Talking clock, written in bash using common utilities

Contents

• Overview
• Setup
• Sampling
• Basic talking clock script
• Advanced talking clock script
• Voice modulation
• Automating
• Final notes
• Downloads and links

Overview

What we want to do is very simple (in principle), just automate a speaking clock.
Take a string "07:24PM" and build a set of commands that would recreate the spoken version, 'oh','seven','twenty','four',PM'.
After we have this basic talking clock we want to add some fun, like delayed once an hour utterances and random voice modulation.

Setup

The main tools required for this project are a working sound card/microphone, a sound recorder and a sound player.
You could skip the recording part if you had all the samples from another source, like a text to speech program, but where's the fun in that ?
Any Linux/*inx setup should have access to the 'date' command and the bash shell of a reasonable version.

Sampling

Most Linux systems now a days use the ALSA sound system, if you setup uses something else (like oss) then please check your documentation.
Plug in a your microphone and with the speakers turned up fair way, if you hear nothing out of the speakers you most likely need to unmute your microphone channel.
Run your favorite audio mixer program or alsamixer.
To unmute the microphone channel in alsamixer use the Left and Right cursor keys to select the channel and press 'm' to mute/unmute.
ALSA also comes with amixer that can be automated
amixer sset Mic unmute unmutes and
amixer sset Mic mute mutes the microphone.
I also had a 'Mic boost' channel on my sound card that had to be unmuted to provide a decent volume.

Sockssox (SOund eXchange) is the swiss army knife of sound processing programs and can convert almost all sound sample formats. It also comes with the ability to process effects into samples and play and record sounds.
sox has been around for many many years and should be available to just about any platform including windows and the Atari ST.
Saying that, if you have favorite sound recording program you are free to use that. I found the graphical mhwaveedit very useful.

We need to collect 28 samples, but do not worry they are all short and it will take no time at all.

• 'zero' or 'oh' - 0.wav
• 'one' - 1.wav
• 'two' - 2.wav
• 'three' - 3.wav
• 'four' - 4.wav
• 'five' - 5.wav
• 'six' - 6.wav
• 'seven' - 7.wav
• 'eight' - 8.wav
• 'nine' - 9.wav
• 'ten' - 10.wav
• 'eleven' - 11.wav
• 'twelve' - 12.wav
• 'thirteen' - 13.wav
• 'fourteen' - 14.wav
• 'fifteen' - 15.wav
• 'sixteen' - 16.wav
• 'seventeen' - 17.wav
• 'eighteen' - 18.wav
• 'nineteen' - 19.wav
• 'twenty' - 20.wav
• 'thirty' - 30.wav
• 'forty' - 40.wav
• 'fifty' - 50.wav
• 'PM' - pm.wav
• 'AM' - am.wav

File names are important for the next stage.
To record a sample with sox type rec 0.wav when you finish recording just hit CTRL+c

We are using .wav files simply because they are a non-compressed lossless format that is well know to a large number of sound programs. Feel free to use .mp3, .ogg or any other format that you wish, but remember compressed files have to be uncompressed before they can be used and this may take time or/and excessive CPU processing.

Finally make sure the samples sound as you wish by playing them back.
To play back a sample with sox use play 0.wav, we can also chain samples together
play 0.wav; play 7.wav; play 20.wav; play 4.wav; play pm.wav (the play command has a ability to play multiple files per inception, but we will not be using that)

If you are boring you may want to try the VERY poor voice samples I made, located in the Downloads and links section.

Basic talking clock script

The programming language we are going to use to provide the speaking clock with automation is Bash shell script.
To start all bash shell scripts we have a "shebang", which is a comment telling any program that is interested that this file should be interpreted with /bin/bash.

01#!/bin/bash

We can also add some comments so we know what this file is supposed to do.

03# basic.sh - a talking clock using voice samples
04# more information available at http://www.jumpstation.co.uk/scripts/talkingclock/

The 'date' command simply prints the date and time (try it)date. If only we could get that result in a more handy format ...
date --help shows there are many ways of formating the output.

06hours=`date +"%-l"`

Will assign the variable [hours] with the result of the date +"%-l" command. Note the use of back-ticks `, not single quotes'. we do the same with [mins] and [ampm] and we end up with

01#!/bin/bash
02
03# basic.sh - a talking clock using voice samples
04# more information available at http://www.jumpstation.co.uk/scripts/talkingclock/
05
06hours=`date +"%-l"`
07mins=`date +"%-M"`
08ampm=`date +"%-P"`

Add some magic 'play' commands and we have a very basic talking clock.

