Method apply_timemapping

src/Clip.cpp:573–723

Adjust the audio and image of a time mapped frame

// Adjust the audio and image of a time mapped frame
void Clip::apply_timemapping(std::shared_ptr<Frame> frame)
{
	// Check for valid reader
	if (!reader)
		// Throw error if reader not initialized
		throw ReaderClosed("No Reader has been initialized for this Clip.  Call Reader(*reader) before calling this method.");

	// Check for a valid time map curve
	if (time.GetLength() > 1)
	{
		const std::lock_guard<std::recursive_mutex> lock(getFrameMutex);

		int64_t clip_frame_number = frame->number;
		int64_t new_frame_number = adjust_frame_number_minimum(time.GetLong(clip_frame_number));

		// create buffer
		juce::AudioBuffer<float> *source_samples = nullptr;

		// Get delta (difference from this frame to the next time mapped frame: Y value)
		double delta = time.GetDelta(clip_frame_number + 1);
		const bool prev_is_increasing = time.IsIncreasing(clip_frame_number);
		const bool is_increasing = time.IsIncreasing(clip_frame_number + 1);

		// Determine length of source audio (in samples)
		// A delta of 1.0 == normal expected samples
		// A delta of 0.5 == 50% of normal expected samples
		// A delta of 2.0 == 200% of normal expected samples
		int target_sample_count = Frame::GetSamplesPerFrame(adjust_timeline_framenumber(clip_frame_number), Reader()->info.fps,
															  Reader()->info.sample_rate,
															  Reader()->info.channels);
		int source_sample_count = round(target_sample_count * fabs(delta));

		// Determine starting audio location
		AudioLocation location;
		if (previous_location.frame == 0 || abs(new_frame_number - previous_location.frame) > 2 || prev_is_increasing != is_increasing) {
			// No previous location OR gap detected
			location.frame = new_frame_number;
			location.sample_start = 0;

			// Create / Reset resampler
			// We don't want to interpolate between unrelated audio data
			if (resampler) {
				delete resampler;
				resampler = nullptr;
			}
			// Init resampler with # channels from Reader (should match the timeline)
			resampler = new AudioResampler(Reader()->info.channels);

			// Allocate buffer of silence to initialize some data inside the resampler
			// To prevent it from becoming input limited
			juce::AudioBuffer<float> init_samples(Reader()->info.channels, 64);
			init_samples.clear();
			resampler->SetBuffer(&init_samples, 1.0);
			resampler->GetResampledBuffer();

		} else {
			// Use previous location
			location = previous_location;