# 40gb: How much record time?

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That would depend on the sampling rate.

<ntt4don@nttworldwide.com> wrote in message
> They say dozens of tracks but if recording non-stop such as a radio
> talk show, how much record time can you get?
>
Anonymous

ntt4don@nttworldwide.com wrote:
> They say dozens of tracks but if recording non-stop such as a radio
> talk show, how much record time can you get?

Since the only clue you gave was "radio talk show", I will assume
you want to record two tracks (b/c the radio program is stereo) and
you want to record at 44.1 kHz sampling rate and 16-bit sample size.

The math is pretty simple. There are 44100 samples taken per second
per channel. Since a sample is 2 bytes and there are 2 channels,
that means 2 * 2 * 44100 bytes needed per second, plus any overhead,
of which there is virtually none. This means about 176 kilobytes
per second, and since there are 3600 seconds in an hour (and there
are 1024 * 1024 kilobytes in a megabyte), that means about 0.605
gigabytes per hour.

So, 40 gigabytes, that'd be about 40 / 0.6 == 66 hours.

If you use a higher sampling rate or larger sample sizes, you can just
multiply by the appropriate factor to adjust. For example, 24-bit
instead of 16-bit samples would mean you are using 50% more space,
so you need to multiply your capacity in hours by 2/3, giving 44 hours.
If you switch to 96 kHz instead of 44.1 kHz, you need to multiply your
capacity in hours by 44.1/96, so if you are doing 96 kHz and 24-bit,

- Logan
Anonymous

"Logan Shaw" <lshaw-usenet@austin.rr.com> wrote in message
> ntt4don@nttworldwide.com wrote:
>> They say dozens of tracks but if recording non-stop such as a radio
>> talk show, how much record time can you get?
>
> Since the only clue you gave was "radio talk show", I will assume
> you want to record two tracks (b/c the radio program is stereo) and
> you want to record at 44.1 kHz sampling rate and 16-bit sample size.
>
> The math is pretty simple. There are 44100 samples taken per second
> per channel. Since a sample is 2 bytes and there are 2 channels,
> that means 2 * 2 * 44100 bytes needed per second, plus any overhead,
> of which there is virtually none. This means about 176 kilobytes
> per second, and since there are 3600 seconds in an hour (and there
> are 1024 * 1024 kilobytes in a megabyte), that means about 0.605
> gigabytes per hour.
>
> So, 40 gigabytes, that'd be about 40 / 0.6 == 66 hours.
>
> If you use a higher sampling rate or larger sample sizes, you can just
> multiply by the appropriate factor to adjust. For example, 24-bit
> instead of 16-bit samples would mean you are using 50% more space,
> so you need to multiply your capacity in hours by 2/3, giving 44 hours.
> If you switch to 96 kHz instead of 44.1 kHz, you need to multiply your
> capacity in hours by 44.1/96, so if you are doing 96 kHz and 24-bit,
>
> - Logan

In addition, keep in mind that different operating systems ( and audio apps
too I guess ) have a file size limitations. Many are limited to 2 GB max so
using Logan's numbers above ( 0.605 gigabytes per hour ) and if your
system maxes out at a 2 GB file size you'll only be able to record about 3
hours and 20 minutes before your app stops or crashes ( or seems like it's
still working but you get nothing ). I think there are ways around this but
I never had a need for it.

John L Rice
Related ressources
Anonymous

And the bit depth. And how many channels. Or if it's compressed.
FWIW, my 40GB recorder holds over 60 hours of CD quality stereo audio.

In article <_9ednQ8AyuW-O-TfRVn-og@comcast.com>, Rob <rob@hotmail.com> wrote:
>That would depend on the sampling rate.
>
><ntt4don@nttworldwide.com> wrote in message
>> They say dozens of tracks but if recording non-stop such as a radio
>> talk show, how much record time can you get?
>>
>
>
Anonymous

Quick reminder: For marketing purposes, disks are measured in
metric/decimal metric multipliers, not in computerese -- a kilobyte of
disk really is 1000 bytes, not 1024; a megabyte is a million bytes, and
so on.

From that, subtract whatever overhead the formatting and filesystem
imposes.

Its still going to be in the same general ballpark, but if you're trying
to calculate real numbers you need to allow for these.
Anonymous

I've been looking at the Tascam 2488 for demo-ing our 1 hour radio talk
show. Seems over kill for this purpose but mutliple tracks and storage
capacity and ability to burn CD are all attractive features. In
addition I don't think we would be needing all the effects provided on
the 2488. Seems like a lot of what we would be doing could be computer
based/generated but I like the controls and access of a digital
recorder.

Any over suggestions on a mixer/recorder/cd combo for a talk show and
not necessarily for recording music would be appreciated.
Anonymous

> So, 40 gigabytes, that'd be about 40 / 0.6 == 66 hours.

I remember 11 megabytes per minute from DAT days. Close enough for
jazz. Once you know one number, until you get into data compression
schemes (which give you an ambiguous amount of data reduction, and
hence increase in recording time) everything is just a linear ratio.
Double the sample rate, you halve the recording time. Increase the
word length by 1.5 (to 24 bits) and you decrease the recording time by
1.5.

But given that it's a radio program, a sample rate higher than
44.1 kHz wouldn't make any sense. If transfer to an audio CD isn't a
concern, a lower sample rate (32 kHz, for instance) would be OK,
though I'd stick with 16-bit resolution just on general principles.

I record a 6 hour overnight bluegrass radio program using 192 kbcs MP3
compression with a version of the LAME encoder, stereo, 44.1 kHz, and
it comes out to be a bit more than 500 megabytes.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous

On Thu, 5 May 2005 04:56:37 +0000 (UTC), louie@u.washington.edu (G.
Louie) wrote:

>And the bit depth. And how many channels. Or if it's compressed.
>FWIW, my 40GB recorder holds over 60 hours of CD quality stereo audio.

It's a simple math question (drive size in gigabytes / (4 bytes per
sample * 44,100 samples/second)), but we're all too lazy to work it
out for the OP.

Since he's recording radio, that may be a good answer. OTOH, for
talk radio where full CD quality isn't needed, you can get away with
making it mono, 8-bit, 22ksps, each of which doubles the recording
time over the CD data rate, and the combination gives 480 hours
recording time. You can get even more recording time using
psychoacoustic data compression, but the 'underwater' sound is a lot
more bothersome to me than cutting off at 10kHz.

>In article <_9ednQ8AyuW-O-TfRVn-og@comcast.com>, Rob <rob@hotmail.com> wrote:
>>That would depend on the sampling rate.
>>
>><ntt4don@nttworldwide.com> wrote in message