convert_to_portable_flac.sh

#!/bin/sh
target_sample_rate="48000"
target_bit_depth="16"

sample_rate=$(soxi -r "$1")
bit_depth=$(soxi -b "$1")

if [ "$sample_rate" -le "$target_sample_rate" ] && [ "$bit_depth" -le "$target_bit_depth" ]; then
  cp "$1" "$2"
else
  if [ "$sample_rate" -lt "$target_sample_rate" ]; then
    target_sample_rate="$sample_rate"
  elif [ "$sample_rate" -eq "88200" ] || [ "$sample_rate" -eq "176400" ] || [ "$sample_rate" -eq "352800" ]; then
    target_sample_rate="44100"
  fi

  sox "$1" -G -b $target_bit_depth -r $target_sample_rate "$2"
fi