On 9/16/18, Michael Koch <astroelectro...@t-online.de> wrote: >> Filter inputs will be auto-converted from any non-float formats to >> float or double one. Float/double formats are in [-1 .. +1] interval. > > Thank you very much for the amultiply filter, it works great! > > Here is an example for an ultrasonic converter which downconverts the > 15kHz - 25kHz band to the 0 - 10kHz band. > > First make an input file for testing. This is a 2 second 19kHz tone > followed by 2 seconds silence: > > c://ffmpeg/ffmpeg -f lavfi -i > "sine=frequency=19000:sample_rate=48000:duration=2" -af apad -t 4 > ultrasonic.wav > > Then use the downconverter: > > c://ffmpeg/ffmpeg -i ultrasonic.wav -f lavfi -i > "sine=frequency=15000:sample_rate=48000" -filter_complex > "[0]highpass=f=15000,highpass=f=15000,highpass=f=15000,highpass=f=15000[sound];[1]volume=8[sine];[sound][sine]amultiply[mixed];[mixed]lowpass=f=10000,lowpass=f=10000,lowpass=f=10000,lowpass=f=10000" > out.wav
Nice, it might be better to use aevalsrc, because it have multichannel output. For stronger highpass/lowpass you can use aiir filter if you know correct parameters. _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
