Asterisk Voicemail --> MP3 w/ IBM bluemix trasnscription

sendmail.asterisk

#!/bin/sh
# Asterisk Voicemail -> MP3 And IBM Bluemix Transscription
#
# Based on multiple peoples work:
# Asterisk voicemail attachment conversion script
# Revision history :
# 22/11/2010 - V1.0 - Creation by N. Bernaerts
# 07/02/2012 - V1.1 - Add handling of mails without attachment (thanks to Paul Thompson)
# 01/05/2012 - V1.2 - Use mktemp, pushd & popd
# 08/05/2012 - V1.3 - Change mp3 compression to CBR to solve some smartphone compatibility (thanks to Luca Mancino)
# 01/08/2012 - V1.4 - Add PATH definition to avoid any problem (thanks to Christopher Wolff)
# 16/07/2015 - V1.5 - Handle natively GSM WAV (thanks to Michael Munger)

# Also stole the work of:
# 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/
#
# 2017-09-17 Initial commit by lgaetz, working but unpolished
# 2017-09-18 Original attachment added to email
# 2017-09-18 working with email sans attachments
#
#
# 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.asterisk
#
# Permissions - More: Make sure the asterisk user can execute (and that they exist - fwiw, a new 
#                     install of FreePBX circa March 2020, I didn't need to change or install anything):
#   * dos2unix
#   * unix2dos
#   * sox
#   * lame
#



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


# Specify IBM Bluemix API credentials
API_KEY="XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
API_URL="https://api.us-south.speech-to-text.watson.cloud.ibm.com/instances/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/v1/recognize"
API_OPTS="?model=en-US_NarrowbandModel"


# save the current directory
pushd .
 
# create a temporary directory and cd to it
TMPDIR=$(mktemp -d /tmp/astVM.XXXXXXXXXX)
cd $TMPDIR
 
# dump the stream to a temporary file
cat >> stream.org
 
# get the boundary
BOUNDARY=$(grep "boundary=" stream.org | cut -d'"' -f 2)
 
# cut the file 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
 
# if mail is having no audio attachment (plain text)
PLAINTEXT=$(cat stream.part1 | grep 'plain')
if [ "$PLAINTEXT" != "" ]
then
 
  # prepare to send the original stream
  cat stream.org > stream.new
 
# else, if mail is having audio attachment
else
 
  # 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

  # Send WAV to Watson Speech to Text API. Must use "Narrowband" (aka 8k) model since WAV is 8k sample
  CURL_OPTS=""
  curl -s $CURL_OPTS -k -u "apikey:$API_KEY" -X POST \
    --limit-rate 40000 \
    --header "Content-Type: audio/wav" \
    --data-binary @stream.part3.wav \
    "$API_URL$API_OPTS" 1>audio.txt

  # Extract transcript results from JSON response
  TRANSCRIPT=`cat audio.txt | grep transcript | sed 's#^.*"transcript": "##g' | sed 's# "$##g'`

  # convert wave file (GSM encoded or not) to PCM wav file
  sox stream.part3.wav stream.part3-pcm.wav
 
  # convert PCM wav file to mp3 file
  # -b 24 is using CBR, giving better compatibility on smartphones (you can use -b 32 to increase quality)
  # -V 2 is using VBR, a good compromise between quality and size for voice audio files
  lame -m m -b 24 stream.part3-pcm.wav stream.part3.mp3
 
  # convert back mp3 to base64 file
  base64 stream.part3.mp3 > stream.part3.mp3.base64
 
  # generate the new mp3 attachment header
  # change Type: audio/x-wav or audio/x-WAV to Type: audio/mpeg
  # change name="msg----.wav" or name="msg----.WAV" to name="msg----.mp3"
  sed 's/x-[wW][aA][vV]/mpeg/g' stream.part3.wav.head | sed 's/.[wW][aA][vV]/.mp3/g' > stream.part3.mp3.head
 
  # 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 -e "\n--- Automated transcription result ---\n " >> stream.new

  # append result of transcription
  echo "$TRANSCRIPT" >> stream.new

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

  cat stream.part3.mp3.head >> stream.new
  dos2unix -o stream.new
 
  # append base64 mp3 to mail body, keeping CRLF
  unix2dos -o stream.part3.mp3.base64
  cat stream.part3.mp3.base64 >> 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
# if things are not working, this is a great place to
# start.  If, as in my experience, you can't find the
# temp folder than, check your spelling that FreePBX 
# is trying to run the right script.

rm -Rf $TMPDIR

Couple of things for debugging purposes that it took a while for me to notice:

1.) FreeBPX / Asterisk don't appear to tell you if it can't find the script (this was not the correct filename at that point)

DEBUG[24625][C-00000187] app_voicemail.c: Sent mail to <redacted> with command '/usr/sbin/sendmial.asterisk'

2.) If you do turn off removal of the temp directory to pipe the steam file in again:

# cat /tmp/astVM-XXXXXXXX/stream.org | /usr/sbin/sendmail.asterisk

IT WILL NOT APPEAR. There is a message-ID header in there, duplicates are ignored, at least by gmail - change it a bit each time.

3.) Errors from IBM are accessible in the audio.txt file in the created temp directory