Images to sound and back

[ljones]

Hello all

Ok I know this is going to sound a little bit weird. But I recently just stumbled over this website;

foxular.net/img2wav/

On it, it has two perl programs -- both of which do something relatively unusual. One converts a .png image into .wav file; the other perl program does the opposite.

I know this sounds like a weird request and after looking at the two perl programs they look to be relatively simple. I even managed to get them to work on my slackware box!

Then I suddenly thought -- could these be rewritten in bacon?

I've managed to work out how to read simple pictures (such as PPM) before, in fact I once made a program to convert a small .PPM (like a avatar image for example) into forum code. Here's what I came up with;


OPEN "1.ppm" FOR READING AS myfile

READLN i1$ FROM myfile
READLN i2$ FROM myfile
READLN i3$ FROM myfile
READLN i4$ FROM myfile

A=INSTR(i3$," ")
x$=MID$(i3$,1,A-1)
y$=MID$(i3$,A+1,LEN(i3$))

xsize=VAL(x$)
ysize=VAL(y$)

FOR y=1 TO ysize
FOR x=1 TO xsize

b1=MEMORY(1)
GETBYTE b1 FROM myfile SIZE 1
red=PEEK(b1)

b2=MEMORY(1)
GETBYTE b2 FROM myfile SIZE 1
green=PEEK(b2)

b3=MEMORY(1)
GETBYTE b3 FROM myfile SIZE 1
blue=PEEK(b3)

FREE b1
FREE b2
FREE b3

h1$=HEX$(red)
IF red < 16 THEN h1$=CONCAT$("0",h1$)
h2$=HEX$(green)
IF green < 16 THEN h2$=CONCAT$("0",h2$)
h3$=HEX$(blue)
IF blue < 16 THEN h3$=CONCAT$("0",h3$)

PRINT "[color=";
PRINT "#";
PRINT h1$;
PRINT h2$;
PRINT h3$;
PRINT "]";

PRINT CHR$(226);
PRINT CHR$(150);
PRINT CHR$(136);

PRINT "[/color]";

NEXT

PRINT

NEXT

CLOSE FILE myfile


Now what I'm thinking is if I can somehow replace the writing to forum-style code to data for a wav file, this idea might work. The only snag is (cue drum roll!) I have no idea on how to create a wav file in bacon!

Is there a way to read/write wav's in bacon at all?

Thanks

BTW Sorry if this post appears more than once. Something went wrong with posting .

ljones

[Pjot]

Interesting!

BaCon has an interface to connect to the Open Audio Library.

So I guess your best option to create WAV files is by looking at their documentation...

Regards
Peter

[ljones]

Did not know about that interface, thanks for that ! Will need to look through it all though having looked I wonder if openal allows for "just writing into a file" so to speak, so instead of capturing off a sound card you write the data in via a program. What I'm meaning is this (imaginary code coming up);

.
..
..
FOR X=0 TO 400
Y%=90+80*SIN(X/20)
PRINT#1,CHR$(Y%);
NEXT
..
..


I know that's not even proper code, just made up but it produces a sine wave. So write that into a file but as a WAV instead of reading the input from a sound card's line in or mic port.

BTW The second line of that is from the Commodore 64 Reference guide. Some things stick long in the memory!

ljones

[ljones]

I might be already answering my own question. Uh oh!

OPEN "test.wav" FOR WRITING AS myfile

REM allocate memory 64K
bin=MEMORY(65535)

REM RIFF
POKE bin,ASC("R")
POKE bin+1,ASC("I")
POKE bin+2,ASC("F")
POKE bin+3,ASC("F")

REM File length - 8
POKE bin+4,247
POKE bin+5,255
POKE bin+6,0
POKE bin+7,0

REM WAVE
POKE bin+8,ASC("W")
POKE bin+9,ASC("A")
POKE bin+10,ASC("V")
POKE bin+11,ASC("E")

REM fmt
POKE bin+12,ASC("f")
POKE bin+13,ASC("m")
POKE bin+14,ASC("t")
POKE bin+15,32

REM File length (FMT data = 16 bytes)
POKE bin+16,16
POKE bin+17,0
POKE bin+18,0
POKE bin+19,0

REM Format tag (1=PCM)
POKE bin+20,1
POKE bin+21,0

REM Channels (1=mono,2=stereo)
POKE bin+22,1
POKE bin+23,0

REM Samples per second (68+172*256)=44100
POKE bin+24,68
POKE bin+25,172
POKE bin+26,0
POKE bin+27,0

