scripts/crossfade_cat.sh

   1 #!/bin/bash
   2 #
   3 # crossfade_cat.sh
   4 #
   5 # Concatenates two files together with a crossfade of $1 seconds.
   6 # Filenames are specified as $2 and $3.
   7 #
   8 # $4 is optional and specifies if a fadeout should be performed on
   9 # first file.
  10 # $5 is optional and specifies if a fadein should be performed on
  11 # second file.
  12 #
  13 # Example: crossfade_cat.sh 10 infile1.wav infile2.wav auto auto
  14 #
  15 # By default, the script attempts to guess if the audio files
  16 # already have a fadein/out on them or if they just have really
  17 # low volumes that won't cause clipping when mixxing.  If this
  18 # is not detected then the script will perform a fade in/out to
  19 # prevent clipping.
  20 #
  21 # The user may specify "yes" or "no" to force the fade in/out
  22 # to occur.  They can also specify "auto" which is the default.
  23 #
  24 # Crossfaded file is created as "mix.wav".
  25 #
  26 # Original script from Kester Clegg.  Mods by Chris Bagwell to show
  27 # more examples of sox features.
  28 #
  29
  30 SOX=../src/sox
  31 SOXI=../src/soxi
  32
  33 if [ "$3" == "" ]; then
  34     echo "Usage: $0 crossfade_seconds first_file second_file [ fadeout ] [ fadein ]"
  35     echo
  36     echo "If a fadeout or fadein is not desired then specify \"no\" for that option.  \"yes\" will force a fade and \"auto\" will try to detect if a fade should occur."
  37     echo
  38     echo "Example: $0 10 infile1.wav infile2.wav auto auto"
  39     exit 1
  40 fi
  41
  42 fade_length=$1
  43 first_file=$2
  44 second_file=$3
  45
  46 fade_first="auto"
  47 if [ "$4" != "" ]; then
  48     fade_first=$4
  49 fi
  50
  51 fade_second="auto"
  52 if [ "$5" != "" ]; then
  53     fade_second=$5
  54 fi
  55
  56 fade_first_opts=
  57 if [ "$fade_first" != "no" ]; then
  58     fade_first_opts="fade t 0 0:0:$fade_length 0:0:$fade_length"
  59 fi
  60
  61 fade_second_opts=
  62 if [ "$fade_second" != "no" ]; then
  63     fade_second_opts="fade t 0:0:$fade_length"
  64 fi
  65
  66 echo "crossfade and concatenate files"
  67 echo
  68 echo  "Finding length of $first_file..."
  69 first_length=`$SOX --info -D "$first_file"`
  70 echo "Length is $first_length seconds"
  71
  72 trim_length=`echo "$first_length - $fade_length" | bc`
  73
  74 # Get crossfade section from first file and optionally do the fade out
  75 echo "Obtaining $fade_length seconds of fade out portion from $first_file..."
  76 $SOX "$first_file" -e signed-integer -b 16 fadeout1.wav trim $trim_length
  77
  78 # When user specifies "auto" try to guess if a fadeout is needed.
  79 # "RMS amplitude" from the stat effect is effectively an average
  80 # value of samples for the whole fade length file.  If it seems
  81 # quiet then assume a fadeout has already been done.  An RMS value
  82 # of 0.1 was just obtained from trial and error.
  83 if [ "$fade_first" == "auto" ]; then
  84     RMS=`$SOX fadeout1.wav 2>&1 -n stat | grep RMS | grep amplitude | cut -d : -f 2 | cut -f 1`
  85     should_fade=`echo "$RMS > 0.1" | bc`
  86     if [ $should_fade == 0 ]; then
  87         echo "Auto mode decided not to fadeout with RMS of $RMS"
  88         fade_first_opts=""
  89     else
  90         echo "Auto mode will fadeout"
  91     fi
  92 fi
  93
  94 $SOX fadeout1.wav fadeout2.wav $fade_first_opts
  95
  96 # Get the crossfade section from the second file and optionally do the fade in
  97 echo "Obtaining $fade_length seconds of fade in portion from $second_file..."
  98 $SOX "$second_file" -e signed-integer -b 16 fadein1.wav trim 0 $fade_length
  99
 100 # For auto, do similar thing as for fadeout.
 101 if [ "$fade_second" == "auto" ]; then
 102     RMS=`$SOX fadein1.wav 2>&1 -n stat | grep RMS | grep amplitude | cut -d : -f 2 | cut -f 1`
 103     should_fade=`echo "$RMS > 0.1" | bc`
 104     if [ $should_fade == 0 ]; then
 105         echo "Auto mode decided not to fadein with RMS of $RMS"
 106         fade_second_opts=""
 107     else
 108         echo "Auto mode will fadein"
 109     fi
 110 fi
 111
 112 $SOX fadein1.wav fadein2.wav $fade_second_opts
 113
 114 # Mix the crossfade files together at full volume
 115 echo "Crossfading..."
 116 $SOX -m -v 1.0 fadeout2.wav -v 1.0 fadein2.wav crossfade.wav
 117
 118 echo "Trimming off crossfade sections from original files..."
 119
 120 $SOX "$first_file" -e signed-integer -b 16 song1.wav trim 0 $trim_length
 121 $SOX "$second_file" -e signed-integer -b 16 song2.wav trim $fade_length
 122 $SOX song1.wav crossfade.wav song2.wav mix.wav
 123
 124 echo -e "Removing temporary files...\n"
 125 rm fadeout1.wav fadeout2.wav fadein1.wav fadein2.wav crossfade.wav song1.wav song2.wav
 126 mins=`echo "$trim_length / 60" | bc`
 127 secs=`echo "$trim_length % 60" | bc`
 128 echo "The crossfade in mix.wav occurs at around $mins mins $secs secs"
 129