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+### ffx.sh
+
+quick apply audio effects w/ ffmpeg <br>
+
+<pre>
+supports
+mp3, wav, flac, ogg, opus, m4a, aac, mka
+
+features
+-bass, treble, volume, distortion
+-trim audio
+-tempo change with pitch preservation
+-pitch change with duration preservation
+
+example usage
+./ffx.sh bass audio.mp3 10 1
+
+helper commands
+ffbass "audio.mp3" 10 1 bassboosted.mp3
+bass audio.mp3 10 1
+bassboost audio.mp3
+</pre>
+
+---
+
+<pre>
+help docs
+
+help and version
+./ffx.sh --help
+./ffx.sh --version
+
+commands
+./ffx.sh bass INPUT PERCENT [FINE_DB] [OUTPUT]
+./ffx.sh treble INPUT PERCENT [FINE_DB] [OUTPUT]
+./ffx.sh volume INPUT DB [OUTPUT]
+./ffx.sh distort INPUT [DRIVE_0_TO_10] [OUTPUT]
+./ffx.sh trim INPUT START_SECONDS [END_SECONDS] [OUTPUT]
+./ffx.sh tempo INPUT SPEED_0.125_TO_8 [OUTPUT]
+./ffx.sh pitch INPUT SEMITONES_-36_TO_36 [OUTPUT]
+
+bass and treble
+./ffx.sh bass song.mp3 25 1 bass-song.mp3
+./ffx.sh treble song.mp3 20 1 bright-song.mp3
+
+33 = 16.5 db
+66 = 33 db
+100 = 50 db
+fine_db is added or subtracted afterward.
+
+volume
+./ffx.sh volume song.mp3 -6 quieter-song.mp3
+./ffx.sh volume song.mp3 3 louder-song.mp3
+
+distortion
+./ffx.sh distort guitar.wav 5 distorted-guitar.wav
+
+trim audio
+./ffx.sh trim song.mp3 10 30 clip.mp3
+./ffx.sh trim podcast.mp3 30 60 no-intro.mp3
+
+tempo with pitch preservation
+./ffx.sh tempo lecture.mp3 1.5 fast-lecture.mp3
+./ffx.sh tempo song.mp3 0.75 slower-song.mp3
+
+pitch with duration preservation
+./ffx.sh pitch vocal.wav 3 higher-vocal.wav
+./ffx.sh pitch vocal.wav -5 lower-vocal.wav
+
+convert while editing
+./ffx.sh volume input.wav -3 output.mp3
+
+automatic output filename
+./ffx.sh bass song.mp3 30
+
+input:  star.mp3
+output: star333033.mp3
+</pre>
+
+<pre>
+install helper commands
+./ffx.sh --add-helper-cmd
+
+remove helper commands
+./ffx.sh --remove-helper-cmd
+
+cmd helpers
+  ffbass   INPUT PERCENT [FINE_DB] [OUTPUT]
+  fftreble INPUT PERCENT [FINE_DB] [OUTPUT]
+  ffvolume INPUT DB [OUTPUT]
+  ffdistort INPUT [DRIVE_0_TO_10] [OUTPUT]
+  fftrim   INPUT START_SECONDS [END_SECONDS] [OUTPUT]
+  fftempo  INPUT SPEED_0.125_TO_8 [OUTPUT]
+  ffpitch  INPUT SEMITONES_-36_TO_36 [OUTPUT]
+
+defaults
+-output uses the source extension and a unique suffix.
+-use an explicit filename ending in .mp3 for mp3 output.
+
+examples
+ffbass "audio.mp3" 33 2
+ffbass "song.wav" 33 2 "bass.mp3"
+fftreble "song.flac" 66 -4 "treble.flac"
+ffvolume "song.mp3" -3
+ffdistort "song.wav" 4 "distorted.mp3"
+fftrim "song.mp3" 12.5 48 "clip.mp3"
+fftempo "song.mp3" 0.5 "slow.mp3"
+ffpitch "song.mp3" -3 "lower.mp3"
+</pre>