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Aleron Ives
post Dec 13 2010, 02:23
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After a bit of searching, I failed to find any specific answers, so I hope I'm not repeating a commonly-asked question. I'm planning to make digital recordings from vinyl by using the line-in jack on my PC with a Sound Blaster Audigy 2 sound card. I was planning to use Audacity to do the recording, and I was wondering if there is any real purpose to using 24 bit and/or a high sample rate like 88,200 or 96,000 Hz when originally recording. The final destination will be typical 16 bit 44,100 Hz, but if I decide to try do do click/pop or noise removal, is there any benefit from doing such work at a higher quality and then reducing the sample rate and bit depth later, rather than doing all the manipulation at an initial setting of 16/44? The only topic on this subject that I found was this one:

http://www.hydrogenaudio.org/forums/index....showtopic=61758

Also, Audacity allows you to record with 32 bit float as well, but I'm quite sure that my sound card doesn't support it. Is there any way to verify that the sound card actually does output 24 bit when you're recording at that depth? If there is, I haven't found any way to configure it, except in the media player supplied by Creative, which allows you to select the bit depth for recording (but presumably only for it, not for other programs like Audacity). Any assistance would be greatly appreciated.
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cliveb
post Dec 13 2010, 09:53
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QUOTE (Aleron Ives @ Dec 13 2010, 01:23) *
The final destination will be typical 16 bit 44,100 Hz, but if I decide to try do do click/pop or noise removal, is there any benefit from doing such work at a higher quality and then reducing the sample rate and bit depth later, rather than doing all the manipulation at an initial setting of 16/44?

The advantage of processing at 24 bit is that if you do a heck of a lot of DSP, then you are less likely to accumulate sufficient rounding errors that the quantisation noise becomes audible above the intrinsic noise of the source material. That said, the level of vinyl surface noise is so high that you'd have to do dozens of passes before this theoretical danger actually becomes real.

The disadvantage of processing at 24 bit is that there are some useful vinyl restoration tools out there that only operate at 16 bit. Working at 24 bit means you deny yourself access to those tools.

QUOTE (Aleron Ives @ Dec 13 2010, 01:23) *
Also, Audacity allows you to record with 32 bit float as well, but I'm quite sure that my sound card doesn't support it. Is there any way to verify that the sound card actually does output 24 bit when you're recording at that depth?

That's not an issue when you're dealing with vinyl sources. Even if you decide to process at 24 bit, it is safe to record at 16 bit and convert to 24 bit afterwards (either as a separate step or by the recording software doing it on-the-fly).
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Aleron Ives
post Dec 13 2010, 21:25
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Thanks for all the input so far. I do have a few more questions, though.

QUOTE (cliveb @ Dec 13 2010, 01:53) *
That's not an issue when you're dealing with vinyl sources. Even if you decide to process at 24 bit, it is safe to record at 16 bit and convert to 24 bit afterwards (either as a separate step or by the recording software doing it on-the-fly).

Since no extra precision is gained if you increase the bit depth afterwards, is this just a case of using a higher-quality "container" for the editing process so that each edit produces minimal rounding errors, thus when you convert back to 16 at the end, the final result has fewer rounding errors than if you did multiple edits on the original 16-bit recording?

Since recording at 24/96 seems to be out of the question for my hardware, is there really any point in recording at 16/96 or 16/88, or is there no real benefit? I would assume if there is any, it would again just be to reduce potential errors from multiple passes of processing, but since error would also be introduced by resampling back to 16/44 in the final step, is it better to just record at 16/44 in the first place?

Finally, is there a "best" strategy to deal with the recording volume? Is it better to ensure there is no clipping by setting the recording volume at ~50% and then using a program like SoX to raise the volume later while guarding against clipping, or should the recording volume be set higher (like say, to make the loudest track on the record be as loud as possible without clipping)?
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DonP
post Dec 13 2010, 22:01
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QUOTE (Aleron Ives @ Dec 13 2010, 15:25) *
Since no extra precision is gained if you increase the bit depth afterwards, is this just a case of using a higher-quality "container" for the editing process so that each edit produces minimal rounding errors, thus when you convert back to 16 at the end, the final result has fewer rounding errors than if you did multiple edits on the original 16-bit recording?

Pretty much, yes.

QUOTE
Finally, is there a "best" strategy to deal with the recording volume? Is it better to ensure there is no clipping by setting the recording volume at ~50% and then using a program like SoX to raise the volume later while guarding against clipping, or should the recording volume be set higher (like say, to make the loudest track on the record be as loud as possible without clipping)?


