View Single Post
Old 5th August 2014, 12:39   #7  |  Link
hello_hello
Registered User
 
Join Date: Mar 2011
Posts: 4,823
Quote:
Originally Posted by LoRd_MuldeR View Post
This would be the case, if we simply calculated the maximum possible gain factor for each frame and then applied that gain factor to the frame - which would result in strong and unsteady gain fluctuations. The Dynamic Audio Normalizer mostly avoids the "pumping" problem by looking at a certain neighborhood around each frame rather than individual frames. Think of it like a sliding window approach. First, a minimum filter is applied, which is pretty effective in filtering out short-term gain variations. Secondly, a Gaussian smoothing kernel is applied, which ensures the remaining gain changes are smooth and steady. If you still get noticeable "pumping" after all, you should probably try a larger window size...
I'm no expert on this, but isn't there always some sort of compromise between reducing the "pumping" effect, and the amount of time over which the volume is adjusted, in respect to how much you can "compress"?

I've had a brief play with the DynamicAudioNormalizer (this isn't a criticism as it seems to work well) but the default frame length of 500ms seems too large to me. At least for "soundtrack" audio.

So I had a look at my RockSteady settings and it's RSM window (which I guess is it's name for "frame length") defaults to 75ms, so I added --frame-len 75 to the commandline along with --gauss-size 11 and so far I much prefer the result, at least for stereo "soundtrack" audio. For example, when going from a loud peak to relative silence with dialogue, the default settings take too long to increase the level of the dialogue for me, whereas with the smaller frame length the dialogue seemed to commence with full amplification. Admittedly if you listen closely the really quiet background stuff behind dialogue is on the verge of "pumping" at times, but it still sounds good to me. And it's definitely better than my TV's "night mode" which does cause audible "pumping".

Anyway, each to their own.... thanks for quite a nice audio utility.

Last edited by hello_hello; 5th August 2014 at 12:41.
hello_hello is offline   Reply With Quote