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  #1  
Old 06-19-2003, 08:51 PM
StainedClass StainedClass is offline
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Default 44 or 48

What are you recording at 44 or 48
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  #2  
Old 06-19-2003, 09:10 PM
clorox clorox is offline
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Default Re: 44 or 48

If your goal is to record to produce a CD at the end, then 44.1 is the only way to fly. The reason is that CD's are at 44.1, switching down from 48 produces artifacts.
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Old 06-19-2003, 09:31 PM
Doc Doc is offline
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Default Re: 44 or 48

Agreed. I use 44.1K for CD and 48K for video / DVD. Always 24 bit.
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Old 06-19-2003, 09:53 PM
rwhitney rwhitney is offline
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Default Re: 44 or 48

Has anyone tried converting from 48 to 44.1 using a really good sample rate converter (Z-sys, Weiss, etc)? I wonder if anything could be gained that way? Does 48k sound better to anyone than 44.1? To go a step further, is anyone recording at 88.2, then converting to 44.1 for a better sound? (I don't want to hear about no Nyquist theorem now... ;-)
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  #5  
Old 06-19-2003, 10:21 PM
StainedClass StainedClass is offline
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Default Re: 44 or 48

I usually do 44 for music and 48 for DV too. I just have a friend who cliamed that tracking at 48 would get you better sound....
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Old 06-20-2003, 06:18 AM
dkrz dkrz is offline
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Default Re: 44 or 48

If you use the "tweak head" option for your SRC, the results are very, very good. Now that my new Mac is fast enough to do this without needing to make a pot of coffee during the process. [img]images/icons/smile.gif[/img]

I agree with the other responses though. Unless your doing video work, go with
44.1khz x 24bit

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  #7  
Old 06-20-2003, 08:35 AM
Duardo Duardo is offline
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Default Re: 44 or 48

Quote:
Has anyone tried converting from 48 to 44.1 using a really good sample rate converter (Z-sys, Weiss, etc)? I wonder if anything could be gained that way?
<font size="2" face="Verdana, Arial">There are some sample rate converters (like the ones you mentioned) that really do a good job and don't seem to "harm" the audio at all...however, unless your particular converter sounds better at 48 kHz, there's no advantage to doing that. And there's no reason any modern converter should sound any better at 48 kHz than 44.1. We're talking about less than a tenth of an octave of extra information here, and it's outside the range of human hearing anyhow.

Quote:
To go a step further, is anyone recording at 88.2, then converting to 44.1 for a better sound? (I don't want to hear about no Nyquist theorem now... ;-)
<font size="2" face="Verdana, Arial">Same thing...if you have a converter that sounds better at 88.2 than it does at 44.1, by all means record at 88.2. In general, though, what you'll wind up with is the same thing you'd wind up with recording at 44.1 in the first place...you may not want to hear about Nyquist, but it still applies once the signal's been recorded...

-Duardo
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  #8  
Old 06-20-2003, 08:54 AM
losttimestudios losttimestudios is offline
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Default Re: 44 or 48

What is the use of recording at 96 on a DIGI 002 (other than consuming more disk space) or even higher on HD systems if the end result is going to be an audio CD?
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  #9  
Old 06-20-2003, 03:46 PM
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Park Seward Park Seward is offline
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Default Re: 44 or 48

According to the specs of the 001, there is NO difference in frequency response between 44.1k and 48k.

Interpolation is not pretty:

[From Ed Hall, edhall@rand.org:]

For a start, look at Multirate Digital Signal Processing by Crochiere and Rabiner (see FAQ section 1.1).

Almost any technique for producing good digital low-pass filters will be adaptable to sample-rate conversion. 44.1:48 and vice-versa is pretty hairy, though, because the lowest whole-number ratio is 147:160. To do all that in one go would require a FIR with thousands of coefficients, of which only 1/147th or 1/160th are used for each sample--the real problem is memory, not CPU for most DSP chips. You could chain several interpolators and decimators, as suggested by factoring the ratio into 3*7*7:2*2*2*2*2*5. This adds complexity, but reduces the number of coefficients required by a considerable amount.

[From Lou Scheffer:]

Theory of operation: 44.1 and 48 are in the ratio 147/160. To convert from 44.1 to 48, for example, we (conceptually):

1. interpolate 159 zeros between every input sample. This raises that data rate to 7.056 MHz. Since it is equivalent to reconstructing with delta functions, it also creates images of frequency f at 44.1-f, 44.1+f, 88.2-f, 88.2+f, ...
2. We remove these with an FIR digital filter, leaving a signal containing only 0-20 KHz information, but still sampled at a rate of 7.056 MHz.
3. We discard 146 of every 147 output samples. It does not hurt to do so since we have no content above 24 KHz. In practice, of course, we never compute the values of the samples we will throw out.

So we need to design an FIR filter that is flat to 20 KHz, and down at least X db at 24 KHz. How big does X need to be? You might think about 100 db, since the max signal size is roughly +-32767, and the input quantization +- 1/2, so we know the input had a signal to broadband noise ratio of 98 db at most. However, the noise in the stopband (20KHz-3.5MHz) is all folded into the passband by the decimation in step 3, so we need another 22 db (that's 160 in db) to account for the noise folding. Thus 120 db rejection yields a broadband noise equal to the original quantizing noise. If you are a fanatic, you can shoot for 130 db to make the original quantizing errors dominate, and a 22.05 KHz cutoff to eliminate even ultrasonic aliasing. You will pay for your fanaticism with a penance of more taps, however.
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  #10  
Old 06-20-2003, 07:49 PM
StainedClass StainedClass is offline
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Default Re: 44 or 48

Isnt the only reason to work in 48k for video -sync?

What if I have music that is going to be for video and destined for CD too?
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