Method GetFrame

src/audio_effects/Delay.cpp:61–102

This method is required for all derived classes of EffectBase, and returns a modified openshot::Frame object

// This method is required for all derived classes of EffectBase, and returns a
// modified openshot::Frame object
std::shared_ptr<openshot::Frame> Delay::GetFrame(std::shared_ptr<openshot::Frame> frame, int64_t frame_number)
{
	const float delay_time_value = (float)delay_time.GetValue(frame_number)*(float)frame->SampleRate();
	int local_write_position;

	setup(frame);

	for (int channel = 0; channel < frame->audio->getNumChannels(); channel++)
	{
		float *channel_data = frame->audio->getWritePointer(channel);
		float *delay_data = delay_buffer.getWritePointer(channel);
		local_write_position = delay_write_position;

		for (auto sample = 0; sample < frame->audio->getNumSamples(); ++sample)
		{
			const float in = (float)(channel_data[sample]);
			float out = 0.0f;

			float read_position = fmodf((float)local_write_position - delay_time_value + (float)delay_buffer_samples, delay_buffer_samples);
			int local_read_position = floorf(read_position);

			if (local_read_position != local_write_position)
			{
				float fraction = read_position - (float)local_read_position;
				float delayed1 = delay_data[(local_read_position + 0)];
				float delayed2 = delay_data[(local_read_position + 1) % delay_buffer_samples];
				out = (float)(delayed1 + fraction * (delayed2 - delayed1));

				channel_data[sample] = in + (out - in);
				delay_data[local_write_position] = in;
			}

			if (++local_write_position >= delay_buffer_samples)
				local_write_position -= delay_buffer_samples;
		}
	}

	delay_write_position = local_write_position;

	// return the modified frame
	return frame;
}

// Generate JSON string of this object
std::string Delay::Json() const {