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Audio from vinyl (24 / 96-192 khz). Converting/downsampling?
Taishou
post Aug 27 2012, 03:01
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Hi again

I have several digitized vinyls in FLAC, at 24 bit, 96-192 khz. Is it worth all that sample rate? I was thinking of making CD quality (16/44.1) FLACs or even mp3 320. I doubt I'll ever in my life spend more than, idk, 200 usd in headphones, so the over-quality looks a waste. What do you say? I'm far from an audiophile and I feel pretty happy with mp3 320 (I can't even tell from FLAC).

Anyway, I need to re-encode that at least for my mobile devices. Should I have any special care when converting? I use fre:ac (LAME 3.99.5). Should I just set 44.1 khz when encoding there and done? Or should I downsample with another tool and then encode? I just tried encoding something setting 44.1 in LAME and the result sounds the same as the original 24/192 (with my crappy headphones at least).

The same goes for FLAC or ogg (I tend to use the latter for my DAP). Just setting the sample rate when encoding is enough or is it better to do it with another program? (I doubt, but I wouldn't like regretting later because I made a crappy conversion).

Thanks!


(maybe this should go in the "vinyl" forum, but my concern is more with those high sample rates and downsampling, regardless the source)
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Taishou
post Aug 29 2012, 02:48
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Thanks for all your input, it's really great happy.gif

I just ran into a little "issue". When processing the files with SoX with this command in a batch...

CODE
sox in.wav -b 16 out.wav rate 48k


I got warnings with some files:

CODE
C:\Program Files (x86)\sox-14-4-0>sox aki1.wav -b 16 aki11.wav rate 48k

C:\Program Files (x86)\sox-14-4-0>sox aki2.wav -b 16 aki22.wav rate 48k
sox WARN rate: rate clipped 19 samples; decrease volume?
sox WARN dither: dither clipped 16 samples; decrease volume?

C:\Program Files (x86)\sox-14-4-0>sox aki3.wav -b 16 aki33.wav rate 48k

C:\Program Files (x86)\sox-14-4-0>sox aki4.wav -b 16 aki44.wav rate 48k
sox WARN rate: rate clipped 15 samples; decrease volume?
sox WARN dither: dither clipped 13 samples; decrease volume?

C:\Program Files (x86)\sox-14-4-0>sox aki5.wav -b 16 aki55.wav rate 48k
sox WARN rate: rate clipped 5 samples; decrease volume?
sox WARN dither: dither clipped 4 samples; decrease volume?


Should I care? What do those samples mean? 19 and 16 samples from the 48000 in a second? (each wav is a full disk, an hour long). Should I do something? (I know, "decrease volume", but I wouldn't like to do that for something insignificant). I'm guessing it's just cracks/ticks or noise from the vinyl that have a spike in the audio.

This post has been edited by Taishou: Aug 29 2012, 02:49
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jensend
post Aug 29 2012, 15:13
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QUOTE (Taishou @ Aug 28 2012, 23:47) *
If it matters of something, the files with clipping have a track gain between -2.50 and -2.95 db and a peak of 0.999900 (that's what foobar says at least, exactly the same for the 3). It's more or less the same as the others that went without warnings.

The track gain is the gain adjustment required to reach the perceptual loudness level recommended in the ReplayGain standard, so it's saying your recordings are 2.5-3 dB too loud according to that standard. For resampling purposes it's usually good to have a maximum level of .95 or lower (close to 0.5dB of headroom).
QUOTE (Taishou @ Aug 28 2012, 19:48) *
Should I care? What do those samples mean? 19 and 16 samples from the 48000 in a second? (each wav is a full disk, an hour long). Should I do something? (I know, "decrease volume", but I wouldn't like to do that for something insignificant). I'm guessing it's just cracks/ticks or noise from the vinyl that have a spike in the audio.

It's true that clipping a handful of samples in an hour is probably not worth much worrying about, especially if those are already pops/clicks- which aren't really going to be made worse by a little further distortion- rather than real signal. You'll have to decide whether you want to do anything about it or not.

