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[PC] Recording with several settings at once ?
Xrcr9709
post Jan 27 2013, 19:40
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Hello,

I'm currently digitizing and archiving my old cassettes. I have already recorded everything in 16-bit 44.1 kHz.

I would like now to re-record everything in 24-bit 44.1 kHz and 24-bit 48 kHz

I was wondering if it made sense to play on tape and open two programs (in my case it would be Sound Forge Pro and Audacity), one recording 24-bit 44.1 kHz, the second one recording 24-bit 48 kHz.
(My sound card is an Asus Xonar Essence STX.)

It looks like it works, but can it have an impact on the recording quality ?

Thank you for informations.
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db1989
post Jan 27 2013, 21:08
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Why do you need to record to multiple sets of parameters instead of simply recording to the highest and down-converting later if, for whatever unspecified reason, you need to?
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AndyH-ha
post Jan 27 2013, 22:18
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I think that takes the cake for amazing way to waste time and put more wear and tear on the tape equipment.

Recording two or more different copies at once, at different specifications, has to mean that the data coming out of the ADC is being resampled to those multiple specifications before being routed to the different applications, most likely by Windows. That means that if there were potentially something different to capture at those different rates and bit depths, you would not be accomplishing accessing that difference. I've seen complaints about the quality of Windows resampling but haven't paid much attention to what is what there, but for sure you can do better with good post recording applications than by letting Windows do it.

You already have everything you can possibly get off the tape with your first recording at 16/44.1 (assuming you are going to be using the same equipment to do the additional recordings); you will capture nothing more in recording at different rates or bit depths. If, for whatever hard to guess reason you want one or more of those others specs at any time, software resampling in a decent application will be much faster and more accurate than re-recording.
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Xrcr9709
post Jan 27 2013, 22:34
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QUOTE (AndyH-ha @ Jan 27 2013, 22:18) *
has to mean that the data coming out of the ADC is being resampled to those multiple specifications before being routed to the different applications, most likely by Windows. That means that if there were potentially something different to capture at those different rates and bit depths, you would not be accomplishing accessing that difference.


That what I thought and wanted to check.


And why I'm recording with different specs is not really the point of this topic but is a mix of these:
- I don't want to want to re-record my tapes any day in the future. (I wanted to be able to throw the tapes away without regret, though I will probably keep them sealed somewhere)
- In the past I've been doing music projects as well as video projects, following inspiration and I have no idea what the future will be
- I'm not currently working on a specific project but consitutating a definitive archives/master of my old tapes (should have done it a while ago)
- I've read it was not advised to resample.
- I've read that it's alway best to record in 24-bit for some audio working (and again I don't know what the future will be), but I've read that after I had finished the 16/44.1 recording.
- I don't have some many tapes that I think I would have to worry about wear and tear on the tape equipment. (around 30 tapes)

But I agree the main thing was to record everything at 16/44.1

This post has been edited by Xrcr9709: Jan 27 2013, 22:42
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pdq
post Jan 27 2013, 23:32
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Recording at 24 bits is advisable if you are going to do any kind of processing. That does not mean you need to save it permanently as 24 bits, so as soon as you have done your processing you may as well convert to 16 bits.

There is no problem resampling from 48 to 44.1, especially if you do this at 24 bits. It makes more sense, though, to decide what sampling rate you need and stick to it. For example, if you ever intend to burn to CD then you should record at 44.1.

Edit: If you don't intend to do any kind of post processing, such as hiss reduction, then just keep the 16/44.1 files. They are just fine.

This post has been edited by pdq: Jan 27 2013, 23:34
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Xrcr9709
post Jan 27 2013, 23:50
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The problem is that I read plenty of theories about all of these.

But so you mean that
16bit --> 24bit is lossless ?
24bit --> 16bit is lossless ?
48/24bit --> 44.1/24 bits is lossless ? (I read that any resampling, except multilpying by integer number/and maybe dividing by two, is lossy)
44.1/24bit --> 48/24 bits is lossless ? (same thing)

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pdq
post Jan 28 2013, 00:24
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Out of all of these, only 16 --> 24 is lossless, but that is not the point.

