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  #1  
Old 04-08-2003, 07:11 AM
D Clarkson D Clarkson is offline
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Default sample rate conversion

I'm on a project with recorded files of 48K,now I want to convert them to 44.1K,so what's the best way to convert them within Pro Tools?
btw,I'm on PC,so if it's not possible with Pro Tools,is there another way,and how??

Thanx! [img]images/icons/grin.gif[/img] [img]images/icons/grin.gif[/img]
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  #2  
Old 04-09-2003, 03:40 AM
AE AE is offline
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Default Re: sample rate conversion

If you just need a 44.1 kHz mix, you can sample rate convert as part of the Bounce to Disk process. If you want to convert your entire session, use the Save Session Copy In command.
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  #3  
Old 04-09-2003, 06:05 AM
D Clarkson D Clarkson is offline
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Default Re: sample rate conversion

o.k. thanx!
what I also wanted to know is what advantage you have when you record acoustical instruments such as drums,guitars,bass,vocals,etc. on 48K instead of 44.1K?
Because a lot of Digital 24-track Tape-recorders like Mitsubishi are running on 48K.
Has it something to do with dynamics?
Can you hear a difference in tonal balance?
I want to know if it's worth to record acoustical stuff on higher sampling-rates... [img]images/icons/confused.gif[/img]
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  #4  
Old 04-09-2003, 11:19 AM
doug_hti doug_hti is offline
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Default Re: sample rate conversion

Quote:
Originally posted by D Clarkson:
o.k. thanx!
what I also wanted to know is what advantage you have when you record acoustical instruments such as drums,guitars,bass,vocals,etc. on 48K instead of 44.1K?
Because a lot of Digital 24-track Tape-recorders like Mitsubishi are running on 48K.
Has it something to do with dynamics?
Can you hear a difference in tonal balance?
I want to know if it's worth to record acoustical stuff on higher sampling-rates... [img]images/icons/confused.gif[/img]
<font size="2" face="Verdana, Arial">The advantage of 48k to 44.1k is not the dynamics, but the frequency response extended. There is a nyquist curve theory or something that says that you are only hearing half of the sample rate, so half of 44.1k is 22 and half of 48k is 24. And even though our hearing range is 20k at best, it seems that a lot of the flaws in digital converters is the filter that does the cut off, so if it is at 22k instead of 24k, if it's a poor AD/DA converter, it may mess up the sound within our hearing spectrum.

Some machines may be standard at 48k not only because of the increased Freq range, but probably because it's more advisable to downsample than upsample (even though both are not ideal) and video/film post production world runs at 48k.

Many people will say it sounds better as well.
I personally think it does, however what can be difficult is when you are mixing a project at 48k in the box and bounce and convert to 44.1k. The mix won't always sound the same as it did at 48k...so in my opinion, that's why some people say that 44.1k sounds better, not because it does, but because they may be getting fewer suprises on the final bounce.

that's all a very loose interpretation of things, but hope it helps. others may explain a bit more. I'm not very technical.
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  #5  
Old 04-09-2003, 02:54 PM
D Clarkson D Clarkson is offline
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Default Re: sample rate conversion

Thanx for the advice!
Maybe it's better for me to put 48K final mixes on a DAT and leave it to the mastering engineer so they can do the conversion for me,because I guess most hi-end mastering suites have "the real" converters to accomplish such tasks.
Or do mastering engineers prefer 44.1K mixes.
Because if I want to have my projects mastered,I think I would like them to make an analog 2-track master.
Any opinions?
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  #6  
Old 04-09-2003, 06:19 PM
PTUser NYC PTUser NYC is offline
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Default Re: sample rate conversion

I think you have two choices, and which is better should be decied by which feels better to you, and which you have the hardware for.

1) Your idea of staying at 48kHz, and letting the mastering guy deal with it is a fine solution. Obviously, you would have preferred to work at 44.1kHz all the way through, but since its too late for that, leave it to the mastering guy.

2) Print your mix through some analog compressor or something, and record it @ 44.1kHz, or on analog tape to an external device. This is a great idea IF your external 44.1kHz device has good converters, or you have a good sounding analog machine. If we're talking about a Panasonic 3500 or a Tascam 1/4" machine here, then I'd go with the first option.

Option one i pretty good, because the chances are that the mastering guy has better gear available. BUT, if you do have good gear for the recording, then there is the benefit of making mix decisions while hearing the effect of the tape or compressor etc.

