Recording your phonograph records digitally (was: Play wav files from serial input)

[Bill Freeman]

Charles Farinella writes:
 > On Wed, 2005-01-12 at 15:11, Bill Freeman wrote:
 > 
 > > (I'd been happily converting records to digital until
 > > my laptop died last year.)
 > 
 > I've been wanting to do that for awhile, but haven't been able to
 > motivate myself enough to figure out how.  Tips?  Brief rundown?

	I was using "rec", also from sox.  I'm sure that there are GUI
solutions as well.  I have a cable (from Radio Shack) with a mineature
stereo phone plug on one end (fits the sound card line in jack), and a
pair of RCA phono plugs on the other end (fits the tape out or
tape-rec jacks on the HiFi amplifier/receiver) (no attenuation).

	I'd have the rec command all typed, but for the carriage
return, drop the needle in the lead in area, and hit enter.  At the
end of the cut, hit control-C.

	That generally left me with some silence at each end, but there
are sox commands that you can use to trim time from the beginning and
end of a cut, so you can get pretty tight tracks.

	Sox will give you an idea of whether your samples come close
to the maximum levels, which is sort of like watching the VU meter on
a tape recorder, to see if the record level is good.  You do want to
have the peaks of the music fairly close to the limits, so that the
noise floor is as far away as possible.  Sox is willing to adjust the
samples, but this looses information, so its best to have the basic
recording give you a good record level.

	Sadly, the volume control on your amplifier doesn't affect the
line level outputs.  (That's why your tape deck has a "record level"
knob.)  The sound card will have a "mixer" that you can use to adjust
the analog level of the line in connection.  It may be possible to set
the mixer with a command line tool, maybe even with an option to rec,
but I just used the GUI mixer that was installed on my box (IIRC).

	Rec has a mess of options, and you will want to set them
according to your usage.  For example, if you're going to master a CD,
you should probably use the same sampling rate that CD players use
(44,100 samples per second, if I'm not mistaken).  There are things
like number of channels, bits per sample, and some other format stuff.
(Probably ripping a track from a commercial CD and doing "file" on the
resultant wav file will give you some insignt.)  The sox documentation
is significant, but last I checked, lacking in a "you probably want
this" section.  If it turns out to be a problem, I can find some old
backups of the laptop and see what options I was using.

	Sox can also do format conversions, time resampling (speed
up/slow down the "tape"), pitch change (without speed change), speed
change (without pitch change), and filtering to remove hiss, clicks,
and pops.  It is, however, a command line tool, so you have to read
the man pages and compose a set of switches.  OTOH, once you've
figured out how to perform an operation, if you want to do it to a
bunch of tracks, you can write a script, and Bob's your uncle.

							Bill