[bookport] Re: A Step-by-Step Guide For Converting four-track half-speed cassette-based Data to MP3 Digi

  • From: "MICHAEL MCCARTY" <mmccarty@xxxxxxx>
  • To: <bookport@xxxxxxxxxxxxx>
  • Date: Fri, 15 Jul 2005 15:07:36 -0400

Nolan,

Could I use your overview of turning a four-track cassette in to an MP3
in Fred's Head?  I'd love this information to appear in our database. 
You will receive full credit for the article of course.
 
Michael McCarty

An Overview:

This mini tutorial will provide the steps necessary for converting data
from
a four-track half-speed cassette to MP3 files used by the Book Port. 
None
of the steps here are screen reader specific, but all of the steps
assume
that you have Sound Forge, and this was written on the basis of Sound
Forge
8.0.

WHAT YOU NEED:

You'll need a stereo cassette player capable of playing both channels
of a
stereo cassette at the regular 1-7/8 Inches Per Second speed at least. 
If
you have a dubbing deck that can move the tape at an even faster rate,
that's even better, provided the dubbing signal can travel from the
deck
into your computer's sound card.  You'll also need a half-speed
four-track
cassette recording such as Newsweek or the Reader's Digest, both
available
from the American Printing House for the Blind.  You'll need the
appropriate
cords to connect your tape deck or handicassette machine to your
computer's
sound card.  You'll need a computer with a sound card capable of
receiving a
line in signal.  I'm using a Live Value card from Creative Labs.  Prior
to
completing these steps, you'll need to create a 24 kilobits per second
MP3
template in Sound Forge.  You may want to opt for 24 KBPS and mono
rather
than stereo recording when you create this template.  The creation of
such a
template is outside the scope of this document, but virtually every
version
of Sound Forge from 5 to 8, and probably earlier, is capable of
creating a
24-KBPS mono MP3 file template.  This is important because it's what
you
will use when you save the final product we convert from the cassette.
Also, make sure you've gone into the record options of your volume
control
and that you've checked your line-in volume to be one of the volume
controls
shown in the volume control settings of your computer.  I do this by
running
a program called sndvol32, which can be found on your computer.  Again,
the
details for doing this are outside the scope of this document.  By
selecting
the line in volume, you ensure that you will be able to hear a signal
if you
wish to do that.

For the purposes of this little mini guide, I'll assume that you're
using a
stereo cassette machine capable only of playing tapes at the standard
speed.

THE STEPS:

1.  Insert your four-track tape into the cassette machine, making sure
the
machine can play both stereo channels at once and that it is set at the
high
or standard speed of 1-7/8 IPS.  Cue the cassette the old-fashioned
way--by
rapidly finding the beginning of the voice track, stopping the tape
immediately at the beginning, then removing the cassette and rewinding
it
slightly with your finger, re-inserting the cassette, putting the
pause
control on, and activating the play button.

2.  Make sure your cords are properly connected between the cassette
unit
and your computer's sound card.

3.  Open Sound Forge

4.  Activate the record preparation control in Sound Forge with
Control+R.
When you check your record attributes, make certain that you're
sampling at
44,100 Hz. and that the stereo channel radio button is selected.  You
can do
that by tapping the Alt+C key combination, then moving through the
radio
button selections with your arrow keys.  You have only two selections
here--mono and stereo.  Make sure you've selected stereo.  The sampling
rate
designation is a combo box, so your Up and Down Arrow keys should let
you
see your choices.  Make certain 44,100 Hz. is selected.

5.  Simultaneously do an Alt+R key combination to start the recording
and
release the pause button on your player.  The Time Recorded information
in
Sound Forge should begin to show the number of seconds and eventually
minutes and seconds the machine is recording, and you should hear the
signal
through your computer speakers.

6.  At the conclusion of the recording, between 30 and 45 minutes from
when
you start, depending on whether you're converting a magazine or
full-fledged
book, do an Alt+F4 to terminate the recording.  You should now have
two
tracks recorded on your hard drive--track one, which will sound normal
except for the double speed component that will give it a chipmunk
effect,
and track four, which will sound reversed.  Please remember when
you're
using a stereo machine to convert four-track half-speed cassettes, the
braille side of the cassette will include tracks one and four while
the
non-braille side will include tracks two and three.  Since we recorded
the
tape with the braille side up, we're working on tracks one and four.

7.  Do a Control+Home key combination to move to the top of your
recorded
file and tap Spacebar to hear the beginning to make sure it sounds
relatively ok so far.  Remember, you should be hearing both tracks
with
voices that sound like a speeded up cassette.  You may not hear track
four
immediately at the same time you hear track one.  This is because of
the
mastering process.  Eventually, however, you'll hear track four nice
and
loud and backwards.

8.  Activate only the channel that includes the reverse track four. 
For me,
it's my right channel, so I would tap the Tab key twice--once to
activate
only the left channel and again to activate only the right one. 
Whatever it
takes, this right channel must be the one you hear when you tap the
Spacebar.

9.  With the reverse track four channel activated, open the Process
menu
with Alt+P and activate the mute channel menu item by simply tapping
M.
After a few seconds of processing time, the reverse track channel,
again for
me the right channel, is muted entirely.

