I'd suggest keeping the bit depth up: 16-bit at minimum. If you think some
"enhancement" is going to be needed: 24-bit. The sample rate probably can
come down.
Steve Greene
Audiovisual Archivist
Nixon Presidential Library and Museum
National Archives and Records Administration
(301) 837-1772
On Wed, Jul 12, 2017 at 11:56 PM, Shai Drori <[log in to unmask]> wrote:
> Hi Corey
> Usually this is not an issue since I allway digitize to WAV files. This is
> a case where we can not keep these files simply because of the size. Each
> tape generates 400 GB of WAV data and there are hundreds of them. We must
> cut down the file sizes.
>
> בברכה,
> שי דרורי.
> מומחה לשימור ודיגיטציה של אודיו וידאו ופילם 8-35ממ
> Cheers
> Shai Drori
> Expert digitization services for Audio Video
> Hi Res scanning for film 8mm-35mm
> Timeless Recordings Music Label
> www.audiovideofilm.com
> [log in to unmask]
> Tripadvisor level 5 contributor, level 10 restaurant expert
>
> On Thu, Jul 13, 2017 at 6:30 AM, Corey Bailey <[log in to unmask]>
> wrote:
>
> > 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 sample rate.
> >
> > My $0.02
> >
> > Corey
> > Corey Bailey Audio Engineering
> > www.baileyzone.net
> >
> > 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
> >>
> >> Perth,
> >> 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.
> >> Obviously
> >> 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
> >> 256KB/s
> >> 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
> >> 3Khz.
> >> בברכה,
> >> שי דרורי.
> >> מומחה לשימור ודיגיטציה של אודיו וידאו ופילם 8-35ממ
> >> Cheers
> >> Shai Drori
> >> Expert digitization services for Audio Video
> >> Hi Res scanning for film 8mm-35mm
> >> Timeless Recordings Music Label
> >> www.audiovideofilm.com
> >> [log in to unmask]
> >> Tripadvisor level 5 contributor, level 10 restaurant expert
> >>
> >> ---
> >> This email has been checked for viruses by Avast antivirus software.
> >> https://www.avast.com/antivirus
> >>
> >>
>
>
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