The No.1 Website for Pro Audio
Tape Speed
Old 2 weeks ago
  #1
Gear Addict
 
16/44.1's Avatar
 

Tape Speed

I've received a file from analogue tape which runs to fast.
What is the best software to slow it down without sacrifice the sound?
Old 2 weeks ago
  #2
DAH
Lives for gear
 
DAH's Avatar
It is called source butchering. Or pulling out a rotten tooth through one's ass.
Get the transferring guy set the correct speed right on the deck and have him transfer at the highest rate/24 bit depth.
Old 2 weeks ago
  #3
Lives for gear
 
misjah's Avatar
 

Verified Member
You can change the samplerate and correct it that way. Not ideal but sure better than any software.
Old 2 weeks ago
  #4
Gear Head
 
darkalex's Avatar
 

Verified Member
do you know the exact intended length of the original recording ?

if yes then simply calculate the change in length from original to what you received in percentage, then use a high-quality pitch shifting tool and pitch shift the record by the percentage you calculated

Sure it's gonna be a bit degraded, though it may not sound degraded a lot, it'll do the job if there's absolutely no way to get new tape to digital transfers.

Hope this helps!
Old 2 weeks ago
  #5
Gear Guru
 
Thomas W. Bethe's Avatar
 

Verified Member
Most pro audio tape decks have a "pitch control". Just have the sender adjust the pitch control and send you another file. Pretty simple.

BTW how much off is the file in terms of speed???
Old 2 weeks ago
  #6
Gear Addict
 
16/44.1's Avatar
 

The analogue tape is not available anymore.
All there is is a 24/96 file.
Yes i know how speed must be.
So it's software i need.
Only the best please.
Anyone?
Old 2 weeks ago
  #7
Gear Head
 
darkalex's Avatar
 

Verified Member
If you know the length of the original recording, then calculate the change in length of the new recording and then use a pitch shifter tool in some software like GarageBand to get it where you want.
Old 2 weeks ago
  #8
Lives for gear
 
Trakworx's Avatar
Since it's a tape speed issue, you don't need to worry about maintaining the current pitch as you change the tempo, which makes the whole thing much easier on whatever processor you use. I've found that for this kind of job the built in "Pitch" Audio Suite plugin in Pro Tools is capable. Serato Pitch 'n Time is a reputable 3rd party plugin though it may be overkill for this. There are numerous options. Again, this is a relatively easy process so spending a lot of money on a plugin may be a waste. Who knows, maybe even GarageBand is good enough! I'd start by trying whatever pitch plugin may already be in your DAW and use your ears. Best of luck!
Old 2 weeks ago
  #9
Gear Head
 
darkalex's Avatar
 

Verified Member
Trakworx's right, GarageBand only supports 24Bit 48Khz Audio, It'll resample your file and you don't wanna risk passing the audio through an unknown - just for fun - sample rate converter.

You may use the ProTools Plugin suggested by Trakworx or could use just about any other DAW since all have this basic tool to pitch-shift audio.

Mind you I'm just a high school kid messing around on Gearslutz and you might want to hear what the pros are saying on the forum.

Cheers !
Old 2 weeks ago
  #10
Lives for gear
 
Miles Flint's Avatar
 

How much too fast is it? Back to a tape, pitch control there, re-record?
Sounds pretty adventurous ...
I like Sequoia's time-/pitch-correction and resampling tools, 2nd try would be SoundForge.
Old 2 weeks ago
  #11
Gear Maniac
 

how about changing the samplerate tag only, in RX?
Old 2 weeks ago
  #12
Lives for gear
 
misjah's Avatar
 

Verified Member
Like i said, calculate the correct sample rate, print, record, done. Done this many times.
Old 2 weeks ago
  #13
Lives for gear
 
Greg Reierson's Avatar
 

Verified Member
Quote:
Originally Posted by misjah View Post
Like i said, calculate the correct sample rate, print, record, done. Done this many times.
Yes. This is by far the cleanest method.
Old 2 weeks ago
  #14
Lives for gear
 
Trakworx's Avatar
Quote:
Originally Posted by misjah View Post
Like i said, calculate the correct sample rate, print, record, done. Done this many times.
I have been under the impression that this is essentially how many speed change plugins work internally when 'maintain pitch' is disabled. I could be wrong...
Old 2 weeks ago
  #15
Lives for gear
 
Greg Reierson's Avatar
 

Verified Member
Probably. Hopefully. But this method guarantees it.
Old 1 week ago
  #16
Gear Nut
 

Like others said, change the sample rate by the appropriate amount.