Compared to the noise and distortion inherent in tape, all of them are audibly indistinguishable. The only possible exception was some early sound cards that did a poor job of upsampling 44.1 to 48. These days that is not a problem.
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Xrcr9709
post Jan 28 2013, 00:45
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Then I still have the impression that

Tape * is lossly (at lot) and resampling is lossy (a little bit), which gives LOSSY x lossy.
While not having to resample or resampling by multiplying by 2 gives LOSSY x lossless. Which is a little bit better.

* Though tape is the only source I have for theses recordings so from a relative point of view it's lossless since it's my only source.


Maybe I could then drop the idea of 16/48 and keep only the 24/48
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pdq
post Jan 28 2013, 00:53
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Resampling is still lossy, even if by an integer factor, but the loss should be very small in any case.
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Xrcr9709
post Jan 28 2013, 01:21
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Upsampling from 48 kHz to 96 kHz is lossy ?

I would have thought it wasn't.
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AndyH-ha
post Jan 28 2013, 03:34
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In the strictest sense of the word, resampling is "lossy" in the sense of being unable to reverse the transform and get a result that is bit identical to the original. However, properly done resampling is not lossy in the sense of losing anything. No frequencies will be gone or in any way changed unless the resampling is to such a low sample rate that it does not encompass all the frequencies actually in the original. No nuances of performance, rhythm, beat, harmony, melody, or whatever, will disappear or degrade. The music will not be altered in any way that human sense can detect.

With cassette, it may be theoretically possible to approach the high frequency cutoff of 44.1kHz sampling, but in practice the highest frequencies actually on the tape will be markedly lower than that limit unless you have the very highest end tape machine, in perfect condition, the very best tape, recorded under the very conditions, with music that actually produced some of those high frequencies, recorded with equipment that could actually capture those higher frequencies.

All this coming together is not very likely and most cassette decks could not get anything significant off the tape at those higher frequencies even if they were there. Even with the very best cassette player, you won't reproduce the highest frequencies on many cassettes unless the player itself is carefully aligned to that particular individual tape when you play it. In other words, there is nothing to gain from recording at a sample rate higher than 44.1kHz.

Recording at 24 bit, or floating point, makes setting the levels a little easier but unless you recorded to digital at too low an input level, your recording will be into nothing but background noise long before plumbing the depths of 16 bit. You can't capture anything more by recording at 24 bit.

Processing your digital recording (noise reduction, EQ, editing, etc.) is theoretically better at 24 bit, or (better) floating point, because the cumulative quantization errors are smaller, but you will never be able to actually hear a difference.

If you want to error on the side of caution and process at the greater bit depth, you don't need to have originally recorded at 24 bit (as per the previous paragraph). Since there would not be anything but background noise in those least significant bits if you had recorded at 24 bit, simply converting from 16 bit to 24 bit or floating point gives you a functionally identical product. There isn't any actual benefit to having recorded at 24 bit to begin with, or any loss to having recorded at 16 bit.

Upsampling by an integer amount may or may not be "lossy" according to the first definition above. Some of the best resampling programs recalculate every sample value, some just calculate a new sample value in-between every existing sample. The math isn't anything to which I can speak with authority but I have verified 2X upsampling to contain none of the original sample values in some very excellently resampled audio. However, even if you use a program which just calculates additional sample values, without altering the original sample values, that doesn't mean going back to the original sample rate will be a process of just throwing out the new samples and ending up with the bit identical file as the original; i.e. it will not be lossless.
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Arnold B. Kruege...
post Jan 29 2013, 15:47
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QUOTE (Xrcr9709 @ Jan 27 2013, 18:45) *
Then I still have the impression that

Tape * is lossly (at lot) and resampling is lossy (a little bit), which gives LOSSY x lossy.


Ain't the same lossy.

Tape lossy is at least 10 times more lossy than good resampling lossy.

In engineering, we consider any problem that is 10 times less than some other problem to be easy to ignore.
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