There is no clear winner here, not knowing what your external option would be.
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  #7  
Old 04-09-2003, 06:33 PM
D Clarkson D Clarkson is offline
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Default Re: sample rate conversion

Call me an idiot but I don't get it:
How aboout the people recording and mixing at 192K?Imean,if they have to downsample their stuff to 44.1K ,I guess there would be nothing left of the audio.
How do they make sure that most of the quality is preserved when they want their mixes on cd??? [img]images/icons/confused.gif[/img] [img]images/icons/confused.gif[/img] [img]images/icons/confused.gif[/img]
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  #8  
Old 04-09-2003, 06:43 PM
Mark Staples Mark Staples is offline
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Default Re: sample rate conversion

Quote:
Posted by D Clarkson
--------------------------------------------------------------------------------
Thanx for the advice!
Maybe it's better for me to put 48K final mixes on a DAT and leave it to the mastering engineer so they can do the conversion for me,because I guess most hi-end mastering suites have "the real" converters to accomplish such tasks.
Or do mastering engineers prefer 44.1K mixes.
Because if I want to have my projects mastered,I think I would like them to make an analog 2-track master.
Any opinions?
<font size="2" face="Verdana, Arial">FWIW, I just finished a project and one of the songs was accidentally recorded at 44.1K while the rest were recorded at 48K. When I was preparing to send the mixed down songs to the mastering house, I told them of the one song. Their comment was that they PREFERRED 48K but could still deal with the 44.1K.
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  #9  
Old 04-10-2003, 12:15 AM
doug_hti doug_hti is offline
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Default Re: sample rate conversion

I think that most mastering engineers want the highest resolution that you recorded the material at, because they can typically convert at a much higher quality than most studios, however, much more often than not, most mastering engineers run the mix through analog gear, in which it has to go through another DA/AD process, in which at this point, the mastering engineer can recapture the audio digitally at the intended master resolution (44.1).

As far as doing something at 192k. No it's not a waste IMO. and again, especially if it runs through analog gear.

I agree that the difference between 48 and 44.1 is barely negligible. And I definately agree that a lot of software SRC schemes ruin any inherant advantages of recording at 48k, unless of course you're running it through analog gear at mixdown to the intended sample rate.

I don't know what others of you have experienced with higher sample rates, but at the higher 88.2 and 96k sample rates, I can hear an considerable difference in the upper end shelving.
For example on a avalon 737, there is a 32k shelving option. I can hear whatever interaction it's doing within the audible range far sooner than if I try to do the same at 44.1 or 48k session, in which it's actually not even very pleasing, a bit more plastic.


As far as why 44.1k exists....I had no idea about that, very interesting info.
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  #10  
Old 04-10-2003, 01:44 AM
PTUser NYC PTUser NYC is offline
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Default Re: sample rate conversion

I both agree, and don't agree...

I agree that the Nyquist theorem dictates that you can only reliably sample frequencies up to half the sampling rate.

I agree that 44.1kHz samples won't reproduce audio above 22.05kHz, and that 48kHz samples won't reproduce audio above 24kHz.

Most people agree that we cannot really hear anything at 22kHz, so any real world distinction between the two rates is meaningless.

I also agree that anti aliasing filters will do "brickwall" cutoff of everything above the nyquist frequency (half the sampling rate).

I also agree that there is no such thing as a perfect brickwall filter, and that some lower frequencies will also be affected.

The rub comes when you look at how steep the slope of the filter is. Certainly in 1990, antialiasing filters could (and usually did) cause phase anomolies in frequencies that extended down well into the audible band. Even frequencies as low as 16kHz were often affected. Early CDs and CD players sounded "harsh" and "thin", while samplers like the Syncalvier which were capable of 100kHz sampling rates sounded much better. Since we had poor antialiasing filters, it made sense to push the Sampling rate up in order to put all the phase junk out of the range of our hearing.

Nowadays, we have much better filters. The slope is so steep that no phase anomolies extend down into the audible range. The modern audible difference between 44.1kHz sampling rates and 48kHz sampling rates is negligible, if any.

Historically, 48kHz was chosen as the "professional" sampling rate. Then consumer gear came along, and in an effort to foil pirating, a sampling rate which was poorly mathematically related to the 48kHz standard was chosen. 44.1kHz was specifically chosen precisely because it does a poor job of sample rate convert to and from 48kHz.

A lot of pro gear still runs at 48kHz because it is the "pro" standard, and because some folks (like the previous poster) believe that more is better. Marketing pressures keep 48kHz around.

Now, if you are going to mix to analog tape or something, using 48kHz or 44.1kHz is likely to make no difference whatsoever. You pick your rate, and you use it throughout the project. The problem comes when you are staying digital, like many of who mix "in the box" do. Now you've got a final master which will end up being digital, and either 48kHz or 44.1kHz.

When you go to make an audio CD, which is going to be 44.1kHz, you are either going to make a direct copy, or you are going to do a sample rate convert. And remeber, a SRC from 48kHz to 44.1kHz will not sound great. 44.1kHz was chosen precisely to make trouble for SRC algorhythms.

Now, just like our filters have gotten better, our SRC algorhythms have too. I'm not saying you can't get good results doing a SRC - but I am saying that whatever extra quality you get from recording at 48kHz in the first place (none in my opinion) is certainly less than you lose in a SRC, even a good one.

My advice is to use a good converter (whatever you do!) and work at 44.1kHz if you are staying digital.
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