Subject: Re: [linux-audio-user] live recording on a laptop
From: Jörn Nettingsmeier (nettings_AT_folkwang-hochschule.de)
Date: Thu Dec 20 2001 - 02:15:37 EET
Chris Majewski wrote:
>
> Folks
> I've borrowed a laptop to do some live recording on. It's a generic
> AMD K-2 300 MHz machine with Yamaha OPL3-SA2 on-board sound. I rented
> a pair of decent condenser mics and a powered mixer from the local
> music shop, and made some recordings of my jazz combo which worked
> pretty well. Meanwhile, millions of questions..
>
> - Is this soundcard any good? Would there be a noticeable difference
> with a $1000 pro-quality soundcard?
ooh yeah there will !
>Or is the bottleneck somewhere
> else, e.g. electrical noise from the laptop?
this is also a problem. the best solution for laptops are these
little pcmcia thingies with an external connector and converter box,
like the upcoming hammerfall dsp.
> - Which software to use for recording? So far I've been using the ALSA
> drivers and recording with either 'arecord -w -m' or 'ecasound -c -b:128
> -f:16,2,44100 -a:1 -i /dev/dsp'. I also tried 'arecord -w -M' (48 kHz)
> and that worked. One advantage of these two is that they don't need X,
> so I can boot in text mode only (I'm more of a kbd guy than a mouse
> guy).
i use arecord most of the time, too.
> A disadvantage is that I haven't figured out how to monitor what
> I'm recording, the way you can on a tape deck. In fact, the minute I
> start recording, I don't hear anything in my headphones other than a
> faint clicking sound.
try issuing aplay <yourfile.wav> on another console. latency will be
the time between record and playback start. works well for me, but
this will probably depend on the full-duplex behaviour of your sound
hardware.
> The recording turns out fine when I play it
> back, though. Same thing when I run the mixer (aumix or alsamixer):
> the line input signal goes away, or plays intermittently. I have to
> play a .wav file to revive it. Is this a "feature" of the OPL3-SA2?
dunno.
> - One thing I've discovered is "ecasignalview", which roughly tells me
> if I have any clipped samples. Are clipped samples really bad?
ooooh yes !
> I mean,
> is it OK to have a few of them?
for practical use, three consecutive maximum samples are considered
"clipping" and will result in audible clicks. more will sound worse.
i'd say avoid clipping at all costs. it's a major headache to work
around when mastering.
in live situations, ride the gain *very conservatively*. 15db
headroom is not too much.
also, when looking at meters, keep in mind that most of them are too
slow for digital signals, so even though your peak meter is well
below 100%, there may be very short clips. only last weekend i
recorded a jazz guitarist on an adat xt, and even though the meters
were clean, we found some clips on the tape during mixdown.
> Other than that ecasignalview is
> confusing and weird, so if there's anyone else out there using it,
> maybe you can give me some tips.. for instance, how can I turn off the
> cumulative statistics, and display statistics on a rotating
> fixed-length sample instead (e.g., the last two seconds)?
>
> - If I get serious about this, and decide to buy my own laptop, what
> criteria should I look at?
if you've got a high budget and want to go professional, i'd say buy
an apple g4 powerbook and get one of the hammerfall dsps. paul d.
has announced he will start writing a driver in january.
my girlfriend has a g3 'book which i have the pleasure to
administrate. these are really well-designed, fast and good-looking
machines with low power consumption - with 2 batteries, the g3
lasts well over 8 hours.
maybe others can comment on other options with decent built-in
sound.
regards,
jörn
-- Jörn Nettingsmeier home://Kurfürstenstr.49.45138.Essen.Germany phone://+49.201.491621 http://spunk.dnsalias.org http://www.linuxdj.com/audio/lad/
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