Re: [ARSCLIST] National Recording Preservation Board (NRPB) Study

[Mike Richter <mrichter@xxxxxxx>]

steven c wrote:

> I have about 80,000 78 sides to (eventually) archive in digital form.
> As moderate-quality MP3 files of, say, 500KB each...I would need
> about 40,000MB...or 40GB, which I could store on a single not-too-
> expensive drive. Wav files would be (I think) about 20 times the
> size, or .8TB (for I don't know how much...).

The numbers are easy enough and probably worth sharing here.

Redbook WAV (two channels, 16 bit depth, 44.1 ksps, PCM) is about 10 
MB/minute. Minimum quality suggested is usually one channel, 16 bits, 
22.05 ksps for 2.5 MB/minute. (In practice, 10-12 bit depth would 
suffice, but I know no software for that; 8 bits is pushing it.)

Lossless compression is more effective on quiet material than on noisy, 
so you can't count on more than 40% reduction.

The usual compression for MP3 is about 11:1. Good recognition is 
achieved from 78s at 32 Kbps (22.05 ksps, monaural) which means four 
minutes per MB. On average, a 78 side is likely to run 3-3.5 minutes - 
so be a pessimist and say 4 minutes. 80,000 sides would then be around 
80 GB in 32 Kbps MP3 up to 3.2 TB in redbook WAV or equivalent (e.g., 32 
bits depth but single channel). Go to archival extremes such as two 
channels, 96 ksps, 32 bits, PCM and you're looking at 16 TB - not 
impossible today nor even a great fortune, but probably more expensive 
than the benefits for access are worth. (Access is distinguished from 
archival purposes; the cost/benefit analyses differ for those two.)

Mike
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mrichter@xxxxxxx
http://www.mrichter.com/