Archived from groups: rec.audio.pro (
More info?)
Logan Shaw <lshaw-usenet@austin.rr.com> wrote in message news:<ZF5Sd.18578$cW2.6542@fe2.texas.rr.com>...
> Mike Rivers wrote:
> > In article <b49df8f8.0502200558.675b884b@posting.google.com> st_gf37@hotmail.com writes:
>
> >>Is there any digital recorder, (and by that I mean anyone that records
> >>on a hard disk or RAM memory which could be then loaded on a PC),
> >>which can record continuosly for 2 weeks - non stop?
>
> > All operating systems have some limit to maximum file size. I suppose
> > the first think to look at is how low could you go in quality. If you
> > record at a low sample rate and low resolution, then compress on the
> > fly, you might be able to squeeze two weeks worth of recording into
> > something that an operating system could handle.
>
> Many filesystems these days use 64-bit files. A 32-bit file can be
> 2 GB in size, so a 64-bit one can be about 4 billion times as big as
> that, in other words about 8 million terabytes. That should be enough
> space to record 32 channels of 192 kHz 24-bit for about 31,700 years.
>
> > But I don't have the
> > knowledge or patience to run the numbers. Arny probably does. How bad
> > would it have to be in order to fit a say 170 hours of recording into
> > a gigabyte?
>
> It would be pretty darned bad. That's 1,209,600 seconds, and a gigabyte
> is about a billion, so it leaves just under one kilobyte to record a
> second's worth of audio. So, you can record 1 kHz sampling rate with
> 8 bit samples, 2 kHz sample rate with 4 bit samples, etc., etc.
>
> However, I've heard stuff recorded with 56 kilobit/s MP3 at 22050 Hz,
> and it wasn't atrociously bad. So 56 kilobit is only 7 kilobytes
> per second, which is about one order of magnitude worse than you'd
> need to fit in one gigabyte.
>
> But, that means you should be able to fit it in 10 gigabytes if you
> want relatively low quality. If you go up to 128 kilobit/s MP3, you're
> still only talking about around 20 GB of storage.
>
> So, this is something that could easily be done by a computer. All
> you'd need to do is compress on the fly. That'll probably require
> a relatively fast processor, but the software does exist. You could
> use, for instance, Linux or Unix with lame to do the encoding and some
> command line program (audiorecord on Solaris) to do the recording.
>
> Come to think of it, though, I'm not sure if the MP3 format itself
> can support files bigger than 2 GB. So, you might have to break it
> up, but that's not a big deal. If you were going the command-line
> Unix route, you could do something like this to automatically
> break it up into 500 MB increments:
>
> seqnum=1
> audiorecord -c 1 -s 44100 -e linear |
> while true
> do
> dd ibs=512 count=1000000 of="$seqnum".raw
> touch "$sequnum".raw.done
> seqnum=`expr "$seqnum" + 1`
> done
>
> Then all you've got to do is have an MP3 encoder, like LAME
> for instance, come along behind that and encode every .raw
> file once it sees the corresponding .raw.done file has been
> created.
>
> So, it's kind of ugly and not user-friendly, but it certainly
> can be done.
>
> - Logan
Hi,
Thanks. I know about the possibility of writing to a PC but the
problem is the size. I had a look at the Palms but they do not seem to
have a hard disk. I am not sure if I can connect one externaly.