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Old 02-20-2009, 10:08 AM
muks muks is offline
Join Date: Nov 2007
Location: Warsaw, PL
Posts: 25
Default Peak level changed after sample rate convertion

Hi Guys,

I had a really strange PT behaviour today. I was making and advertisment - limiting my master channel to -9 dB - the session was 44.1 kHz, 24 bit - i just wanted to bounce the session to a stereo file 48 kHz, 16 bit. When i checked the level after bouncing it was at -6.4 dB (checked with DIGI GAIN). I thought there could be something wrong with my master channel - so I hit delete - and created an AUX channel and routed all of my tracks on it, limited to -9 dB, routed it to another audio track and just recorded it. Having checked the level twice - it was -9dB, i exported the region to file (cmd+shift+k) and then checked the level(in another session 48 kHz, 16 bit, and in sound forge) - again -6.4 dB. When i imported that file to my advertisment session the level Was at -8.9 dB. What is going on? Had anybody the same problem?

PS: Offcourse all of the levels are peak levels. I double checked that I Was exporting a stereo file - not multiple mono.

MAC PRO, Tiger 10.4.9, PT HD2 7.4 cs8 with 96 IO, Control 8, Waves Platinium
Impossible to see the future is.
MBP 2.5 /4GB RAM, Mbox2 Mini, PT 9, OS 10.6.8
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Old 02-20-2009, 11:19 AM
StudioRhythm StudioRhythm is offline
Join Date: Apr 2006
Location: California
Posts: 247
Default Re: Peak level changed after sample rate convertion

This is normal -- when you sample rate convert you will always have different peak levels, sometimes lower, sometimes higher. Google "intersample peaks" for detailed info on why.... This is the reason why you should leave more headroom than your peak meters show in digital -- I believe that 6dB of headroom will guarantee you won't have intersample clipping problems upon reconstruction.
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