Subject:Best Sample Rate and Bit Rate for Archiving Tapes?

Posted by: john_dennis

Date:8/16/2009 1:08:24 PM

I'm using Sound Forge 9.0 and a Delta Audiophile 24/96 sound card.
I have more than fifty hours of live stage recordings from my days as a professional musician. These recordings were made from 1969 to 1975 on AKAI consumer grade equipment from the stages where I played. The thrust of this effort was archiving what happened, not commercial release.
I captured some of these tapes in the 90s, made CDs from them and shared them with some of the members of the groups. This was great fun and no profit. Because technology marches on, I have been unwilling to get rid of the tapes or the tape drives. I wonder if I faithfully captured the full quality of the tapes at 44.1 KHz and 16 bit.
I am able to capture them now at 96 KHz and 24 bit WAV and can afford to buy the disks and make backup copies to keep them for posterity.
My question is: Given that the tapes are quarter track stereo and the S/N ratio of the tape drive is in the 55 db range, is it all just a waste of time, money and disk space to record for archiving purposes at greater the 44.1/16?
In the past I have used CD as the delivery option but, in the future, I couldn’t guess how this content might be delivered.
Any technical comments or emotional outbursts are welcome.

John Dennis

Subject:RE: Best Sample Rate and Bit Rate for Archiving Tapes?

Reply by: Geoff_Wood

Date:8/16/2009 1:46:31 PM

No point in anything over 44K1 - there is no program content thre at all.

I guess 'headroom' isn't an issue as your max ouput is well-defined, but still some point in 24 bits though - allows for boosting level of some lower level parts with less degradation. And allows to be more conservative with level setting.
geoff

Subject:RE: Best Sample Rate and Bit Rate for Archiving Tapes?

Reply by: john_dennis

Date:8/16/2009 4:17:17 PM

Thanks geoff
I get the point about not having much high frequency content on the old tapes.

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: cbaudio

Date:8/22/2009 12:59:23 AM

If you are going back to the source tapes, then by all means digitize at 24/96. It's the standard for the LOC (Library of Congress) and the ECU just to mention a few. Who knows what software will come along in the next 10 years or so that will be able to do wonders to your higher resolution archives.

You may have to bake the tapes and re-lubricate them in order to play them again. I do this all the time. You are welcome to email me off list if you need further advice or help.

Cheers!

Corey

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: john_dennis

Date:8/23/2009 11:00:07 AM

Your comment on the standards for the Library of Congress is insightful. I had not considered that actual archivists might have settled on a set of standards.

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: Larry Clifford

Date:8/23/2009 1:09:23 PM

Corey,

Where did you fing the information about digitizing at 24/96? You said it is the standard for the LOC (Library of Congress) and the ECU just to mention a few.

Please explain the numbers above. I use SF 9 in a very simple way, but it works for me so far.

I tried to navigate the LOC Internet site, but did not succeed. I am hoping you might have a link address for the informaiton.

Also, what is ECU?

Thank you for your help,
Larry

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: rraud

Date:8/23/2009 4:32:18 PM

I would not waste hard drive space on 96k from a 1/4 track R-R. (probably 7.5ips.)
88.2kHz would possibly sound a little better than 96k when down-sampled to 44.1 for a CD.

The US gubment is well known for they're efficiency... NOT, and most folks ain't hired for their skills, and that includes speaking English, if you've ever dealt with anyone at the LOC.
My .02 cents.

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: Steven Myers

Date:8/23/2009 6:13:10 PM

If magical future software will be able to correctly imagine the extended upper freqs (which are not on the tape), it will also be able to do the relatively simple task of resampling to make room for them.

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: Geoff_Wood

Date:8/23/2009 6:33:16 PM

.... not to mention creating entire program material spontaneiously !

geoff

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: john_dennis

Date:8/24/2009 10:39:40 AM

"(probably 7.5 ips.)"

Rick,
These tapes were recorded at 7.5 ips.

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: Geoff_Wood

Date:8/24/2009 5:24:02 PM

So the correct answer is " You record at whatever the spec is that the end-user requires".