01#!/bin/bash
02
03# basic.sh - a talking clock using voice samples (basic version)
04# more information available at http://www.jumpstation.co.uk/scripts/talkingclock/
05
06hours=`date +"%-l"`
07mins=`date +"%-M"`
08ampm=`date +"%-P"`
09
10play $hours.wav
11play $mins.wav
12play $ampm.wav

Save this as basic.sh and run sh basic.sh if the voice samples are in the same directory you should hear the time spoken.

But wait, this only works if the minutes are 0-21,30,40 or 50, OK time to make this a bit more complex.
Other values will give an error sox: Can't open input file '.wav': No such file or directory

Advanced talking clock script

When writing complex code it is a good idea to modularise as much as possible, this makes reading and reusing code much easier.
We want a function for "hours","mins","AM/PM" and one to handle the actual playing of the samples, this makes it easy to change for the Voice modulation section.

[$1] represents the first value passed to the function, this will make more sense later.
Looks familiar, now we need that [wavplay] function
hmmm, that was all very simple, lets look at how the script looks at the moment
Wait a minute why is the sayMins $mins line commented out #sayMins $mins ? Because the [sayMins] function is a bit more complex.
Lets add it now
Woh! thats a bit more complex, never fear, I will break it down. Now as the comment says, we need to deal with three circumstances.

1. 0-9
we want to utter an 'oh' before each number, e.g. 'oh','seven' for seven minutes past the hour.
2. 10-19
each of these exist as an individual file so we do nothing extra.
3. 20-59
we want to utter the correct decimal, e.g. 'twenty','four' for 24 but only 'twenty' for 20 not 'twenty','oh'

First job is to take the number and split it into its possible components
The ${} implies an action on an existing variable, the first 1 is the $1 we see in the other functions, the second value (0 for $tens and 1 for $units) is the starting point in the string, the third value is the length of the string.
so word=${word:0:3} when $word is 'google' the result is 'goo'
Because the value passed into the function from the 'date' command might only be one character i.e. 0-9 the first thing we need to check is if anything is in the $units variable. The ${#units} returns the length of the string value contained in $units, if this is zero then the variable is empty.
The spacing in bash script if statements is VERY important if [ ${#units} = 0 ]; then

When we find the $units is empty it will be because the single value fitted in $tens. to get what we want we swap it around a bit.

At this point, we have a value in $tens and a value in $units, time to get to work.
if [ $tens -lt 1 ]; then will be true if $tens is less than '1' i.e. '0'
in which case, play the 'oh' followed by the unit value.
elif [ $tens -lt 2 ]; then will be true if $tens is less than '2' i.e. '0' or '1', but as the code already deals with '0', the condition only returns true if $tens is '1'
in which case, play the original value passed to the function as it will be 10-19
else will be true if all the previous conditions returned false.
So play the tens part, 2,3,4 and 5 become 20,30,40 and 50 If there are any units greater than '0' then we need to say them as will otherwise our job is done.

Here is the full code, save it as lessbasic.sh
run sh lessbasic.sh to test it.
You can change the call 'sayMins $mins' at the end to test it works with all values rather than waiting for the right time of day.

Automating

So we have our voice changing talking clock that runs on command, this final section adds automation so that the talking clock is called upon once and hour after a random number of minutes.

The 'cron' daemon commonly has the task of controling scheduled tasks.
To add a new task use the command crontab -e
Add a new line 0 * * * * sleep $(($RANDOM\%60))m; /pathToTheScript/timeis.sh
This will run at '0' minutes past the hour but will sleep for a random number of minutes 0-59, once the sleep command has finished the next command is our 'timeis' script, note: you must use the full path to the script.
The '\' before the '%' percent sign is required in contab files, but not at the command line.
The semicolon';' can be used to chain commands together, try.
date ; sleep $(($RANDOM%60))s ; date
man crontab will tell you more about controling the 'cron' daemon.

Downloads and links

basic.sh - The basic example.
lessbasic.sh - follows on from the basic example.
timeis.sh My final version of the timeis.sh.
voice.bzip2 (81k) My voice files, VERY poor quality, I am sure you can do better.

ALSA
bash shell
date command
sox (SOund eXchange)
mhwaveedit
audacity
glame
xmms
cron