Alternatively [for no particular reason : )]:

Two DAWs,

pitch to the second one running fast [like the second DAW is running fast by the exact amount that the track is fast],

then play back at regular speed.



KOTS
Old 1 week ago
  #17
Lives for gear
 

Hi, as others mentioned, I'd try to simply change sample rate. If it is really just twice as fast compared to original speed (like going from 19 to 38 cm/s), then that's the simplest and pretty much lossless way (because no samples gets changed, it just override information about sample rate in wave file header).
So to slow down the 96000 file, you simply override its sample rate to 48000, so it will play at half speed in result.

There couple ways how to do that.
If you use Windows, then you can grab free Voxeng R8Brain. That's primarily sample rate converter, but if you leave resampled output rate the same as for input file (eg. 96k) and fill-in the field "Set sample r8:" to 48000, it should do the trick.

Alternatively is you're on Mac, you can install command-line sox (easiest way is to use homebrew install sox, or you can grab binary at sourceforge). There you can achieve the same effect by command:
sox -S -r new-rate input_file.wav output_file.wav ( eg. sox -S -r 48000 my_great_tape_96000.wav slowed_down_output.wav )

Also some DAWs can do that on import. Like in Pro Tools, there you make new session with 48k working rate, add 96k file and just ignore warning, it will be playing at different speed (that's what we want ).

Finally if overridden 48k rate isn't your intended output (like you'd make a CD or so with 44.1k rate), you'll normally use any suitable SRC converter.

Michal
Old 1 week ago
  #18
Gear Head
 
S_mask's Avatar
 

Sure, try changing the sample rate in case it's just a 2x / half-x issue, and see how it sounds. If the tape used any of the two slower IEC speeds (IEC1), it's essentially only a sample-rate issue. If it was a 7.5 in/s NAB tape, played back at 15 in/s NAB, there are corrections that could have been, or still should be, applied to the digitization of it.

{See attachments, below, for using an MRL tape of 7.5 in/s NAB to calibrate a known-good machine at 15 in/s NAB, and vice versa, for a glimpse at the zones of relative want and over-abundance when crossing over, so to speak.}

Audio Vingnettes' Richard Hess is perhaps the world's best living authority on tape transfers. His website has a lot of useful information. Here's one such page related to your tape transfer's speed issue.

http://richardhess.com/notes/formats...-audio/speeds/

If the recording is voice only, the difference between a 2x and 1x eq might not matter, especially since you no longer have the (defacto) master tape.

If the recording was made on a machine with a marginal speed issue, there might be more or less acceptable results - especially for good music sound, lest the recording machine's selected (or default), or effective, eq standard didn't line up well with that of the reproduce machine.


The Magnetic Reference Lab's website has many helpful papers covering the topics of eq standards at various standard tape speeds and track format specifications that could affect channel separation, good signal to noise, and cross-talk.

http://www.mrltapes.com/index.html

http://www.mrltapes.com/choo&u.pdf

Since you have only the digitization, the best bet, if budget allows, is to send the .wav file to Plangent Processes to see if they can repair not only the speed issue but also the eq and wow and flutter components that got baked into the tape during record and into the capture, during digitization. Jamie Howarth will have the good, bad, and ugly news for you, if you choose this ideal path. It can transform a blurry sound into much clearer tonality, without losing truly-desirable 'analog warmth'.

Also, since you probably don't have enough documentation about the lost tape reel's settings and state of repair at the time of the digitization, let alone about the recording machine, it will be quite permissible and advisèd to experiment with corrective equalization of the capture, once it's at the desired pitch.

<< brrrrrrrrrrrt! Sabor! >>
Attached Thumbnails
Tape Speed-screen-shot-2020-05-16-8.27.31-am.png   Tape Speed-screen-shot-2020-05-16-8.54.19-am.png  
Old 1 week ago
  #19
Lives for gear
 

Verified Member
Quote:
Originally Posted by 5.333V View Post
how about changing the samplerate tag only, in RX?
+1 for this, easiest and best sounding solution !!
Old 1 week ago
  #20
Gear Nut
 

Quote:
Originally Posted by Miles Flint View Post
How much too fast is it? Back to a tape, pitch control there, re-record?
Sounds pretty adventurous ...
This would probably work too.

Seems to me that there are several ways to do it. One just has to accept that none of them are going to be totally transparent.

Post a little bit of the file you having problems with, and we could probably tell what would probably work best.


KOTS
Old 1 week ago
  #21
Lives for gear
 
Alexey Lukin's Avatar
 

Verified Member
On the contrary, all these ways are totally transparent and work equally well. Choose the one that fits your workflow best.
Topic:
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump