For Reducing video quality using FFmpeg

FFmpeg is required to run the project FFmpeg download website for windows
Direct Download link use 7-Zip for extraction. ffmpeg.exe will be inside bin folder, copy it to ReduceVideoQuality.ps1 location

1. Download ReduceVideoQuality.ps1 file from github
   • OR Download Repository as Zip and Extract
   • OR git clone https://github.com/ankitT20/FFmpeg_whatsapp.git
2. Ensure ffmpeg.exe is in the same directory/folder as the ReduceVideoQuality.ps1 and video file.
3. Select and Right click ReduceVideoQuality.ps1, click Run with PowerShell.
   • OR Open PowerShell, navigate to the directory containing the script, and run it using ReduceVideoQuality.ps1.
4. Follow the prompts to provide the filename and select options.

If running scripts is dissabled on your system, search powershell, Right click and 'Run as Administrator', and run the following: Set-ExecutionPolicy -ExecutionPolicy RemoteSigned

ffmpeg -i input.mp4 -vcodec libx265 -crf 28 output.mp4
ffmpeg -i input.mp4 -vcodec libx265 -crf 23 output.mp4
ffmpeg -i input.mp4 -c:v libx265 -crf 26 -preset fast -c:a aac -b:a 128k output.mp4

default crf value is 23, and libx265 is HEVC (High Efficiency Video Coding) , for x264 refer

ffmpeg -i input.mp4 -vcodec libx265 -x265-params lossless=1 output.mp4

verify using console output - x265 [info]: Rate Control : Lossless

calculate bitrate

64 * 8000 / 349 = 1467

64(desired file size) * 8(byte to bit) * 1000(MB to KB) / 349(duration of video in seconds) = 1467 (do multiplication first)

ffmpeg -y -i input.mp4 -c:v libx265 -b:v 1467k -x265-params pass=1 -an -f null NUL && ^
ffmpeg -i input.mp4 -c:v libx265 -b:v 1467k -x265-params pass=2 -an output_64MB.mp4

calculate bitrate

64 * 8000 / 349 = 1467

64(desired file size) * 8(byte to bit) * 1000(MB to KB) / 349(duration of video in seconds) = 1467 (do multiplication first)

1467 - 128 kBit/s (desired audio bitrate) = 1339 kBit/s video bitrate

ffmpeg -y -i input.mp4 -c:v libx265 -b:v 1339k -x265-params pass=1 -an -f null NUL && ^
ffmpeg -i input.mp4 -c:v libx265 -b:v 1339k -x265-params pass=2 -c:a aac -b:a 128k output.mp4

Refrence