ffmpeg brown noise

brown-noise

# stereo, lowered
ffplay -nodisp -f lavfi "anoisesrc=c=brown:a=0.25 [a];anoisesrc=c=brown:a=0.25 [b];[a][b]amerge,lowpass=f=80"

## oscilating general
ffplay \
  -nodisp \
  -f lavfi \
  "anoisesrc=c=brown:a=1 [a];anoisesrc=c=brown:a=1 [b]; [a][b]amerge,lowpass=f=80,volume='0.6+0.4*sin(2*PI*time(0)/12)'"

## L-R independent oscilation (3s cycle 1-0.3 volume)
ffplay \
  -f lavfi \
  "anoisesrc=c=brown:r=22050:a=1,
   volume='0.65+0.35*sin(2*PI*t/4)':eval=frame[a];
   anoisesrc=c=brown:a=1,
   volume='0.65+0.35*sin(2*PI*t/4+PI)':eval=frame[b];
   [a][b]amerge,lowpass=f=80"

### save to file
ffmpeg -f lavfi -t 60 -i "
 anoisesrc=c=brown:r=22050:a=1,
 volume='0.65+0.35*sin(2*PI*t/4)':eval=frame[a];
 anoisesrc=c=brown:r=22050:a=1,
 volume='0.65+0.35*sin(2*PI*t/4+PI)':eval=frame[b];
 [a][b]amerge=inputs=2,lowpass=f=80" \
 -ac 2 \ 
 -ar 44100 \ 
 -c:a pcm_s16le oscillating_low_brown-noise_1min_44k.wav

### nice lowpass values (to lower)
lowpass=120
lowpass=80
lowpass=50