But before you make that decision you should know there's an easy way to do it and do it well. You don't have to choose between just reducing every file's gain by the same amount (too much for some and/or not enough for others) and manually choosing an appropriate gain for each file (very time consuming). Adding -G to your SoX command line i.e. "sox -G ..." will automatically apply just the right amount of negative gain to prevent clipping and won't lose any precision in intermediate steps; see its manual for details.

You may also want to consider ReplayGain options.
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Posts in this topic
- Taishou   Audio from vinyl (24 / 96-192 khz). Converting/downsampling?   Aug 27 2012, 03:01
- - Porcus   QUOTE (Taishou @ Aug 27 2012, 04:01) I ha...   Aug 27 2012, 06:16
- - Taishou   I see... Thinking about it I'll stay with FLA...   Aug 27 2012, 06:57
- - Taishou   Sorry for the double post, I can't see an ...   Aug 27 2012, 08:25
|- - Porcus   Go 44.1 or 48, as those are the well-supported sam...   Aug 27 2012, 10:14
||- - db1989   QUOTE (Porcus @ Aug 27 2012, 10:14) [Oh ....   Aug 27 2012, 14:38
|- - splice   QUOTE (Taishou @ Aug 26 2012, 23:25) ... ...   Aug 27 2012, 21:37
- - jensend   Try the FAQ for good info and advice. Also this pa...   Aug 27 2012, 16:45
|- - benski   QUOTE (jensend @ Aug 27 2012, 11:45) The ...   Aug 28 2012, 18:37
|- - Woodinville   QUOTE (benski @ Aug 28 2012, 10:37) QUOTE...   Aug 29 2012, 03:27
|- - krabapple   QUOTE (Woodinville @ Aug 28 2012, 22:27) ...   Aug 31 2012, 14:08
- - jensend   Oh, BTW: resampling in multiple stages is unlikely...   Aug 27 2012, 17:06
- - Taishou   Great answers, thanks. I just read the links you p...   Aug 27 2012, 20:56
- - jensend   If you're already using SoX, no reason to not ...   Aug 28 2012, 00:09
- - Taishou   QUOTE (splice @ Aug 27 2012, 17:37) QUOTE...   Aug 28 2012, 05:40
|- - Porcus   QUOTE (Taishou @ Aug 28 2012, 06:40) Afte...   Aug 28 2012, 07:42
|- - jensend   QUOTE (Taishou @ Aug 27 2012, 22:40) Afte...   Aug 28 2012, 17:34
- - db1989   Itís a result of one of audioís many compound myth...   Aug 28 2012, 07:09
- - Woodinville   There is some use to that over-20kHz stuff, though...   Aug 28 2012, 08:16
- - Arnold B. Krueger   QUOTE (Taishou @ Aug 26 2012, 22:01) I ha...   Aug 28 2012, 12:40
- - greynol   We had the same inconvenient point raised about th...   Aug 28 2012, 20:32
- - Taishou   Thanks for all your input, it's really great ...   Aug 29 2012, 02:48
|- - Porcus   QUOTE (Taishou @ Aug 29 2012, 03:48) Shou...   Aug 29 2012, 15:05
|- - jensend   QUOTE (Taishou @ Aug 28 2012, 23:47) If i...   Aug 29 2012, 15:13
- - Taishou   If it matters of something, the files with clippin...   Aug 29 2012, 06:47
- - Porcus   But ... if the peak measures to 0.999, and the res...   Aug 29 2012, 20:43
- - pdq   The resampling produced samples that were beyond +...   Aug 29 2012, 21:02
- - Taishou   Well, I decided to leave it as it is. I tried the...   Aug 29 2012, 23:30
- - greynol   Re. compression: I've seen worse. At the end ...   Aug 29 2012, 23:41
- - Taishou   Indeed. And it's the same on the source, so it...   Aug 29 2012, 23:51
|- - Porcus   QUOTE (Taishou @ Aug 30 2012, 00:51) it w...   Aug 30 2012, 07:35
- - greynol   Could it be due to possible inter-sample overs occ...   Aug 30 2012, 02:51
- - greynol   Off-topic discussion on the SNR or MP3 has been sp...   Aug 31 2012, 19:48


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