sox: modify RMS value for wav

安裝:
sudo apt-get install sox

audio info

soxi xxx.wav
sox xxx.wav -n stats

#!/bin/sh

if [ "$1" = "-h" ]; then
    echo " Usage:  ./test2.sh -22.99
      This will generate a new file that to modify the volume value
      "
    exit 0
fi
echo

##############  start work #############
target=$(echo | awk "{print $1}" | sed 's/-//g') #取正數
$(mkdir new_files)
for file in *.wav
do
    RMS_lev=$(sox $file -n stats 2>&1 | grep "RMS lev dB" | cut -d " " -f 7)
    echo $file="$RMS_lev"
    diff=$(echo | awk "{print $target+$RMS_lev}")
    #echo $diff
    intV=$(echo $diff | cut -d "." -f 1) #整數
    #echo $intV
    if [ $intV -lt 0 ]; then  #小於
        echo "< 0"
        a=$(echo | awk "{print $diff}" | sed 's/-//g') #取正數
        sox $file new_files/$file vol $a dB
    elif [ $intV -eq -0 ]; then
        echo "= -0"
        a=$(echo | awk "{print $diff}" | sed 's/-//g') #取正數
        sox $file new_files/$file vol $a dB
    elif [ $intV -eq 0 ]; then
        echo "= 0"
        sox $file new_files/$file vol -$diff dB
    else
        echo "> 0"
        sox $file new_files/$file vol -$diff dB
    fi  
done

sox command:
1. sox xxx.wav -n stats
2. sox xxx.wav -n stat
3. sox infile.wav outfile.wav vol 3 dB stats


ref:
1. 使用awk进行数字计算，保留指定位小数
2. stackoverflow
3. ubuntu forums