->info.fps.den > 0)
		? mask_reader->info.fps.ToDouble() : 30.0;
	const double source_duration = ResolveMaskSourceDuration();
	const double start_sec = std::min<double>(std::max(0.0f, Start()), source_duration);
	const double end_sec = std::min<double>(std::max(0.0f, End()), source_duration);

	const int64_t range_start = std::max(int64_t(1), static_cast<int64_t>(std::llround(start_sec * source_fps)) + 1);
	int64_t range_end = (end_sec > 0.0)
		? static_cast<int64_t>(std::llround(end_sec * source_fps)) + 1
		: source_len;
	if (source_len > 0)
		range_end = std::min(range_end, source_len);
	if (range_end < range_start)
		range_end = range_start;

	const int64_t range_len = std::max(int64_t(1), range_end - range_start + 1);
	int64_t range_index = mapped_index;

	switch (mask_loop_mode) {
	case MASK_LOOP_REPEAT:
		range_index = mapped_index % range_len;
		break;
	case MASK_LOOP_PING_PONG:
		if (range_len > 1) {
			const int64_t cycle_len = (range_len * 2) - 2;
			int64_t phase = mapped_index % cycle_len;
			if (phase >= range_len)
				phase = cycle_len - phase;
			range_index = phase;
		} else {
			range_index = 0;
		}
		break;