Converting videos from higher resolutions to lower ones is a common practice, especially when creating compact versions for web sharing or streaming. Using the ffmpeg tool available for the CentOS 7 operating system, you can easily accomplish this task. Here's the command to convert a 4K video to a 1080p trailer, reduce the bitrate, and save it in MP4 format:

ffmpeg -i input_video.mp4 -vf "scale=-1:1080,format=yuv420p" -b:v 5M -c:a copy output_video.mp4

How does this command work?

• -i input_video.mp4: This parameter specifies the input video file.
• -vf "scale=-1:1080,format=yuv420p": This parameter resizes the video to 1080p resolution. The yuv420p format is preferred for web videos.
• -b:v 5M: This parameter sets the video bitrate to 5 Mbps. You can adjust this parameter according to your needs.
• -c:a copy: This parameter ensures that the audio track will be preserved in its original format, speeding up the process and maintaining audio quality.
• output_video.mp4: This parameter specifies the output name and format of the video.

This way, you can easily use the ffmpeg command on the CentOS 7 operating system to convert a 4K video to a 1080p trailer, reduce the bitrate, and save it in MP4 format. This process allows you to efficiently manage file sizes while preserving video quality for online sharing and streaming.