Different video files and formats have different audio volume levels. For music files, there is a common technique to compensate for this called Normalize. It basically measures the volume of your songs, and adjusts the volume setting for them to make them all the same volume. With video files, you usually don't play more than one movie or a few episodes, so there really is no easy way to "normalize" the volume, because there are no other videos to compare it with.
If you convert from a DVD without adjusting anything of the volume, the audio tends to be pretty soft. If you convert from a pre-ripped file that already has the volume adjusted, it will sound a lot louder, but if you convert a mixture of DVDs and video files, you continuously have to adjust the volume adjustment setting in order to compensate for the loudness. Either by modifying the volume in the conversion tool, or when you are actually watching video on your device. (remember those extremely loud commercials while watching a movie on cable?)
So, because of this, I came up with "Volume Maximizer" (unique to only dvdcat4)
It works similar to the "Normalize" technique, but because there are no other videos to compare it with, it uses a loudness level.
Regardless of what the volume of the original video is, the volume will be adjusted to peak at the selected maximum setting, so whatever you convert will have the same volume.
To show what the “Volume Maximizer” actually does, I created 3 5 minute audio clips (Audio only > MP3 in DVD Catalyst 4) using 3 different settings.
For visualization, I used a free program called Audacity, which displays a nice graph.
First I turned off the Volume Maximizer setting (Global Settings > Advanced), and reduced the volume adjustment setting in “Modify” to 0 to give you an indication of the volume from a standard DVD (V for Vendetta to be exact)
The 2 blue lines in the screen-shot represent the actual volume levels of the beginning of the movie. The maximum volume without causing distortion is represented by the 1 and -1 at the top and bottom of each gray area. As you can tell, there is plenty of room left to spare.
Next, we left the volume maximizer setting turned off, but in “Modify” we increased the volume to 5:
As you can tell from the screenshot, the volume is much better (the blue area is closer to the 1 and -1) , than without the adjustment, but still there is a lot room left for improvement. If you are converting a video file that already has increased volume (most of them to be honest) the volume will be boosted even more, because everything the conversion tool converts will receive the same volume adjustment.
Next we turned on the Volume Maximizer setting (since it overrides the volume in “Modify” you can leave that as is)
As you can tell from the screen-shot, the volume levels are improved considerably. There is still some room left, but this is because of the safe-setting used for the volume maximizer. If you do increase it even more, you will likely experience distortion of the sound during loud explosions and things like that. Now if you convert a volume-modified video file, it will also be boosted to the maximum selected setting, regardless of the volume level it already has. Even performing a double-conversion (not recommended due to quality-loss) the volume will still have the same loudness.
In short, the Volume Maximizer feature makes sure that all your conversions have their volume level boosted to the same loudness, eliminating the need to manually adjust the volume on your Xoom (or other device), or to set the volume to the maximum setting (and then turn deaf after you get a new email notification).