Most Annoying Issue in Filming, SOLVED! feat. @KOUMAN

Quick Overview

The video demonstrates how to fix flickering LED lights by using a PWM (Pulse Width Modulation) controller with an RC filter to smooth the voltage, as opposed to simply adjusting the DC voltage, which causes issues with different colored LEDs and can lead to flickering due to aliasing between the LED's switching frequency and the camera's frame rate.

Key Points: The core problem addressed is flickering LED lights in a "Kouman" sign due to the mismatch between the LED's switching frequency and the camera's frame rate, causing aliasing artifacts. Directly adjusting the DC voltage to dim LEDs is shown to be ineffective and can lead to uneven brightness and color issues across different colored LEDs. The solution involves using a PWM (Pulse Width Modulation) controller to turn the LEDs on and off rapidly at a high frequency (around 140 kHz, far above the camera's frame rate). An RC filter is added to smooth the PWM signal into a more stable DC voltage, ensuring consistent brightness and eliminating flickering. The video demonstrates the difference in output signals on an oscilloscope: a raw PWM signal versus a smoothed DC signal after passing through the RC filter. The presenters, Kouman, Iman, and Bahram, humorously attempt to troubleshoot the flickering LEDs by adjusting the PWM duty cycle and eventually implementing the RC filter solution. The final setup successfully dims the LEDs without flicker, as observed on the oscilloscope and visually.

Context: The video features the YouTube channel "Kouman" where hosts Kouman and Iman, along with a guest (implied to be Bahram), encounter an issue with flickering LED lights in their studio setup. The problem is identified as a common issue in filming LED lights, particularly when the camera's shutter speed and the LED's switching frequency are not synchronized. The video aims to explain the technical reason behind this flickering and demonstrate a solution using electronics principles.

Detailed Analysis

The video addresses the common problem of flickering LED lights when filmed, which occurs due to the interaction between the camera's frame rate/shutter speed and the LED's switching frequency. The hosts Kouman and Iman, along with Bahram, demonstrate this issue using a "Kouman" sign with multiple colored LEDs. They explain that simply adjusting the DC voltage to dim the LEDs is not ideal, as it can lead to uneven brightness and color issues. The primary cause of flickering in videos is identified as aliasing, where the sampling rate of the camera (determined by frame rate and shutter speed) is too slow relative to the LED's switching frequency. To solve this, they propose using a PWM (Pulse Width Modulation) controller to switch the LEDs on and off at a very high frequency (around 140 kHz). This rapid switching, when its frequency is much higher than the camera's sampling rate, appears as a steady, dimmed light to the human eye due to persistence of vision. However, the raw PWM signal still exhibits variations that the camera captures as flickering. The ultimate solution demonstrated is to add an RC (Resistor-Capacitor) filter to the PWM output. This filter smooths the pulsed signal into a more stable DC voltage, effectively eliminating the flickering when viewed through the camera. They measure the voltage and observe the wave patterns on an oscilloscope to confirm the effectiveness of the RC filter in providing a steady DC output, thus solving the filming issue.