Freepbx Voicemail Transcription Script: Google Speech API

## sendmail-gcloud
#!/bin/sh

# sendmail-gcloud
#
# Original source created by N. Bernaerts: https://github.com/NicolasBernaerts/debian-scripts/tree/master/asterisk
# modified per: https://jrklein.com/2015/08/17/asterisk-voicemail-transcription-via-ibm-bluemix-speech-to-text-api/
# modified per: https://gist.github.com/lgaetz/2cd9c54fb1714e0d509f5f8215b3f5e6
# current version: https://gist.github.com/tony722/7c6d86be2e74fa10a1f344a4c2b093ea
#
#
# Notes: This is a script modified from the original to work with a FreePBX Distro PBX so that email notifications sent from
#        Asterisk voicemail contain a a speech to text transcription provided by Google Cloud Speech API
#
# License: There are no explicit license terms on the original script or on the blog post with modifications
#          I'm assumig GNU/GPL2+ unless notified otherwise by copyright holder(s)
#
# Usage: copy this file to /usr/sbin/ set ownership to asterisk:asterisk and make it executable.
#        In the [general] section of /etc/asterisk/voicemail.conf set mailcmd=/usr/sbin/sendmail-gcloud
#            or in FreePBX 14 GUI go to Settings->Voicemail->Email Config->Mail Command to set this.
#        This script also uses dos2unix, ensure it is executable by the asterisk user (chmod 777)
#
# Requirements:
#   Google Cloud services account (paid--free trial available) with Google Speech to Text API enabled
#   gcloud cli utility https://cloud.google.com/sdk/docs/downloads-yum
#      gcloud utility must be authenticated. Before doing this, 'su asterisk' so authentication happens in the correct user account
#      authenticate with: gcloud auth login
#      select project: gcloud config set project <Project ID>
#   jq (yum install jq)
#   sox with flac
#
# Version History:
# 2019-02-27  Initial commit by tony722

# set PATH
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

# save the current directory
pushd .

# create a temporary directory and cd to it
TMPDIR=$(mktemp -d)
cd $TMPDIR

# dump the stream to a temporary file
cat >> stream.org

# get the boundary
BOUNDARY=$(grep "boundary=" stream.org | cut -d'"' -f 2)

# if mail has no boundaries, assume no attachment
if [ "$BOUNDARY" = "" ]

then
	# send the original stream
	mv stream.org stream.new
else
	# cut the original stream into parts
	# stream.part  - header before the boundary
	# stream.part1 - header after the bounday
	# stream.part2 - body of the message
	# stream.part3 - attachment in base64 (WAV file)
	# stream.part4 - footer of the message
	awk '/'$BOUNDARY'/{i++}{print > "stream.part"i}' stream.org

	# cut the attachment into parts
	# stream.part3.head - header of attachment
	# stream.part3.wav.base64 - wav file of attachment (encoded base64)
	sed '7,$d' stream.part3 > stream.part3.wav.head
	sed '1,6d' stream.part3 > stream.part3.wav.base64

	# convert the base64 file to a wav file
	dos2unix -o stream.part3.wav.base64
	base64 -di stream.part3.wav.base64 > stream.part3.wav

	# convert the wav file to FLAC
	sox -G stream.part3.wav --channels=1 --bits=16 --rate=8000 stream.part3.flac

	# convert to MP3
	sox stream.part3.wav stream.part3-pcm.wav
	lame -m m -b 24 stream.part3-pcm.wav stream.part3.mp3
	base64 stream.part3.mp3 > stream.part3.mp3.base64

	#create mp3 mail part
	sed 's/x-[wW][aA][vV]/mpeg/g' stream.part3.wav.head | sed 's/.[wW][aA][vV]/.mp3/g' > stream.part3.new
	dos2unix -o stream.part3.new
	unix2dos -o stream.part3.mp3.base64
	cat stream.part3.mp3.base64 >> stream.part3.new

	RESULT=`gcloud ml speech recognize stream.part3.flac --language-code='en-US'`

	FILTERED=`echo "$RESULT" | jq -r '.results[].alternatives[].transcript'`

	# generate first part of mail body, converting it to LF only
	mv stream.part stream.new
	cat stream.part1 >> stream.new
	sed '$d' < stream.part2 >> stream.new

	# beginning of transcription section
	echo "" >> stream.new
	echo "--- Google transcription result ---" >> stream.new

	# append result of transcription
	if [ -z "$FILTERED" 	]
	then
	  echo "(Google was unable to recognize any speech in audio data.)" >> stream.new
	else
	  echo "$FILTERED" >> stream.new
	fi

	# end of message body
	tail -1 stream.part2 >> stream.new

	# add converted attachment
	cat stream.part3.new >> stream.new

	# append end of mail body, converting it to LF only
	echo "" >> stream.tmp
	echo "" >> stream.tmp
	cat stream.part4 >> stream.tmp
	dos2unix -o stream.tmp
	cat stream.tmp >> stream.new

fi

# send the mail thru sendmail
cat stream.new | sendmail -t

# go back to original directory
popd

# remove all temporary files and temporary directory
rm -Rf $TMPDIR