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I'm trying to bounce out some samples from pro tools at very low sample rates (8khz or 11.025khz) to save ram on a computer game as the frequencys in the samples i'm using don't require a higher sample rate to sound good.

I can get these to loop seamlessly in pro tools but once I bounce them out they are always popping on the loop in the final sample.

Anyone got any tips how to stop this from happening after the bounce? I've made tons of loops for games at higher sample rates but these are being a pain!

thanks!

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4 Answers

So if you open the converted files in a sample editor and zoom right in do they start and end on the baseline? If not, can you just add a small fade to solve it.

I always use a dedicated editor (like Audition or Soundforge) to double check. In fact I'd always bounce out of Pro tools as a .wav in whatever sample rate the session is at and convert after - Pro Tools doesn't support many file types anyway so I got into the habit because of that. It's also nice to have a wav around if you need to provide another type.

8khz is pretty extreme though, you're not getting any frequencies above 4k there and it may be this lowpass filtering which is causing the problem as you're changing the sound drastically. What filetype are you providing anyway?

Also, select convert after bounce in Pro Tools as this is (apparently) more accurate. I've never done any tests myself though...

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I may have to get audition out as you say. 8khz is very extreme but in this instance works surprisingly well. It's .wav. i do convert after bounce for what it's worth. Thing is pro tools makes you fade up at least 4 samples and this is enough to make an inconsistant gap in this particular sample. and cutting on the zero line also seems to make no difference. I will try audition. THanks! –  bob Aug 10 '12 at 18:14
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My guess is that you're ending up with a waveform that doesn't start/end/both at a zero crossing once it recalculates the waveform for the output sample rate. Have you tried putting in a really short fade (either with Cmd+F or volume automation)?

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I have but due to the samples tone even a 4 sample fade up leaves a pop or a inconsistant break in the sound. :( –  bob Aug 10 '12 at 15:35
    
it would need to be more than a 4 sample fade. keep in mind how many samples you're ditching when when you go from 48/44.1 down to 11.025/8. –  Shaun Farley Aug 10 '12 at 18:51
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It's also prudent to check your original file for DC off-set before looping & sample convert . Convertors seem to handle this in different ways.

Though, as Mark mentioned, I too suspect the radically altered freq. content after conversion would require it's loop points to be readjusted. I have run into problems with just a 48kHz > 44.1 convert using spectrally dense material.

It might be good to try another (or several) programs convert process to compare, as I've experienced distinct variations in how they handle the sonic differences after convert - even between different versions of the same program...

good luck! r

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hi

ProTools has a 'bad behavior' here: If you bounce or mix down something, you always have some blank offset on the beginning at the file from about half a frame or more and also at the end! Normally you don't realize this, but if you need to loop something or adding something seamless, it crackles because there is a digital-zero space. I realized that as I have prepared my ambience tracks which should be combined seamless (Part 1 and Part 2 files) for example: https://www.soundeffects.ch/surround-sound-effects-_e.php?soundeffects=munich+city+place It always crackle if I add them and I didn't know why. If you zoom into the file, you'll find the blank offset at start and end.

It took a long time to realize that it's not a mistake on my site, it's ProTools! I have contacted Digidesign about that and they told me something weird about 'how should PT know what you bounce if it just starts?? - I think, of coure it knows, the original file starts at 01:00:00.00 and not at 01:00:00.02. Every cheeper software can handle this but not PT.

If I mixdown files, I make offset at the beginning and end and cut it out destructive. It's more work and not a nice workflow.

best

guido

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@Guido Helbling I noticed the same when bouncing. however if you use shift cmd K to export region as sound file then Protools doesn't add the buffer at the beginning and end of file. –  RedSonic01 Aug 11 '12 at 13:36
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