[lug] sound recording roadblocks and solutions

D. Stimits stimits at idcomm.com
Tue Sep 5 21:28:13 MDT 2000

Neal McBurnett wrote:
> I'm amazed at how hard it has been to find a way to record audio
> in linux.  So I started writing a question to the lug.  As
> so often happens, the process of writing good questions resulted
> in figuring out most of the answers I was looking for.
> I'm currently running redhat 6.1.  [Yeah, I'll upgrade to 6.2
> when I free up some disk space - sigh]
> The sound howto says to just cat /dev/audio to a file.  This
> results in files that are very small, and which can be played back by
> catting back to /dev/audio, but which other recommended tools (see
> below) can't seem to handle at all.  I can't figure out what
> the sampling rate or bits/sample are, they seem to be even less that
> 8000 Hz, 8 bits/sample.

8 bits/sample is resolution. 8 bits will give good quality, but maybe
not what you want if you are working with good music.

8000 Hz is the sample rate...how often those 8 bits are sampled.
Generally, I think both the bits/sample and sample rate must be matched
if you are mixing sounds.

> The sound howto (March 1999) also suggests a tool called "vrec" which
> is not part of my redhat 6.1 system.  No package of that name is
> visible anywhere and we searches with google haven't led me to any
> code (just some old man pages), so I'm guessing it is in some other
> package or is obsolete.

Found this link, and snippet:
For editing/recording sound
  vrec       -- link to vplay

Apparently vrec is just a symbolic link to vplay.

This leads to:

Which leads to:
vplay and vrec are available  via  anonymous  ftp  in  the
      PCSP-Sounddriver  package from ftp.informatik.hu-berlin.de

The directory they gave is out of date, the final URL for the package

Let me know if it is any good...I might be interested in it later.

> Downloading krecord sends me on another unsuccessful search for
> libstdc++-libc6.1-2.so.3.

This comes with C++. Do you have g++ (try "which g++")? Probably the lib
is in:
possibly with a minor variation of name. My RH 6.2 is

> Ah - so the sound howto is out of date - clearly.  Yeah - I know,
> keeping things up to date is a pain, and I do appreciate all the good
> stuff in there....  Perhaps copying this to the maintainer will help.
> Thankfully, a more up-to-date faq with relevant info is the mp3 howto.
>         http://metalab.unc.edu/mdw/HOWTO/MP3-HOWTO.html
> This, along with my experimentation, suggests that the good tools are
> rawrec or wavplay/wavrec for getting input from the hardware in WAV
> format, lame (for creating mp3's from .wav files), and aumix (for
> setting record and playback volumes and balance.  Aumix is more
> capable and flexible than xmixer).  Wavrec and xmixer are part of my
> redhat distribution.
> Lame is much faster than bladeenc and doesn't have problems with
> mono inputs.
> So this works well for recording a mono input to my "line in"
> and putting it in file.mp3:
>         rawrec -c 1 | lame -x -m m - file.mp3
> and this should do the stereo case:
>         rawrec | lame -x - file.mp3
> The lame encoding records at about twice real-time at this speed
> on my pentium 266, so this works great.  And it results in about
> 1/2 MB/minute, producing good audio quality, which isn't bad at all.
> Waverec really really wants to write to a file, and even a pipe
> doesn't work (it tries to seek on it for some odd reason).  I
> didn't need the "-x" option to lame when using wavrec.
> Hopefully this will help someone out there....
> Cheers,
> Neal McBurnett <neal at bcn.boulder.co.us>  303-538-4852
> Avaya Communication / Internet2 / Bell Labs / Lucent Technologies
> http://bcn.boulder.co.us/~neal/      (with PGP key)
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