audio_manip.sh

# separated IN + OUT to one stereo

filename="my_audio"
ffmpeg -i $filename-in.mp3 -i $filename-out.mp3 -filter_complex "[0]apad[a];[a][1]amerge[aout]" -map "[aout]" $filename.mp3

# Mono to stereo
ffmpeg -i mono.wav -ac 2 stereo.wav

# Stereo to mono
ffmpeg -i stereo.wav -ac 1 mono.flac


# Get audio file characteristics
ffprobe -i audio_file.mp3 -v error -show_entries 'stream=codec_type,channels,channel_layout,sample_rate,duration'

# Convert to mp3
# -vn : ensure no video, not even a cover
# -ar : audio sampling frequency. Use the one shown by doing a `ffmpeg -i input.wav`
# -ac 2 : ensure stereo
# -b:a 192k : ensure biterate of 192k
ffmpeg -i input.wav -vn -ar 8000 -ac 2 -b:a 192k output.mp3

# MP3 to Raw PCM
ffmpeg -i input.mp3 -acodec pcm_s16le -f s16le -ac 1 -ar 8000 output.pcm

# Stereo to Stereo with left channel muted
ffmpeg -i stereo.wav -af "pan=stereo|c1=c1" left_muted_stereo.wav