[LAD] Normalize and Cut Wav

Alfs Kurmis kallipygos at inbox.lv
Tue Mar 8 21:44:46 UTC 2011

 Hi experts.
 I have started my small project - mp3 database for radio.
 How do i normalize by peak [not RMS] and trim silences in begin and
 end of WAV files ?
 Silences somewhere in middle of file i wanna leave untouched.
 I wanna in first step detect MAX sample in whole WAV file.
  For example we gotta MAX sample 10 000, then Apmliefier_coefficient
 will be 32 000/10 000 = 3,2 .
 In second step i wanna trim silences at begin and below -80 dB [or 2
 bit noise]
  For this in same file each sample multiple by Apmliefier_coefficient
 , and see - result is over  -80 dB or not.
 If not, then first N samples will not written in trimmed file, but
 first sample that is over  -80 dB [in any channel] ,
 and all further samples written in new file.
 Now we must just follow which sample  [in any channel] is  over  -80
 After write is complete, we can just truncate after last sample that
 was  over  -80 dB, and write header.
 So far i have found SOX vanna reverse da file for end silence trim,
 and for each step produce tmp file.
   Is here C API , program, script, way to do so what without any
 temporary files ?
 I have written script for normalize, but what ir best way for
 normalize ?
 What about mp3 and ogg  automatic normalize and frames trim ?
 Tnx in advance
 for i in *.wav; do
  echo "** Check peak for $i **"
   ampl=`sox "$i" -t wav /dev/null stat -v 2>&1`
   wert1="1.1";  wert2=$ampl;
   wahr=$(echo  "$wert1 >  $wert2" | bc)
   if  [ $wahr = 1 ]; then
     echo "  $wert1 > $wert2 , Do Nuthin"
     echo "  $wert1 <= $wert2 , Do process"
     echo "** Amplifying volume by  -=$ampl=-  to fake a normalize  
 $val.wav  --  $waveaus"
     ampl2=$(echo $ampl*0.9995 | bc -l)
     echo "ampl2 = $ampl2"
     sox -v $ampl2  "$i"  -t wav  "$waveaus"
 echo ""
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