• Classroom-wide Audio Recording

The primary method for recording audio throughout the entire classroom is by installing microphones on the desks, capturing the voices of both teachers and students. However, this method results in excessively noisy audio in course videos.

Later, system providers addressed this issue by integrating a conference system audio recording method into the course recording system. An additional confirmation button was added to the microphone, and audio recording is only activated when the confirmation button is pressed, resolving the issue of background noise. However, this approach may lead to damage to the recording microphones, adding a burden to school maintenance.

• Teacher Wireless Microphone Recording

Due to the extensive promotion by [磨課師], many manufacturers are contemplating how to strengthen course recording. In the last segment, we specifically introduced the video recording system, incorporating broadcast filming techniques to enhance the quality of course recordings. By utilizing technology and comprehensive system operations, the standard of course videos is elevated, consequently increasing students' willingness to watch courses online. In this segment, we also observe the audio systems, noting that some manufacturers have incorporated the concept of broadcasting into their designs. Below, we provide a detailed analysis.

Broadcast audio recording naturally requires mixing equipment. Audio control personnel switch to the appropriate audio output based on real-time sound needs. This is combined with the video output from broadcasting equipment for simultaneous recording. Three key points must be considered:

1. Area A video must be accompanied by Area A audio.

The classroom is divided into different audio recording zones, corresponding to the positions captured by cameras. When the system automatically switches the camera to capture Area A video, it simultaneously adjusts the audio system to only capture audio from Area A. Sounds from other areas are not recorded in the video, resulting in clear video and audio.

2. Audio must have delayed output for synchronized speech.

Typically, video processing is slower, leading to audio-video asynchrony. Recorded videos must undergo post-processing to synchronize the audio. This system introduces the concept of delayed broadcast audio, where the audio passes through a delay device before reaching the recording system. Thus, after the initial processing, the course video's audio is already synchronized, eliminating the need for additional time-consuming post-processing.

3. Audio devices are placed in locations inaccessible to students.

All audio devices are installed in a matrix pattern on the ceiling, with all wiring configured above the ceiling. This ensures that audio devices are protected from accidental damage, providing cost savings for the school.

This is the practical experience of the author with the audio system, similar to a broadcasting setup in a large studio. When camera 1 captures video, the overall audio is transformed into the video and audio of camera 1, without interference from sounds in other positions. This is the true essence of a broadcast-style course recording system.

Over the past two segments reporting on [磨課師]'s course recording project, the main goal is to make everyone aware that, under technological operation, using broadcast concepts to record course videos is a trend. The reason lies in the increasing quality of online video playback. If course videos continue to follow traditional surveillance recording methods and are placed online for student viewing, the author believes that the likelihood of students wanting to watch is not high. Hence, we have provided new ideas for course recording in two consecutive issues, encouraging schools and system providers to reconsider how the next lesson should be filmed.