aac2ac3

#!/bin/bash

infile=$1

filename=${infile##*/}
filepath=${infile%"$filename"}
filetitle=${filename%.*}
fileext=${filename#"$filetitle"}

outfile=${filepath}${filetitle}-aac2ac3.mkv #${fileext}

myname="${0##*/}"
fatal()   { [[ "$1" ]] && echo "$1" >&2 ; exit ${2:-1} ; }

# Check if external tools are present
if type avconv >/dev/null 2>&1; then
	conv=avconv
elif type ffmpeg >/dev/null 2>&1; then
	conv=ffmpeg
else
	fatal "Neither avconv nor ffmpeg were found. Either one is required."
fi


$conv -i "$infile" \
	-codec copy -codec:a ac3_fixed -b:a 448k "$outfile"


exit


# How to De-noise a recording
# default (ratio=0.5)
sox $input -n trim 0 $time noiseprof | sox $input $output noisered
# custom "ratio"
sox $input -n trim 0 $time noiseprof $tmp
sox  -n trim 0 $time noiseprof | sox $input  noisered
sox $input $output noisered $tmp $ratio # ratio = [0-1]

# Concatenating several wavs to create a multichannel
sox --combine merge L.wav R.wav C.wav SL.wav SR.wav surround.wav
sox --combine mix f1.wav "|sox f2.wav -p pad 4" "|sox f3.wav -p pad 8" out.wav


# Approach 1
#http://forum.xbmc.org/showthread.php?tid=62652

# extract the specified track
#mkvextract tracks "$INPUT" $TRACK:"$WORKDIR/AAC2AC3Temp.aac"

# faad outputs a raw 24 bit PCM stream (anything higher than 24 bits seems to
# introduce anomalies) which is then piped to aften and converted to a 640 kbit/s
# AC3 stream (640 kbit/s is max allowed and yields highest possible quality)
#faad -b 2 -f 2 -q -w "$WORKDIR/AAC2AC3Temp.aac" |
#aften -v 1 -b 640 -raw_fmt s24_le -raw_sr $RATE -raw_ch $CHANNELS -chmap 0 -lfe 1 - "$WORKDIR/AAC2AC3Temp.ac3"

#mkvmerge -o "$OUTPUT" "$INPUT" "$WORKDIR/AAC2AC3Temp.ac3"
#mkvmerge -o "$OUTPUT" -A "$INPUT" "$WORKDIR/AAC2AC3Temp.ac3"

##########################

# Approach 2

#To create a multichannel .ac3 you need to create first a multichannel wav.
#Of course sox comes very handy:

#sox -M L.wav R.wav C.wav SL.wav SR.wav surround.wav

# And now the ac3 encoding

#aften -b 448 -cmix 0 -smix 0 -dsur 2 -acmod 7 surround.wav surround.ac3

#-b 448 — Bitrate in kbps (4 channels: 384 kbps, 5 channels: 448 kbps)
#-smix 2 — Surround mix level ( 0: -3dB, 1: -6dB, 2: 0 )
#-dsur 2 — (2: Dolby surround encoded, 0: not indicated, 1: not Dolby surround encoded)
#-acmod 7 — Audio coding mode, or channel order (7: L,R,C,SL,SR)

#sox -m f1.wav "|sox f2.wav -p pad 4" "|sox f3.wav -p pad 8" out.wav


# My version
#mkvmerge --identify-verbose "$infile"
#File '<file>': container: QuickTime/MP4
#Track ID 1: video (avc1)
#Track ID 2: audio (mp4a)
#Track ID 2: audio (A_AAC)

#mvkextract tracks "$infile" "$id":"$tmpfile"