That being said, there is no OTHER reason to record at more than 44K1 for a 7.5 ips tape, unless by some miracle there is some content above 20KHz.


geoff

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: john_dennis

Date:8/25/2009 10:00:56 AM

Corey piqued my curiosity about standards so I searched for documentation on the standards used by archivists. I don’t expect some software magic to make a Grammy-winning performance out of a live club date recording. At a minimum, I want to faithfully reproduce what I heard on the tape in the past. As each day goes by, the likelihood that I will be able to hear it in the future diminishes. My children, might be candidates for hearing all the subtleties on the original tape but they have likely suffered more ear damage at their ages than I have.
My thanks to Carl Fleischhauer of the Library of Congress for sending this standards document and links to others:
http://www.iasa-web.org/downloads/publications/tc03_english.pdf

"Guidelines on the Production and Preservation of Digital Objects, Second Edition" (2009). (May be ordered from IASA from this page:
http://www.iasa-web.org/special_publications.asp.)

Indiana and Harvard Universities: Sound Directions project report: http://www.dlib.indiana.edu/projects/sounddirections/papersPresent/index.shtml.

Now, I have to decide how much of an archivist I really am. I agree that there is little high frequency content on the tape, because there never was, and that sampling at higher rates will likely produce more samples of similar data. I am in favor of using a higher bit depth without question. It appears that picking any sampling rate to some extent predetermines the delivery rate. The idea proposed that 88.2 KHz would sound better if the final rate was 44.1 KHz seems to indicate that aliasing from the resample from 96 KHz to 44.1 KHz would be worse than from 88.2 KHz.

When this is over, I plan to bulk erase the tapes and sell the drives on eBay.

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: jumbuk

Date:8/25/2009 11:17:28 PM

"When this is over, I plan to bulk erase the tapes and sell the drives on eBay."

Make sure you have thought about backups and media degradation before you do!

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: john_dennis

Date:8/25/2009 11:57:24 PM

I keep a copy spinning and a copy on a USB hard drive. I have never considered any removable media as a legitimate archive methodology. The USB hard drive gets policy replaced as the space requirement grows. This averages about every two years.

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: john_dennis

Date:9/11/2009 4:28:34 PM

Thanks for all the input.
I ran a test of different sample rates and word lengths before arriving at my conclusions.

I recorded the same four minute song at 44.1/24, 48/24, 88.2/24 and 96/24 in Sound Forge 9 and did not process the files at all except to make the start and end points as close to the same as I could. I then resampled all four files to eight new files at 44.1/16 for CD and 48/16 for DVD. I used CD Architect for CD and DVD Architect for DVD. I listened to the CDs from a Denon standalone CD player of decent quality and a Sony Blu-ray/DVD S550 through a Sony ES amplifier and Polk speakers. This rig is middling in performance but may be typical of what might be found in a home.

I could not hear a difference from any of the different sample rates or media sources.

I have settled on 48KHz and 24 bit as the sample rate. The rationale may seem obtuse or rather practical. I have decided to deliver the content on DVD-5 and those parameters are native to DVD. Everyone I know has reasonable sound equipment for playing DVDs. If, for some reason, I need to burn a CD, I will accept whatever alias distortion I get resampling from 48KHz to 44.1KHz. I don’t suspect it will be much. (In my test, I could not hear it.) If someone wants an MP3, it was all a big waste of time, anyway.

Along with having a slightly higher sample rate, DVD has enough space on the media to allow me to include a whole 90 minute tape along with the scans of the boxes and recording notes. I can also save the raw data files that can be played or edited on a computer or media center. So far, I have captured nine tapes… just thirty to go.

Though DVD-5 works fine, I might use a single layer Blu-ray for my own purposes since I can put a large numer of tapes on one disk and I won't have to hunt all over for the different disks.

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: rraud

Date:9/11/2009 5:00:16 PM

John, this maybe of interest to you when down-converting for audio CD.
SF-10 now includes iZotope 64-bit SRC (sample rate conversion) and MBIT+ dither (bit-depth conversion in the iZotope mastering suite.

Subject:RE: Best Sample Rate and Bit Rate for Archivi

Reply by: john_dennis

Date:9/12/2009 9:04:52 AM

rraud

Just went to Version 9, but I'll do a trial of SF 10 soon.