-
Premiere CS5.5 audio-levels for h264-files and YouTube
Hello there,
I just encountered a problem with audio clipping when rendering a movie from Premiere CS5.5 and uploading it on YouTube.
What I did:
I mixed audio (voice + music) directly in Premiere and used Dynamics (Compressor+Limiter) on the Master track to constrain it to 0dB. From Premiere, I rendered a QT Animation, and then from QT Pro, I rendered a .mp4 with h.264 and AAC. Now the final .mp4 file plays fine in QT and Windows Media Player. But both VLC and YouTube raise the audio levels by ~3dB which results in dirty clipping, of course.What I find really strange is that the same workflow went well for the last projects I did: 0dB level in Premiere, then Premiere -> .mov, then QT Pro -> .mp4 -> YouTube. No clipping for the others, the only difference is that I didn’t do the audio mixing directly in Premiere.
Any ideas? Why do QuickTime and VLC play on a different audio level? How would you check the actual audio level of the final .mp4 file?
-
4 Replies
-
As a good practice you should mix for a nominal level of -6dB instead of 0. Digital is not as forgiving as analog and use of compression and limiters affect the digital signal a little differently than analog. If you are mixing for loudness apply a tad bit more compression to lessen the dynamic range but don’t push to close to the digital limit because once you go over you can never get it back. That includes whatever happens with post processing. Give yourself some headroom.
“Think of everything in terms of building capacity.”
Kris Merkel
twitter: @kris_merkel
Product Manager, Flanders Scientific Inc.
http://www.shopfsi.com
Co-Founder, Atlanta Cutters Post Production User Group
http://www.atlantacutters.com2.2Ghz MBP core i7
16Gb RAM
CS6/FCP7
AJA T-Tap
AJA IO XT
FSI LM-2461W/CM-170W
-
That’s a good point, but not the problem here though. For YouTube and for spreading the video via sharing / USB-Sticks and so on, I prefer the end file being leveled to 0dB. But as I said, in QuickTime and Windows Media Player, the final 0dB mp4-file plays just fine. On YouTube and VLC (with the VLC volume slider at 100%) it starts clipping. And this did not happen until now, although this has been my workflow for several projects now.
For the next project, I will keep your advice in mind and mix everything to -6dB during production. What would you suggest for a final file then? For media like YouTube and PC files, would you still keep it at -6dB or would you raise it?
-
Maxing out your audio at 0dB is not a good idea for digital files because there is no headroom for postprocessing. Always leave headroom.
“Think of everything in terms of building capacity.”
Kris Merkel
twitter: @kris_merkel
Product Manager, Flanders Scientific Inc.
http://www.shopfsi.com
Co-Founder, Atlanta Cutters Post Production User Group
http://www.atlantacutters.com2.2Ghz MBP core i7
16Gb RAM
CS6/FCP7
AJA T-Tap
AJA IO XT
FSI LM-2461W/CM-170W
-
As I said, that’s what I’m going to do for the next projects. But for the final file (no more processing is done on it), I mean the file that I spread among customers who may watch the file on a laptop or mobile phone without headphones, I prefer to give them the maximum volume.
By the way, I figured out the problem: it was a mono/stereo-mismatch. I had a QT Animation file with 2 channels, and when rendering out a mono .mp4 file, QuickTime somehow messed up the overall volume. The final file was playing fine in QuickTime as well as Windows Media Player, but the same file clipped in VLC and on YouTube after uploading.
Reply to this Discussion! Login or Sign Up