How to fix a lecture video's crappy audio

Teachers don't know how to use basic audio devices, like microphones. You need some tools to help you with hearing. So ffmpeg is here to help!

Kalle Tolonen
March 7, 2025

For this, you'll need to install ffmpeg from Linux cli:

sudo apt-get update
sudo apt-get install ffmpeg

After that, you can run the noise removal & volume boost:

ffmpeg -i input.mp4 -vf "hqdn3d" -af "volume=6" output.mp4

This will 6x the volume and

-vf "hqdn3d": Applies the high-quality denoise filter to the video.

applies a high quality noise filter to the video.

Output should look something like this:

  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.76.100
  Stream #0:0(unk): Video: h264 (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 30 fps, 15360 tbn (default)
    Metadata:
      handler_name    : ISO Video Handler
      vendor_id       : [0][0][0][0]
      encoder         : Lavc58.134.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
  Stream #0:1(unk): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      handler_name    : ISO Audio Handler
      vendor_id       : [0][0][0][0]
      encoder         : Lavc58.134.100 aac
frame=138045 fps= 92 q=29.0 size=  154368kB time=01:16:41.65 bitrate= 274.8kbits/s dup=0 drop=5 speed=3.05x