REM Bytes per second
POKE bin+28,136
POKE bin+29,88
POKE bin+30,1
POKE bin+31,0

REM Block Align
POKE bin+32,2
POKE bin+33,0

REM bits 8 or 16
POKE bin+34,16
POKE bin+35,0

REM "DATA"
POKE bin+36,ASC("d")
POKE bin+37,ASC("a")
POKE bin+38,ASC("t")
POKE bin+39,ASC("a")

REM length of data block
POKE bin+40,255
POKE bin+41,255
POKE bin+42,0
POKE bin+43,0

start=bin+44
end=bin+65535-44
FOR J=start TO end
RR=RANDOM(32767)
PRINT RR
POKE J,RR
NEXT

PUTBYTE bin TO myfile SIZE 65535

CLOSE FILE myfile


Note that on one page I linked to above the offset at 28 is called "bytes/second" and says "sample rate * block align". On the other page I found it described as "Byterate" and "SampleRate * NumChannels * BitsPerSample/8", that's the one I used. Same for the next one "Blockalign" too.

That program will create a wav file (noise) as I found some useful infos here ( www.lightlink.com/tjweber/StripWav/Canon.html also ccrma.stanford.edu/courses/422/projects/WaveFormat/ ) . I had imagined the wav file format to be a lot more complex than this!

Only other problems were being able to convert long and normal integers into bytes. For 4 byte integers ("longs") I had to temporarily revert back to dosbox/qbasic and use (uh oh) qbasic's MKL$ command. I came up with this to work out the values for byterate and blockalign;


REM test
CLS

REM Work out the values for Byterate and Blockalign on WAV files.

REM Samplerate (e.g. 44100)
samplerate = 44100

REM Number of channels (1=mono,2=stereo)
numchannels = 1

REM Bits used per sample (8 or 16)
bitspersample = 16

byterate = samplerate * numchannels * bitspersample / 8
Blockalign = numchannels * bitspersample / 8

A$ = MKL$(byterate)

PRINT "Byterate="; byterate
FOR A = 1 TO LEN(A$)
B$ = MID$(A$, A, 1)
PRINT ASC(B$);
NEXT

PRINT
PRINT
PRINT "Blockalign="; Blockalign

HI = INT(Blockalign / 256)
LO = Blockalign - HI * 256
PRINT LO,HI


This helped (qbasic x.x) to convert long integers to bytes;

b=65535
a$=mkl$(b)
for t=1 to len(a$)
b$=mid$(a$,t,1)
print asc(b$);
next


Or integer to byte;

x=2
hi=int(x/256)
lo=x-hi*256
print lo,hi


So ..... far I'm a little further along!

The next problem? Working out how to deal with signed integers (-32767 to 32768) in the data!

.....You see from what I can gather I can't use signed integers in bacon's memory commands so I need to go from signed toi unsigned (and back).

ljones

[ljones]

Just a little further on. The following modification seemed to provide a relatively good sine wave - as a test.

This first line goes at the top;

GLOBAL s TYPE float


And then this replaces the "random" part of the code;

s=0

FOR J=start TO end STEP 2
s=s+0.1
RR=150+22000*SIN(s/8)
HI=INT(RR/256)
LO=RR-HI*256
PRINT RR;
PRINT " ";
PRINT s
POKE J,LO
POKE J+1,HI
NEXT


Should write a reasonably good sine wave into a wav file. It plays as a very low-pitched sound. At this stage I'm not sure if I need to make what I've written into memory above (poke j,lo etc) a signed integer or not.

ljones

[ljones]

unfortunatly I'm possibly going to have to forget the idea.

Here's what I got so far though it dosen't work. Really I don't know enough to do this.


