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Recording, Bit Depth & Sample Rates ???

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Re: Recording, Bit Depth & Sample Rates ???

Postby RichardT » Mon Jul 13, 2020 2:09 pm

MOF wrote:Apple are now asking for the highest bit and sample rate files: “Use High-Resolution Sources.
To take best advantage of our latest encoders, use only 24-bit sources and send us the highest-resolution master file possible, appropriate to the medium and the project. Don’t upsample files to a higher resolution than their original format. Upsampling won’t recover or add information to an audio file. Similarly, don’t “bit-pad” or recapture 16-bit files in 24-bit.
Provide High-Resolution Masters.
Some mastering engineers prefer to control the SRC process by sending already converted files, however we ask that you deliver the highest native sample rate available. As technology advances and bandwidth, storage, battery life, and processor power increase, keeping the highest-resolution masters available in our systems allows for full advantage of future improvements to your or your client’s music”.

Interesting! I think there is a moral problem here about creating hires masters when the samples used are not hires. So for example, if the OP is creating a solo piano piece using Garritan CFX sampled at 44.1kHz, should the masters be released at 96kHz? I would say no, as that suggests the recording was made at that frequency.
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Re: Recording, Bit Depth & Sample Rates ???

Postby merlyn » Mon Jul 13, 2020 2:15 pm

If you find that the sample rate convertor built into your DAW isn't the best you can use Audacity (which is free as in beer and free as in speech), which uses SoX as its SRC, and SoX is good.

When you load up the infinite wave site it's comparing Ableton 10.1 with Acon Digital Acoustica 7.0.5.

ImageAbleton 10

ImageAcon 7

The Ableton 10 sweep graph is what you want -- a white line on a black background that goes up to the Nyquist frequency. Although they are at a very low level the purple background of the Acon graph shows noise and artefacts, so it's not quite as good as Ableton 10. What you absolutely don't want is the Ableton 7 graph :

ImageAbleton 7

This psychedelic mess is beyond belief :lol:

Now if we look at SoX 14.4 VHQ Linear Phase it looks the same as Ableton 10 :

ImageSoX 14.4 VHQ Linear Phase

That's because it is the same -- Ableton 10 uses SoX. Audacity also uses SoX :

ImageAudacity 2.0.3 (Best Quality)

If you look closely you'll see that Audacity doesn't quite go up to the Nyquist frequency -- the line starts to turn red, meaning the amplitude is decreasing. Audacity doesn't use the super steep filter of SoX VHQ. It's good enough and, as the audiophile bashers like to point out -- you can't hear anything up there anyway. :lol:
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Re: Recording, Bit Depth & Sample Rates ???

Postby MOF » Mon Jul 13, 2020 2:31 pm

Interesting! I think there is a moral problem here about creating hires masters when the samples used are not hires. So for example, if the OP is creating a solo piano piece using Garritan CFX sampled at 44.1kHz, should the masters be released at 96kHz? I would say no, as that suggests the recording was made at that frequency.
On the face of it you’re correct, but it’s what you do to the piano (and other instruments) in the higher resolution projects e.g. eq and reverb that will then take advantage of the increased bit and sample rate.
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Re: Recording, Bit Depth & Sample Rates ???

Postby RichardT » Mon Jul 13, 2020 5:36 pm

MOF wrote:
Interesting! I think there is a moral problem here about creating hires masters when the samples used are not hires. So for example, if the OP is creating a solo piano piece using Garritan CFX sampled at 44.1kHz, should the masters be released at 96kHz? I would say no, as that suggests the recording was made at that frequency.
On the face of it you’re correct, but it’s what you do to the piano (and other instruments) in the higher resolution projects e.g. eq and reverb that will then take advantage of the increased bit and sample rate.

Yes, that is true, which is a legitimate argument for going for 96. I decided not to do that, largely because my mastering engineer told me of a project he’d been involved in where he’d been asked to upsample a 44.1k recording to 96k and the record company involved got found out. I work at 96 to get the benefit of better reverb etc, and the mastering is done at 96, but it’s released at 44.1. I think it’s simply a personal choice.
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Re: Recording, Bit Depth & Sample Rates ???

Postby Hugh Robjohns » Mon Jul 13, 2020 6:20 pm

RichardT wrote:...my mastering engineer told me of a project he’d been involved in where he’d been asked to upsample a 44.1k recording to 96k and the record company involved got found out.

The last time I looked, the (UK) magazine, Hifi News (and record review) devoted a couple of pages every month to reviewing 'hi-res' music releases, both on disc and download, including plots illustrating the energy spread across the theoretical bandwidth.

Of the eight or ten reviewed works, there were always one or two that were very obviously just upsampled from 44.1 or 48, and of those which were probably genuinely recorded at high sample rates -- especially those at 192 and 384 and higher -- it was usually quite obvious that there was far more spurious trash and noise than any musically-relevant content in the top half of the bandwidth.

While MOF is right in that any processing to a 44.1/16 source is likely to result in an increased wordlength and, possibly, generation of extra harmonic content, I'm not convinced it would be enough to justify working at a higher sample rate... or wordlength for that matter. In most cases, the source noise floor will tend to dominate and swamp any ultra-low level contributions from other signal processing, and will the buying public really notice low level distortion harmonics above 20kHz?

I generally work at 24/96k when I'm recording high quality sources in nice acoustics... but for material involving my keyboards and electric guitars I don't see any point in going above 44.1k. I do record with 24 bits but only to provide lots of headroom to make the recording hassle-free. The final mix rarely gets anywhere close to exceeding 16 bits of dynamic range...
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Re: Recording, Bit Depth & Sample Rates ???

