[FFmpeg-user] Converting a cassette audio tape (Lecture) to mp3

[Luke Davis]

On Sun, 12 Jul 2015, jd1008 wrote:

> No, it is not digitized yet.
>>> I have  plenty of audio tools installed - but not certain what
>>> else I might need.

Personally, I prefer sox for this sort of thing.
Also, arecord would do just as well.

SoX, I believe, has notes in the man page about doing this exact thing, using 
some of its effects.  You might want to try things like noise removal, EQing, or 
other similar stuff, beyond the scope of this list.

If you prefer more of a GUI, Audacity is your friend.

FFMPeg could capture the audio, but this does not seem to be its wheelhouse.

> I have a good (I will not say high) sony tape player with
> stereo audio out (1/4 inch stereo port).
> My laptop is the Dell E6510 with Intel i5 2.67GHz quad,
> and 8GB ram and oodles of swap (embarrassingly 32GB :)  )
> On the laptop, I have the stereo audio in and audio out.

I don't know that laptop in particular, but be careful with all laptops.

Things like HD noise or fan noise, or even charger noise, can get into your 
recording.  By "noise", I mean electromagnetic distortions which effect the 
recording.

Better to use an external USB interface, such as the Behringer UCA202 
<http://www.amazon.com/gp/product/B000KW2YEI/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B000KW2YEI&linkCode=as2&tag=tacticus&linkId=GJKRVWJLP3PUHSLU>.

However, even that will have issues on some laptops.  For example, on some, if 
your battery charger/external power supply is plugged in, all recordings have a 
very bad high pitched multi-frequency noise, with harmonics all over the place 
(I.E. very hard to remove through noise reduction, although possible to get rid 
of somewhat at the cost of audio quality).

I suggest always, no matter what the sound devices involved, doing all laptop 
based recording on battery power, unless you have tested your setup under 
various conditions so that you know how it behaves, and what kind of artifacts 
make it into the end result.  Given the questions you are asking, no offense, 
you likely won't have done that.

Which is not to say don't use laptops--I use them exclusively--just that you 
need to be careful, and listen back with really good headphones.:)

rec -t wav mytape.wav

Might be the most simple command, if all things are setup right.  Even:

rec -t mp3 mytape.mp3

Will work if you have the right libs installed.  Those are the recording 
shorthand commands for SoX.

arecord -D plughw:1 -f cd mytape.wav

Might also do it, presuming you can play around with the device number to find 
the correct one. (Reading the man page and running arecord -L might help).

Both of those can be stopped with ctrl-c, although you can also specify time to 
record for them.

Hth.

Luke (live audio engineer for ~25 years)