Software Automatic Mouth - Tiny Speech Synthesizer
Sam is a very small Text-To-Speech (TTS) program written in C, that runs on most popular platforms. It is an adaption to C of the speech software SAM (Software Automatic Mouth) for the Commodore C64 published in the year 1982 by Don't Ask Software (now SoftVoice, Inc.). It includes a Text-To-Phoneme converter called reciter and a Phoneme-To-Speech routine for the final output. It is so small that it will work also on embedded computers. On my computer it takes less than 39KB (much smaller on embedded devices as the executable-overhead is not necessary) of disk space and is a fully stand alone program. For immediate output it uses the SDL-library, otherwise it can save .wav files.
An online version and executables for Windows can be found on the web site: http://simulationcorner.net/index.php?page=sam
Simply type "make" in your command prompt. In order to compile without SDL remove the SDL statements from the CFLAGS and LFLAGS variables in the file "Makefile".
It should compile on every UNIX-like operating system. For Windows you need Cygwin or MinGW( + libsdl).
type
./sam I am Sam
for the first output.
If you have disabled SDL try
./sam -wav i_am_sam.wav I am Sam
to get a wav file. This file can be played by many media players available for the PC.
you can try other options like -pitch number -speed number -throat number -mouth number
Some typical values written in the original manual are:
DESCRIPTION SPEED PITCH THROAT MOUTH
Elf 72 64 110 160
Little Robot 92 60 190 190
Stuffy Guy 82 72 110 105
Little Old Lady 82 32 145 145
Extra-Terrestrial 100 64 150 200
SAM 72 64 128 128
It can even sing look at the file "sing" for a small example.
For the phoneme input table look in the Wiki.
A description of additional features can be found in the original manual at http://www.retrobits.net/atari/sam.shtml or in the manual of the equivalent Apple II program http://www.apple-iigs.info/newdoc/sam.pdf
This program was converted semi-automatic into C by converting each assembler opcode. e. g.
lda 56 => A = mem[56];
jmp 38018 => goto pos38018;
inc 38 => mem[38]++;
. .
. .
Then it was manually rewritten to remove most of the jumps and register variables in the code and rename the variables to proper names. Most of the description below is a result of this rewriting process.
Unfortunately its still a not very good readable. But you should see where I started :)
First of all I will limit myself here to a very coarse description. There are very many exceptions defined in the source code that I will not explain. Also a lot of code is unknown for me e. g. Code47503. For a complete understanding of the code I need more time and especially more eyes have a look on the code.
It changes the english text to phonemes by a ruleset shown in the wiki.
The rule " ANT(I)", "AY", means that if he find an "I" with previous letters " ANT", exchange the I by the phoneme "AY".
There are some special signs in this rules like # & @ ^ + : % which can mean e. g. that there must be a vocal or a consonant or something else.
With the -debug option you will get the corresponding rules and the resulting phonemes.
Here is the full tree of subroutine calls:
SAMMain() Parser1() Parser2() Insert() CopyStress() SetPhonemeLength() Code48619() Code41240() Insert() Code48431() Insert()
Code48547
Code47574
Special1
Code47503
Code48227
SAMMain() is the entry routine and calls all further routines. Parser1 transforms the phoneme input and transforms it to three tables phonemeindex[] stress[] phonemelength[] (zero at this moment)
This tables are now changed:
Parser2 exchanges some phonemes by others and inserts new. CopyStress adds 1 to the stress under some circumstances SetPhonemeLength sets phoneme lengths. Code48619 changes the phoneme lengths Code41240 adds some additional phonemes Code48431 has some extra rules
The wiki shows all possible phonemes and some flag fields.
The final content of these tables can be seen with the -debug command.
In the function PrepareOutput() these tables are partly copied into the small tables: phonemeindexOutput[] stressOutput[] phonemelengthOutput[] for output.
Except of some special phonemes the output is build by a linear combination:
A = A1 * sin ( f1 * t ) +
A2 * sin ( f2 * t ) +
A3 * rect( f3 * t )
where rect is a rectangular function with the same periodicity like sin. It seems really strange, but this is really enough for most types of phonemes.
Therefore the above phonemes are converted with some tables to pitches[] frequency1[] = f1 frequency2[] = f2 frequency3[] = f3 amplitude1[] = A1 amplitude2[] = A2 amplitude3[] = A3
Above formula is calculated in one very good omptimized routine. It only consist of 26 commands:
48087: LDX 43 ; get phase
CLC
LDA 42240,x ; load sine value (high 4 bits)
ORA TabAmpl1,y ; get amplitude (in low 4 bits)
TAX
LDA 42752,x ; multiplication table
STA 56 ; store
LDX 42 ; get phase
LDA 42240,x ; load sine value (high 4 bits)
ORA TabAmpl2,y ; get amplitude (in low 4 bits)
TAX
LDA 42752,x ; multiplication table
ADC Var56 ; add with previous values
STA 56 ; and store
LDX 41 ; get phase
LDA 42496,x ; load rect value (high 4 bits)
ORA TabAmpl3,y ; get amplitude (in low 4 bits)
TAX
LDA 42752,x ; multiplication table
ADC 56 ; add with previous values
ADC #136
LSR A ; get highest 4 bits
LSR A
LSR A
LSR A
STA 54296 ;SID main output command
The rest is handled in a special way. At the moment I cannot figure out in which way. But it seems that it uses some noise (e. g. for "s") using a table with random values.
The software is a reverse-engineered version of a commercial software published more than 30 years ago. The current copyright holder is SoftVoice, Inc. (www.text2speech.com)
Any attempt to contact the company failed. The website was last updated in the year 2009. The status of the original software can therefore best described as Abandonware (http://en.wikipedia.org/wiki/Abandonware)
As long this is the case I cannot put my code under any specific open source software license Use it at your own risk.
If you have questions don' t hesitate to ask me. If you discovered some new knowledge about the code please mail me.
Sebastian Macke Email: sebastian@macke.de