PRINT "Opening 1.ppm"
OPEN "1.ppm" FOR READING AS myfile1

PRINT "Opening test.wav"
OPEN "test.wav" FOR WRITING AS mywavfile

FUNCTION MKL$(NUMBER value)
C1=POW(2,24)
C2=POW(2,16)
C3=POW(2,8)
byte1=value / C1 & 255
byte2=value / C2 & 255
byte3=value / C3 & 255
byte4=value & 255
a1$=CHR$(byte4)
a2$=CHR$(byte3)
a3$=CHR$(byte2)
a4$=CHR$(byte1)
a5$=CONCAT$(a1$,a2$,a3$,a4$)
RETURN a5$
END FUNCTION



PRINT "Counting bytes"
REM count the bytes
READLN i1$ FROM myfile1
READLN i2$ FROM myfile1
READLN i3$ FROM myfile1
READLN i4$ FROM myfile1
A=INSTR(i3$," ")
x$=MID$(i3$,1,A-1)
y$=MID$(i3$,A+1,LEN(i3$))
xsize=VAL(x$)
ysize=VAL(y$)
FOR y=1 TO ysize
FOR x=1 TO xsize
b1=MEMORY(1)
GETBYTE b1 FROM myfile1 SIZE 1
red=PEEK(b1)
b2=MEMORY(1)
GETBYTE b2 FROM myfile1 SIZE 1
green=PEEK(b2)
b3=MEMORY(1)
GETBYTE b3 FROM myfile1 SIZE 1
blue=PEEK(b3)
FREE b1
FREE b2
FREE b3
filesize=filesize+6
NEXT
NEXT
CLOSE FILE myfile1

PRINT "The filesize is in bytes ";
PRINT filesize

PRINT "Allocate memory"
bin=MEMORY(filesize)

DATA 82,73,70,70
DATA 0,0,0,0
DATA 87,65,86,69
DATA 102,109,116,32
DATA 16,0,0,0
DATA 1,0
DATA 1,0
DATA 68,172,0,0
DATA 136,88,1,0
DATA 2,0
DATA 16,0
DATA 68,65,84,65
DATA 0,0,0,0

PRINT "Poking 43 byte wav header"
FOR count=0 TO 43
READ data
POKE bin+count,data
PRINT "Byte ";
PRINT count;
PRINT " ";
NEXT count

PRINT
PRINT

PRINT "filesize1/2"
filesize1=filesize-8
filesize2=filesize-43

PRINT "Poking file length"
REM file length-8
A$=MKL$(filesize1)
FOR J=1 TO 4
B$=MID$(A$,J,1)
POKE bin+3+J,ASC(B$)
PRINT J;
PRINT " ";
PRINT bin+3+J
NEXT J

PRINT

PRINT "poking file length (2)"
REM filelength-44
A$=MKL$(filesize2)
FOR J=1 TO 4
B$=MID$(A$,J,1)
POKE bin+39+J,ASC(B$)
PRINT J;
PRINT " ";
PRINT bin+3+J
NEXT J

PRINT

start=bin+44

PRINT "Poking wave data now=";
PRINT start
PRINT

REM Poke data
OPEN "1.ppm" FOR READING AS myfile1
READLN i1$ FROM myfile1
READLN i2$ FROM myfile1
READLN i3$ FROM myfile1
READLN i4$ FROM myfile1
A=INSTR(i3$," ")
x$=MID$(i3$,1,A-1)
y$=MID$(i3$,A+1,LEN(i3$))
xsize=VAL(x$)
ysize=VAL(y$)

FOR y=1 TO ysize
FOR x=1 TO xsize
b1=MEMORY(1)
GETBYTE b1 FROM myfile1 SIZE 1

red=PEEK(b1)
hi=INT(red/256)
lo=red-hi*256
POKE start,lo
POKE start+1,hi
start=start+2

b2=MEMORY(1)
GETBYTE b2 FROM myfile1 SIZE 1

green=PEEK(b2)
hi=INT(green/256)
lo=green-hi*256
POKE start,lo
POKE start+1,hi
start=start+2

b3=MEMORY(1)
GETBYTE b3 FROM myfile1 SIZE 1
blue=PEEK(b3)

hi=INT(blue/256)
lo=blue-hi*256
POKE start,lo
POKE start+1,hi
start=start+2

FREE b1
FREE b2
FREE b3
NEXT
NEXT

PRINT "Closing file"
CLOSE FILE myfile1

PRINT "Write data"
PUTBYTE bin TO mywavfile SIZE filesize
CLOSE FILE mywavfile

PRINT "filesize is"
PRINT filesize


Half the problem is the original is in perl and uses perl modules and I'm basically having to reimplement half of perl or so it seems. Ah well. .

I did see something called libsndfile though I have no idea on how to use it.

ljones

[Pjot]

and I'm basically having to reimplement half of perl or so it seems

Well, that is not completely untrue...

BaCon is just starting and a lot of interfaces need to be developed. If you want to volunteer, go ahead

Thanks for your efforts so far!

Regards
Peter