Tempo/Pitch issue

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kelleydv
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I'm not sure how it happened, but I opened a project I haven't worked on for a while, and it's all slowed down and tuned down...

Why might this happen?

I tried changing the tempo of the project and that did nothing. I'm pretty sure the tempo is where I originally set it when I recorded the audio.

linuxdsp
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Check your sample rate settings

kelleydv
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@linuxdsp
Duh! Thanks. That was it. I was playing around with 48khz when I recorded this project, and Jack was running in 44.1.

On a related note, what do I really get for recording at higher sample rates?

kelleydv
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I'll also mention that Ardour has usually warned me in the past when the sample rates don't match, but not anymore on this project for some reason. It warned me just now when I opened a project recorded in 44.1kHz while running in 48

seablade
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Heh what you get for higher sample rates is always a fun topic. Ill put it this way, I still often record at 48k and 44.1k depending on my end destination. You do get some benefit from 96k and 88.2k respectively, primarily when dealing with dsp processes as some might sound better at the higher sample rates, beyond that you won't hear to much of a difference. Going to 192k I personally believe in most cases is pointless.

So the majority of projects I record still I record at 44.1 and 48k. I am far more worried about making sure I am recording 24bit than at a high sample rate. There are some projects I will do at a high sample rate(96k) however though, in many cases it is more a reasoning of, there is little reason for me not to on this project.

In as far as the warning on open at 44.1 and 48, it is most likely you opened the project at the wrong sample rate and saved it at the wrong sample rate, which I believe will cause what you described IIRC.

Seablade

kelleydv
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Hey, thanks seablade.

What is actually going on (conceptually) with sample rate and bit depth? You seem to be saying that 24 bit makes a bigger difference compared to higher sample rates. I've noticed that cd's are 16-bit standard. Logic has a 24-bit default setting for audio...

Does it make a difference if I am going to put something to cd in the end? Does it make a difference as to how the dsp of arbitrary plugins, etc., behave?

I'm interested in your thoughts, and especially your (aural) experience.

seablade
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24 bit is desirable for recording, but isn't necessarily needed for delivery. It is desirable for recording as it allows you to capture with a lower noise floor compared to 16 bit, which allows you to turn down your gain a bit. It used to be to get a good clean recording in 16 Bit, you would have to set the gain to within 3dB of 0dBFS for the peaks on your source, which meant that you were susceptible to occasional overages(clipping) and would have to redo your recording. With a 24 Bit recording, because it is capable of capturing more detail in levels of very quiet sounds, your noise floor is typically lower allowing you to capture at -12dBfs to -20dBFS without fear of noise floor becoming an issue later resulting in less chance of overages.

Seablade

Simplifying noise floor as it relates to bit-depth slightly, but the main point is there.

anahata
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Higher sampling rates can improve the sound from non-linear processing such as distortion plugins, compressors and limiters. The reason for this is that their processing can introduce products above the Nyquist frequency which get aliased into the audible range. Moving the SR and hence Nyquist frequency up reduces the amount of such interference.

Having said that, the better quality plugins do internal oversampling anyway in order to reduce this problem.

I'm routinely recording at 24/48 and usually exporting to 16/44.1

Seablade is spot on about 24 bit, as I would expect of course.

kelleydv
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I've been playing with this, thanks for the helpful info.