OK, I'll chime in here.
Shai Drori mentioned that he has been digitizing at 24Bit/48kHz. Shai
also mentioned that the bandwidth stops at about 3Khz. At a 48kHz sample
rate, 3kHz gets sampled 16 times per second. IMHO, I would stay with
24/48. I'm currently working with some compact cassettes that were
recorded at half speed (15/16 IPS) and the bandwidth on those tapes
stops at around 5kHz. However, the format, running at that speed is
capable of about 8kHz. So, some of the 40 track tapes that Shai is
digitizing may indeed have a bandwidth that exceeds 3kHz.
FYI: I digitize creating two files at once. In the case of the
aforementioned tapes that I'm working with, I'm creating 44.1kHz and
96kHz files, all at 32 Bit float. I don't have anywhere near the file
issues that Shai has with his project so I can get away with a higher
Corey Bailey Audio Engineering
On 7/12/2017 6:51 PM, Tim Gillett wrote:
> Hi Shai,
> No replies so far to the specific question so here goes. Yes given the
> source I'd have no problem reducing down to 22kHz or even 11
> uncompressed. I would have thought MP3 at 256 kB/s (mono) would be
> more than adequate too. It seems unlikely either would be anywhere
> near compromising the original quality.
> I take it that if the source noise floor is not compromised in the
> file compression process, then by definition everything else will be
> fine also. With MP3 type compression though, if it's set at too low a
> bitrate, tape dropouts can become exaggerated, (eg: many YT uploads )
> so just to be safe I'd go for an MP3 rate to avoid that.
> At 15/32 ips azimuth alignment must be fairly critical. Out of
> curiosity how wide is the 40 track tape?
> Tim Gillett
> Western Australia
> ----- Original Message ----- From: "Shai Drori" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Sunday, July 09, 2017 2:19 PM
> Subject: [ARSCLIST] Small file formats
> Hi Gang
> Seeing the wisdom of the group. I am digitizing log tapes for a client.
> Tapes are 40 tracks each generating 400GB per tape at 48kh/24bit.
> there is nothing on those 15/32" IPS tapes that needs that fidielity, and
> my client doesn't have the storage capacity for all her tapes (lot of
> them). So the question is what format should we compress to. MP3 at
> is one option, staying with wave but reducing the sampling to 22Khz/16bit
> is another (not sure it's small enough), maybe even 11Khz? Other options?
> As you can imagine the audio is worse than AM but I do want to keep it as
> close to the original as possible. Manufacturer claims top freq at around
> שי דרורי.
> מומחה לשימור ודיגיטציה של אודיו וידאו ופילם 8-35ממ
> Shai Drori
> Expert digitization services for Audio Video
> Hi Res scanning for film 8mm-35mm
> Timeless Recordings Music Label
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