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Clock Speed/Bit rate issue


amoscochran

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Hey everyone!

 

I am working on some radio spots for a company and their sound guys is new to things and we ran into an issue of my music playing faster than it should on his end of things. I recorded things in 48kHz clock speed and bounced at 24 bit. What all do I need to change to fix this problem? Do I need to bounce in 16 bit? Change clock speed to 4.41kHz?

 

Any advice would be great! I have to have these done by morning!

 

Thanks,

 

amos

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Chances are that the files need to be at 44.1K. However, your best bet is to ask the sound guy what he needs spec-wise. Only he can give you a definitive answer as to what your deliverables need to be. And if he doesn't know, it's his job to find out from someone who does. But if he's clueless, send him a 44.1K/24 bit file and see if that works. If so, you've answered his questions and you're the hero.

 

16 bit v. 24 bit is a measure of bit depth, not bit rate. The bit depth will no effect on the rate at which the files play back. Only the sample rate will.

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@ski Thanks so much for your thoughts! I did some test bounces, changing to 4.41 in the bounce down options. I was able to drop that file into itunes and play it. The 48kHz would not go into Itunes. Hopefully that will fix things. The sound guys I am working with is very new at this and it is not his field so I am kind of on my own to figure it all out. Thanks again!
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Hmmm If the audio is speeding up and pitching up on his side of things then it appears that he is trying to play your file at a higher sample rate than the audio file. If your audio is at 48khz then he must be playing it back at 88.2khz or 96khz. or maybe even higher. How much faster and higher is it playing? If he were playing it back at 96khz then it would be twice as fast. (double the sample rate)
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@ski Thanks so much for your thoughts! I did some test bounces, changing to 4.41 in the bounce down options. I was able to drop that file into itunes and play it. The 48kHz would not go into Itunes. Hopefully that will fix things. The sound guys I am working with is very new at this and it is not his field so I am kind of on my own to figure it all out. Thanks again!

 

Here's what I'd do if this were me and I was working with someone who was (essentially) clueless on the client end. I'd call him on the phone and ask him to play the file over the phone so I could hear what he's hearing. If the pitch was significantly higher, then I'd assume (as jtees suggested) that the sample rate of your deliverables would have to be at 88.2 or 96. However, I'd say that it's highly unlikely that they're working at one of those rates, because neither one is standard and very few people are ever expected to deliver files at 88.2 or 96 for radio broadcast AFAIA.

 

But if they're playing back your 48K file at 44.1K, then the pitch you'd hear as he plays it back would be LOWER, not higher. So who knows, maybe they are running at 88.2 or 96. Or maybe the sound guy is so clueless that he's taking your files which are perfectly fine and screwing something up.

 

Coming back full circle, call the guy and have him give you playback over the phone, and take it from there.

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Fantastic thoughts from both of you. We are talking in the morning to figure everything out. I will have him play them over the phone. I figured it was playing faster because of a specific "ding" that is in the music. He said it happening way before it should on his end.

 

The only reason I even changed over to 48kHz is because the voice over files he sent me to work from were in 48kHz. I went ahead and switched over thinking that was what I needed to do. As I mentioned- in the bounce down options I have switched to 4.41kHz to see if that matters on his end. If something is recorded at 48kHz and then changed to 4.41kHz in the bounce down, does that effect anything? When listening back it did not seem to make a difference. All the parts were MIDI except for bass, which was a real instrument.

 

I will for sure have learned a bit from all of this. Thank you both again!

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It's natural to assume that if the files he sent you were at 48K that you'd want to stay at that sample rate. However, you can't always assume, unfortunately. And FWIW, mistakes get made all the time along these lines in digital music production. For example, I once sent a bunch of 48K music stems to a percussionist to do overdubs on. His engineer laid up my files in ProTools, and apparently didn't check the sample rate and played them back at 44.1K, as it was later revealed. Well, playing back 48K tracks at 44.1K sample rate lowers the pitch and the tempo, and it's at that tempo (whatever it ended up being) that the percussionist played to. So it was no wonder that when I laid up the percussionist's parts in my session, they didn't play in sync. In short, everything they did was a wash.

 

So here, a world-class engineer made a hugely rookie mistake in assuming what the sample rate should have been without checking. I'm spinning this yarn to point out that these kinds of mistakes get made even by experienced people.

 

So for the future, the best approach you can take is to confirm with the client what sample rate and bit depth they're expecting you to deliver (hence the term "deliverables") before you get started. Now that's not to suggest that you were wrong in working at 48K. I think you'll have a much better idea of what's going on after you confer with the sound guy again.

 

Now, on to sample rate...

 

If you take a 48K project, bounce it out as 44.1K, and then play it back in QuickTime or iTunes, it's going to sound normal because the Mac OS has realtime sample rate conversion. However, if you were to have laid up that 44.1K bounce in your 48K session, you would have undoubtedly heard the difference.

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I do think it is always nice to learn something new on each gig. The hard part about this is the fella mixing the spots is very new to this and it is not his field. He more or less was stuck with the job. It will all work out.

 

I am wondering/hoping if I bounce my tracks down and change to 44.1 in the bounce options that it will play correctly on his end. If all else fails I can redo the spots fairly quick at 44.1 in a new project. I would just like to avoid that. Again, thank you for all your thoughts. Knowing the logic forum is out there always makes problems easier to deal with.

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I am wondering/hoping if I bounce my tracks down and change to 44.1 in the bounce options that it will play correctly on his end.

 

All you can do is try and send them along. If they sound right on his end then you'll at least make your deadline.

 

If all else fails I can redo the spots fairly quick at 44.1 in a new project. I would just like to avoid that.

 

You shouldn't need to redo the spots at 44.1. Just keep them at 48K and bounce them out at 44.1. Then, to be absolutely sure they sound right (and they will), close out your projects, open a new entirely blank project. Set it to 44.1 and lay up your bounces. They should sound perfect.

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