Postby RichardT » Mon Jul 13, 2020 6:40 pm

Hugh Robjohns wrote:
RichardT wrote:...my mastering engineer told me of a project he’d been involved in where he’d been asked to upsample a 44.1k recording to 96k and the record company involved got found out.

The last time I looked, the (UK) magazine, Hifi News (and record review) devoted a couple of pages every month to reviewing 'hi-res' music releases, both on disc and download, including plots illustrating the energy spread across the theoretical bandwidth.

Of the eight or ten reviewed works, there were always one or two that were very obviously just upsampled from 44.1 or 48, and of those which were probably genuinely recorded at high sample rates -- especially those at 192 and 384 and higher -- it was usually quite obvious that there was far more spurious trash and noise than any musically-relevant content in the top half of the bandwidth.

While MOF is right in that any processing to a 44.1/16 source is likely to result in an increased wordlength and, possibly, generation of extra harmonic content, I'm not convinced it would be enough to justify working at a higher sample rate... or wordlength for that matter. In most cases, the source noise floor will tend to dominate and swamp any ultra-low level contributions from other signal processing, and will the buying public really notice low level distortion harmonics above 20kHz?

I generally work at 24/96k when I'm recording high quality sources in nice acoustics... but for material involving my keyboards and electric guitars I don't see any point in going above 44.1k. I do record with 24 bits but only to provide lots of headroom to make the recording hassle-free. The final mix rarely gets anywhere close to exceeding 16 bits of dynamic range...

Hi Hugh,

I did some blind testing of masters done at 44.1 and 96, and I could reliably tell the difference. Maybe it’s because the mastering process involved DA and AD steps in the processing.
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Re: Recording, Bit Depth & Sample Rates ???

Postby Martin Walker » Wed Jul 15, 2020 2:57 pm

Hugh Robjohns wrote:I generally work at 24/96k when I'm recording high quality sources in nice acoustics... but for material involving my keyboards and electric guitars I don't see any point in going above 44.1k. I do record with 24 bits but only to provide lots of headroom to make the recording hassle-free. The final mix rarely gets anywhere close to exceeding 16 bits of dynamic range...

As most folks here know, I buy loads of digital downloads from Bandcamp in FLAC format, but am amazed at the number of them that are 48kHz/24-bit, or even 96kHz/24-bit.

The first thing I do is convert the files as a batch process in Wavelab to 44.1kHz/16-bit, which makes much better use of my drive space.

I've even noticed a few 'record companies' selling both 16-bit and 24-bit versions of the releases, and charging more for the 24-bit versions :headbang:

If anyone could hear the difference, paying more might make sense, but I maintain that if you CAN hear an improvement in the 24-bit version, then the 16-bit version hasn't been properly dithered ;)


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Re: Recording, Bit Depth & Sample Rates ???

Postby RichardT » Wed Jul 15, 2020 3:31 pm

Martin Walker wrote:
If anyone could hear the difference, paying more might make sense, but I maintain that if you CAN hear an improvement in the 24-bit version, then the 16-bit version hasn't been properly dithered ;)
Martin

I agree with that. The only difference is the level of the noise floor which is already very low with a 16 bit file, as long as its level is even remotely sensible. Personally I can't reliably tell the difference between 44.1 and 96kHz, but I can very occasionally, sometimes on my own material.
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Re: Recording, Bit Depth & Sample Rates ???

Postby desmond » Wed Jul 15, 2020 3:33 pm

RichardT wrote:I did some blind testing of masters done at 44.1 and 96, and I could reliably tell the difference. Maybe it’s because the mastering process involved DA and AD steps in the processing.

Out of interest, what were the key indicators that enabled you to reliably tell the difference?
And were they the same everytime, or different for different material?
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Re: Recording, Bit Depth & Sample Rates ???

Postby RichardT » Wed Jul 15, 2020 3:44 pm

desmond wrote:
RichardT wrote:I did some blind testing of masters done at 44.1 and 96, and I could reliably tell the difference. Maybe it’s because the mastering process involved DA and AD steps in the processing.

Out of interest, what were the key indicators that enabled you to reliably tell the difference?
And were they the same everytime, or different for different material?

All I did was a blind comparison between the masters, swapping between them until I felt I could tell one was better than the other, then choosing that one. I repeated the trial a number of times. So I simply chose the one that sounded 'better' each time without worrying exactly about what was better about it. Sometimes I chose the 44.1 master but mostly I chose the 96.

Prior to doing the trial, though, I had got the impression that there was a slight cold 'edge' on some of the 44.1 masters compared to the 96.
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Re: Recording, Bit Depth & Sample Rates ???

Postby Hugh Robjohns » Wed Jul 15, 2020 3:52 pm

In the absence of any more plausible explanations, I remain reasonably convinced that the 'coldness' is not caused by the loss of ultrasonics, but the addition of low level aliasing distortions due to non-ideal filters...
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Re: Recording, Bit Depth & Sample Rates ???

Postby Martin Walker » Wed Jul 15, 2020 4:01 pm

In other words, better converters would render the difference between 44.1 and 96 kHz audio vanishingly small? ;)


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Re: Recording, Bit Depth & Sample Rates ???

Postby Hugh Robjohns » Wed Jul 15, 2020 5:11 pm

:thumbup:
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Re: Recording, Bit Depth & Sample Rates ???

Postby RichardT » Wed Jul 15, 2020 5:12 pm

Hugh Robjohns wrote:In the absence of any more plausible explanations, I remain reasonably convinced that the 'coldness' is not caused by the loss of ultrasonics, but the addition of low level aliasing distortions due to non-ideal filters...

That's what I tend to think too. I don't believe the ultrasonic signal makes a difference (certainly not to someone like me who is nearly 60).
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