Avid Pro Audio Community

Avid Pro Audio Community

How to Join & Post  •  Community Terms of Use  •  Help Us Help You

Knowledge Base Search  •  Community Search  •  Learn & Support


Avid Home Page

Go Back   Avid Pro Audio Community > Pro Tools Post Production > Post - Surround - Video

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 04-29-2008, 07:53 PM
vudoo vudoo is offline
Member
 
Join Date: Jan 2001
Location: Montreal, Quebec, Canada
Posts: 937
Default AC3 pumping on playback..help

I use Compressor to encode my final mix ( stereo 48Khz/16 bits ) to Dolby AC3 ( 192 Kbits ) and burnt a DVD ( video stream encoded at proper bit rate ). I've done this a million times and have quite a bit of experience with DVD authoring.
When i playback the DVD via my MacBook Pro, the volume changes drastically in certain spot ( pumping effect ). I've come across this similar problem before with commercial DVD and by Enabling the '' Disable Dolby dynamic range compression '' option in the player preferences cured the problem but this time it seems to do nothing....any suggestions ??? Thanks
Reply With Quote
  #2  
Old 04-29-2008, 10:10 PM
jim a jim a is offline
Member
 
Join Date: Mar 2008
Posts: 4
Default Re: AC3 pumping on playback..help

Quote:
...When i playback the DVD via my MacBook Pro, the volume changes drastically in certain spot ( pumping effect ).
If it is ON, try turning the RF Pre-Emphasis Filter (RF Overmodulation
Protection) OFF. ON will trigger a really ugly protection limiter in the
decoder if the levels are too hot, and this cannot be disabled.

Also, if the RMS level reaches -11dBFS or so, you're starting to hit the
built in compressor hard no matter what you turn off. I find that -17 to
-16dBFS RMS is about max to have a chance of sounding good, but this
is dependent on content. As always YMMV.

-Jim Atkins
Reply With Quote
  #3  
Old 04-30-2008, 07:38 AM
vudoo vudoo is offline
Member
 
Join Date: Jan 2001
Location: Montreal, Quebec, Canada
Posts: 937
Default Re: AC3 pumping on playback..help

Jim,

The '' RF Overmodulation Protection '' is off by default in Compressor. I get commercial music DVDs mixed very loud, easily hitting - 3 to 0.2 DBfs...how do they manage to encode to AC3 without the pumping effect in this case ??
Reply With Quote
  #4  
Old 04-30-2008, 12:37 PM
Mubeau Mubeau is offline
Member
 
Join Date: Jun 2005
Location: Mid- Europe
Posts: 359
Default Re: AC3 pumping on playback..help

deactivate:
a) "AGC" and use "no compression" setting instead of "film standard...."
b) RF overmodulation
c) also deactivate all other "preprocessing" except: 90° phaseshift.
by saying this: if you do so, do your LFE band pass by yourself, but do it!

at least: never had problems so far for DVD, but I hate dolby for AC3

be arware that there are still some DVD players (especially software solutions!!!!)
which do some very interesting things to your audio...

best.m.
Reply With Quote
  #5  
Old 04-30-2008, 12:47 PM
jim a jim a is offline
Member
 
Join Date: Mar 2008
Posts: 4
Default Re: AC3 pumping on playback..help

Hmm... for loudest playback the important bits are:

dialnorm = -31
Dynamic Range Compression = none
RF Pre-Emphasis Filter = off

Mixing Level and Room Type are not used by the decoder but may be
seen by downstream devices and could have some effect with some
devices.

The encoder can also insert metadata to activate a limiter in the
decoder to prevent overload on downmixing. This is most active if
you have strongly correlated material in multiple channels.

To get a feel for the compression and limiting you can't control,
switch between 'Line Mode' and 'Custom' (set Cut and Boost to 0)
on a professional decoder. Consumer devices usually have only
Line and RF modes.

-Jim
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Getting that punchy, pumping kick sound DonaldM The Drum Room 11 11-25-2011 09:19 PM
Pumping Effect On Bounced Mix darko909 Pro Tools M-Powered (Win) 0 02-02-2011 12:05 PM
Pumping in Dynamics III yin7yang64 003, Mbox 2, Digi 002, original Mbox, Digi 001 (Mac) 3 04-25-2007 08:26 AM
pumping sound lonestarparis 003, Mbox 2, Digi 002, original Mbox, Digi 001 (Mac) 8 12-01-2004 01:42 PM
Digi pumping out more low $$ toys clarpark Pro Tools TDM Systems (Mac) 9 05-29-2003 10:05 AM


All times are GMT -7. The time now is 11:54 AM.


Powered by: vBulletin, Copyright ©2000 - 2008, Jelsoft Enterprises Limited. Forum Hosted By: URLJet.com