10.  Tap your Tab key two times to activate the relatively
normal-sounding
track, track 1, and tap your Spacebar just to make sure that's the one
you
have activated.  

11.  Now execute a Control+A key combination to select all the audio in
the
channel from the beginning to the end.  Then do a Control+C key
combination
to copy the selected material to the clipboard.

12.  Open a new sound window with Control+N and make absolutely sure
you do
the two following actions.  Failure to do either of these could result
in a
less-than-successful outcome.
A.  In the sample rate combo box that comes up first thing when you
open a
new sound window, up arrow until you have selected 22.050 Hz. as your
new
sampling rate.  Notice this is exactly half of the sampling rate you
used
when you created the original recording.
B.  Change the channel selection radio button from stereo to mono with
Alt+C
then Up Arrow to Mono.  Tap Enter to accept the new settings.

13.  Paste the text you selected earlier into this new window with
Control+V.  When you do, a dialogue opens, asking if you're sure you
want to
do this, since the resampling will alter the pitch of the voices. 
Activate
the Yes button, and the paste process will go forward from there.

14.  You're almost ready to save this as an MP3 file.  But if you're a
bit
of a perfectionist, as I am when it comes to this audio stuff, you'll
want
to trim the ends and possibly get rid of the unnecessary instructions
about
turning the cassette over and such.  I do leave the side designations
in mbo box, so your Up and Down Arrow k
place as well as the table of contents material if it exists.  Just use
your
Sound Forge editing commands to trim the ends to your liking.

15.  Open the Save File dialogue (Control+S) and make sure the 24 KBPS
template you created earlier is selected.  Give the file an appropriate
file
name with an MP3 extension, make certain the file will go to a
directory
where your Book Port transfer software can easily find it, and activate
the
Save button.

16.  Close the sound window; you no longer need this one open.  When
you
close the window, (Control+W works nicely for that), you'll be asked to
save
changes.  You already have saved the file, so opt for the no button at
that
point, and the window is closed and you're back in your original
chipmunk-sounding recording with the track four reverse channel still
muted
out.

17.  It's time to restore the channel you muted earlier.  Do a
Control+Z key
combination or open the Edit menu and select the undo option--either
way.
After a few seconds, tap the Spacebar to ensure that your reverse track
four
channel is indeed back.

18.  Now it's time to mute out the track one normal-sounding (left)
channel
that you've already saved as an MP3 file.  Tap Tab twice to activate
that
channel and make it the dominant one.  If you only tap Tab once, you'll
get
both channels evenly.  With the normal-sounding channel now the
dominant
one, open the processes menu, (Alt+P), and activate the mute command
by
tapping M.  

19.  Tap Tab once to make the reverse track four the dominant channel
again.
You'll be working with this channel for the rest of the time.

20.  Select the entire contents of this channel with Control+A then
copy the
contents to the clipboard (Control+C)

21.  Open a new sound window (Control+N), and remember that it will be
unchanged from the other sound window you opened earlier in order to
save
track one.  In other words, this new window will also include a
sampling
rate of 22,050 Hz. and the channel selection will still be mono.  Tap
Enter
to accept these settings.

22.  Now paste the contents of the clipboard into the new sound window
you've just opened.  Again, the dialogue will open, appointing out
that
you're about to alter the pitch of your data.  Simply activate the yes
button and the paste will commence.

23.  Now that the channel is pasted, open the processes menu (Alt+P)
and
activate the reverse process with R.  After a few seconds, your track
four
will sound normal in pitch and certainly normal in terms of the
content.

24.  Because of the mastering process, this track will almost
inevitably
have lots of space at one end or another that you can trim.  This is
the
point at which you trim the ends if you want to.

25.  Save this channel now as the second MP3 file.  I usually call it
by the
magazine or book name and then delineate track 4.  So it might say,
Newsweek
July 4 track 4.mp3.

26.  Now close this sound window; you no longer need it once the file
is
saved.

27.  Now close the window that contained the original
chipmunk-sounding
tracks.  You don't need to save it for any reason, so simply activate
the no
button when Sound Forge points out that the file is changed but not
saved.

28.  Now it's time to clean up after yourself a bit.  By that, I mean
that
you need to restore your sampling rate and channel selection settings
in
preparation for recording the non-braille side of the cassette.  To do
that,
open a new sound window with Control+N and down arrow in the sample
rate
combo box until you again hear 44,100 Hz.  Also, give focus to the
channel
selection radio buttons (Alt+C) and down arrow until stereo is
selected,
then tap Enter to accept the settings.  This is an extremely important
part
of the process.  It's too easy to just close Sound Forge and think
you'll
fix that part later, only to start a recording later having forgotten
to do
this fix.

29.  Insert the cassette braille side down into your machine, cue it,
and
repeat steps 4 to 29.

Congratulations!  You've successfully completed your four-track
conversion.

Nolan Crabb




Michael McCarty
Fred's Head Database Coordinator
American Printing House for the Blind
Phone: 502 895-2405
Fax: 502 899-2363
www.aph.org

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  • » [bookport] Re: A Step-by-Step Guide For Converting four-track half-speed cassette-based Data to MP3 Digi