nnog / denoise

Denoise the background audio in a video file using ffmpeg, sox and libvo_aacenc to re-encode as 128k AAC.

denoise

Denoise the background audio in a video file using ffmpeg, sox and libvo_aacenc to re-encode as single-channel 128k AAC.

This took me an annoyingly long time to work out how to do; hence githubbing it.

This was intended to scratch a personal itch (a very noisy itch) so open it up and edit the values before using.

Producing MP4/H.264 video with 1-channel 128k AAC headset mic-recorded screencast (I recommend SimpleScreenRecorder on linux) yielded background audio noise that this script sorts out.

To run in batch on mp4 files:

$ find . -name \*.mp4 -exec ./denoise.sh {} \;

denoise's Issues

sameq deprecated

Option 'sameq' was removed. If you are looking for an option to preserve the quality (which is not what -sameq was for), use -qscale 0 or an equivalent quality factor option.
Failed to set value '1' for option 'sameq': Invalid argument
Error parsing global options: Invalid argument

And that's when it exits.

You probably need "-q:a 0", not sure though.

libvo-aac encoder no longer required

In newer ffmpeg versions, the external libvo-aac encoder is no longer required. The internal AAC can be used.
Source: https://ffmpeg.org/#removing_external_aac_encoders

Hence the lines:

ffmpeg -i tmpaud-clean.wav -acodec libvo_aacenc -ab 128 -ac 1 tmpaud-clean.aac
ffmpeg -i tmpaud-clean.aac -acodec copy -i tmpvid.mp4 -vcodec copy ./clean/$1

can be replaced with

ffmpeg -i tmpaud-clean.wav -i tmpvid.mp4 -vcodec copy -strict -2 ./clean/$1

(I had to add -strict -2 to the command to enable experimental codecs, using version 2.8.17, it might not be necessary with newer versions)

Btw, I just used this method to remove awful background noise (mostly laptop fan noise) from a video presentation, and it works really great, thanks!