![]() Reduce broadband noise from stream using Non-Local Means. Second check the filter api (ffmpeg -h filter=anlmdn)( ) Filter anlmdn (one noise sample from the same mic / setup should be fine for all clips from that setup.)įor my heavy broadband noise I attempted The Audacity Noise Reduction, and Noise Gate. And of course you need manual intervention, unless you have a noise sample in a separate file that will be appropriate for multiple input files. You'd need a bunch of voodoo with stream split / time-range extract. But that makes it a lot less easy to use than most ffmpeg filters. So yeah, a 2nd input, rather than 2pass, would make sense. It needs to see a sample of JUST noise to set thresholds for each FFT bin. And you SHOULDN'T feed it the whole audio stream as a noise sample, anyway. Since it only needs a few seconds to get a noise profile, it's not like it has to read through the whole file. Maybe implementing it as a filter with 2 inputs, instead of a 2-pass filter, would work best. Porting that filter to ffmpeg would be a bit awkward. ![]() See also Audio noise reduction: how does audacity compare to other options? for more details of how it works, and that thresholding FFT bins in one way or another is the basis of typical commercial noise-reduction filters, too. Since the energy of the noise is spread over the whole spectrum, only letting through a few narrow bands of it will reduce the total noise energy a LOT. ![]() It's like a band-pass filter that adapts to the signal. It can do amazing things without causing problem. So it only lets signals through when they're louder than the noise floor in that frequency band. (basically: suppress every FFT bin that's below the threshold. The comments at the top of explain how it works. Audacity has a fairly effective NR filter, but it's designed to be used with 2-pass operation with a sample of just the noise, and then the input. (Human speech can still sound ok in a pretty narrow bandpass, but there are much better ways to clean up a broadband noise background hiss.)įfmpeg doesn't have any decent audio filters for noise-reduction built in. Update: FFmpeg recently added afftdn which uses the noise threshold per-FFT-bin method described below, with various options for adapting / figuring out appropriate threshold values on the fly.Īnlmdn (non-local means) is a technique that works well for video I haven't tried the audio filter.Įither of these should be much better than highpass / lowpass, unless your only noise is a 60Hz hum or something. What am I missing?Īlso, I read about weiner filters that could be used for speech enhancements and found this but am not sure how to use it. ![]() My reasoning was that since speech comes under 300-3000 hz range I can filter out all other frequencies to suppress any background noise. Till now I have tried following filters: ffmpeg-20140324-git-63dbba6-win64-static\bin>ffmpeg -i i nput.wav -filter_complex "highpass=f=400,lowpass=f=1800" out2.wavįfmpeg -i i nput.wav -af "equalizer=f=1000:width_type=h:width=900:g=-10" output.wavįfmpeg -i i nput.wav -af "bandreject=f=1200:width_type=h:width=900:g=-10" output.wavīut the results are very disappointing. I am using ffmpeg to do all of this stuff, but am stuck at the noise reduction phase. I want to reduce the background noise of the audio so that the speech that I relay to my speech recognition engine is clear. These videos come from mobile/other handmade devices and hence contain a lot of noise. I extract audio clips from a video file for speech recognition.
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