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Hello.

Maybe this question has already answered itself as I'm not quite sure how else it would be done. But say I'm recording sound effects for distribution and I want to offer them in different variants... 24bit 96khz, 24bit 48khz and 16bit 44.1khz.

Is it absolute common practice to record in the highest possible format and then dither down to the others? ...or do pros record the sound at different formats each (which I can't really see how this is done)

With this, is there anything I should note when preforming dithering on such material? The dither options available to me are iZotope's 64-bit SRC and MBIT+.

Many thanks.

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Always record at the highest bit depth you can, so you have the best dynamic range to work with. After you've mixed and gotten the levels right, then you can convert to 16-bit/44.1 kHz for end users. Playback at anything higher than 48 kHz decreases fidelity while doubling file size. (If you're distributing sound effects to be re-used by others, then this doesn't apply, you should stay at the higher sample rate, and the re-users should downsample.)

Dithering is used when converting to a lower bit depth. It decreases nasty things like quantization distortion by increasing the overall noise a little bit.

As for sampling frequency, I'd record at 88.2. It's not a matter of recording what humans can hear; 44.1 is plenty for that. Instead, it's a matter of avoiding aliasing. All converters have some amount of aliasing. Recording at a higher sampling rate ensures that the aliasing stays way up in the ultrasound, and then you can get rid of the ultrasound with a really good digital filter on the computer instead of the reasonably good digital filter in the oversampling ADC. (Also software monitoring latency is lower at higher sample rates.)

In my experience, ADCs have higher noise when recording at higher sample rates, and it provides no benefits unless you're intentionally trying to record ultrasound, so don't go any higher than 88.2/96. (Also see this argument that the optimal sample rate is around 60 kHz.)

And 88.2 instead of 96 because 88.2 is a perfect multiple of 44.1. To downsample, you just do the digital filter and then drop half the samples. To convert 96 to 44.1, you need to, uh... do more than that. I'm sure they don't literally oversample by 147x and then downsample by 320x, but that's effectively what the algorithm is doing. It's more complicated than 88.2, so the processing will take longer, even if the converter is designed well enough to get the same output quality, so I see no benefit to 96.

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    where are the sounds targeted at? if for the music market 88.2k makes sense but not for sound post where 48k and 96k are most commonly used... 44.1kHz sound effects is just a throwback to CD distribution – user49 Aug 14 '10 at 23:47
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    plus, you're not going to get many sales if you distribute at 44.1K IMHO because I consider that a bit amateurish - look at Tim's, Chuck's and other online distributors - their top sample rates at 96K and you should do the same if only for the competition. – Utopia Aug 15 '10 at 20:47
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    @Utopia For playback, anything over 48 kHz is harmful, not helpful. File size is increased and fidelity is decreased, due to distortion in speakers trying to reproduce ultrasound. people.xiph.org/~xiphmont/demo/neil-young.html#toc_1ch – endolith Jan 30 '14 at 17:37
  • i recently read that, rather thoroughly written article, however I would like to do some testing myself before accepting 96khz is bad for fidelity. Have you tested this and what are you experiences. But besides fidelity there's also the factor of pitch shifting with 96khz files that sounds way better than with 48khz files, a good reason to sample at 96 or higher if the material 'needs' that. – Arnoud Traa Jan 30 '14 at 19:09
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    @endolith "For playback, anything over 48 kHz is harmful, not helpful" - this statement is wrong under certain circumstances; the OP specifically says his sounds are sound effects being recorded for distribution. So it is about how those sounds will be used, a sound effects editor or sound designer is doing a lot more than just playing the sounds – user49 Jan 31 '14 at 21:30
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You should always record at the highest possible settings (imho). I see no reason not to since storage is so cheap these days, plus you're future-proofing your library as well as technology allows.

Regarding dithering, I personally don't do anything special in that regard when mastering my recordings. I simply clean them up, apply any corrective EQ and/or compression, and save them down to the desired bit/sample rates. That's it! Keep it clean for unknown future purposes.

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I believe this article sums it up far better than I ever could. And I like it because it doesn't seem to lean to either side of the "sample rate war". I recommend everyone read it of you have the time.

http://www.trustmeimascientist.com/2013/02/04/the-science-of-sample-rates-when-higher-is-better-and-when-it-isnt/

From my personal experience, record at 24bit 96k for marketing reasons. Whether or not there's a true benefit means little when that's what the customer wants. And then dither down from there if needed.

And one point made in the linked article I fully support is the use of higher sample rates in the case of inferior electronics in cheaper converters. (Corners have to be cut to make those boxes cheaper). The basic premise, the expensive converters can give better sound at lower sample rates. So if you have a cheaper converter, record at higher same rates to allow the frequencies we CAN hear to sound better (or more accurate). Reasons for this explained in the article.

Again, to answer your question specifically, record high and dither.

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After some considerable looking around on the womb and gearslutz, the shared knowledge there seems to be that recording at 44.1khz is just fine (especially if you're going to be bringing it back to 44.1 for CD), though if you've got enough processing power, mixing at 88.2 offers some benefits as when using plugins, "the maths works better". Bit depth of 24 is important mind. ;) Best, Rich @thehuxcapacitor

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    @Rich - 44.1 and it's multiples are fine for CD audio, but more and more effects distributed on CD are being stored as data files. 44.1 is a Redbook Audio CD spec. 48khz is the standard for video/film/DVD. You're better off recording in multiples of this (96, 192), because the ratios work out better when dropping in sample resolution than say 88.2 down to 48. – Shaun Farley Aug 13 '10 at 11:20
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A key thing to understand is that post-CD/DVD, you may not be the one who is making the file that the listener gets. The music or video service does that, because the listeners may not all be getting the same format.

If you submit your masters to iTunes, they want the 24/96 master. From the Mastered for iTunes guide:

An ideal master will have 24-bit 96kHz resolution. These files contain more detail from which our encoders can create more accurate encodes.

That is because they use the 24/96 master as a template for all other formats. Right now (early 2016) they ship a 16-bit 44.1kHz AAC to customers, but at some point in the future they will bump that up, using the same 24/96 master of your song, and likely ship multiple formats.

If you’re publishing on Bandcamp, this is from their Uploading guide:

Why the WAV/AIFF/FLAC upload requirement? Why don’t you just accept MP3s? It’s all about maximizing flexibility for you and your fans. WAV, AIFF and FLAC are high-fidelity (lossless) formats. By starting with the highest possible quality source, we’re able to convert your tracks into a bunch of different format and quality combinations …

Can I upload my 24-bit tracks? You bet. Your 24-bit and 16-bit tunes are welcome, and lossless file downloads (FLAC or ALAC) will always have the same bit-depth as the originals you upload.

So not only does Bandcamp want you to upload a lossless 24-bit file, they can distribute your 24-bit audio to listeners right now.

Other services will also move to this model if they are not there already. YouTube has been doing it for video for years. They will take one 4K video from you and make a bunch of encodes at different sizes and bitrates and give viewers the right one for their situation, based on playback resolution and bandwidth.

So if your recording system can do 24 channels of 24/96 without failing you in some major way, you should definitely record, mix, and master in 24/96, as though no other format existed. Because you can’t know what format the listeners will ultimately get, both today and in the near future. You just need to be concerned with capturing and creating as much quality as possible when you are recording, mixing, and mastering.

If you can’t do 24/96 without reducing your channels too much then fallback to 24-bit 44.1kHz so that at least you aren’t doing sample rate conversion to generate 16-bit 44.1kHz.

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