You might want to experiment a bit and see if your soundcard gives you any extra headroom when recording to floating point. At any rate I try to stay within 2-3 dB of the 16 bit max and normalize at the end using that function in Audacity. For the most part I don't have to mess with the record level once it's set.

Other things to do before going after the scratches (I think these are addressed in the Audacity documentation) are 1) normalize the zero average (remove any DC bias), and 2) apply a high pass filter at 20 hz (higher if you know there aren't any deep bass fundamentals)
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Posts in this topic
- Aleron Ives   Vinyl -> Digital   Dec 13 2010, 02:23
- - saratoga   I'd probably just record at whatever the highe...   Dec 13 2010, 02:27
- - Aleron Ives   If I select to record at 96/24 in a program like A...   Dec 13 2010, 05:07
|- - saratoga   QUOTE (Aleron Ives @ Dec 12 2010, 23:07) ...   Dec 13 2010, 05:09
- - Juha   Audigy 2 does support 24/96 but, it's same res...   Dec 13 2010, 05:55
|- - Aleron Ives   QUOTE (Juha @ Dec 12 2010, 21:55) Audigy ...   Dec 13 2010, 06:42
|- - Brod   QUOTE (Juha @ Dec 13 2010, 12:55) To test...   Feb 9 2012, 07:26
|- - pdq   QUOTE (Brod @ Feb 9 2012, 02:26) QUOTE (J...   Feb 9 2012, 18:14
|- - greynol   QUOTE (Brod @ Feb 8 2012, 22:26) You...   Feb 9 2012, 18:52
- - rkay5   Hi, I recorded a lot LP's and I have found ...   Dec 13 2010, 07:30
|- - greynol   It was actually primarily directed at the last par...   Dec 14 2010, 20:57
- - greynol   Per our Terms of Service to which you agreed upon ...   Dec 13 2010, 07:39
|- - 2Bdecided   QUOTE (greynol @ Dec 13 2010, 06:39) Per ...   Dec 14 2010, 14:44
- - cliveb   QUOTE (Aleron Ives @ Dec 13 2010, 01:23) ...   Dec 13 2010, 09:53
|- - Aleron Ives   Thanks for all the input so far. I do have a few m...   Dec 13 2010, 21:25
|- - saratoga   QUOTE (Aleron Ives @ Dec 13 2010, 15:25) ...   Dec 13 2010, 21:30
|- - DonP   QUOTE (Aleron Ives @ Dec 13 2010, 15:25) ...   Dec 13 2010, 22:01
|- - cliveb   QUOTE (Aleron Ives @ Dec 13 2010, 20:25) ...   Dec 14 2010, 09:39
|- - DonP   QUOTE (cliveb @ Dec 14 2010, 03:39) Provi...   Dec 14 2010, 13:30
- - greynol   Unless you know that you're going to have a pr...   Dec 13 2010, 22:01
- - Juha   QUOTE Since recording at 24/96 seems to be out of ...   Dec 13 2010, 22:07
- - greynol   I only scanned those links, but didn't see any...   Dec 13 2010, 22:12
- - Juha   QUOTE I think you're probably best off recordi...   Dec 13 2010, 22:15
- - greynol   Ok so they still didn't get it right with the ...   Dec 13 2010, 22:20
- - LocrianGroove   Has anyone done any testing to determine the minim...   Dec 15 2010, 04:36
|- - saratoga   QUOTE (LocrianGroove @ Dec 14 2010, 22:36...   Dec 15 2010, 06:42
|- - cliveb   QUOTE (LocrianGroove @ Dec 15 2010, 03:36...   Dec 15 2010, 10:44
|- - LocrianGroove   QUOTE (cliveb @ Dec 15 2010, 04:44) It wa...   Dec 15 2010, 19:13
- - kraut   QUOTE We've been doing the calculations based ...   Dec 15 2010, 07:11
|- - LocrianGroove   QUOTE (kraut @ Dec 15 2010, 01:11) QUOTE ...   Dec 15 2010, 19:05
- - AndyH-ha   There is the noise level as recorded and the noise...   Dec 15 2010, 08:53
- - Brod   There's no such thing as a dead discussion - t...   Feb 10 2012, 08:46
- - Canar   QUOTE (Brod @ Feb 8 2012, 22:26) QUOTE (J...   Feb 10 2012, 08:51


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