Voladj Tryout Worksheet
by Tony Fabris

Requires:
Empeg Car software version 2.0 beta 11 or later (here).
Latest version of Mark Lord's Hijack kernel (here).
Looks best when viewed in Internet Explorer, boxes come out the wrong size in Netscape.

Usage:
  1. Edit the file subframe1.htm and replace all instances of http://empeg with the address of your player.

  2. Use Hijack to look up the FID of your favorite test song on your player. Mine is "La Villa Strangiato". Enter this as the default in subframe1.htm.

  3. Open the Hijack menu and select "Auto Volume Adjust". Leave it on the screen.

  4. Open the file voladj.htm in your web browser.

  5. Mess with the parameters and watch the scale behavior on the player screen. The left and right buttons on the player's front panel will work to skip to the beginning of the song, or to FF/REW, even with the Hijack screen up.

  6. When done, transcribe your values into config.ini.



Parameter 1: Volume Increase Factor Per Second
Default: 0x2000 hexadecimal, 8192 decimal.

This is how quickly the quiet passages get "ramped up". This value is shifted left 16 bits and expressed as an integer. 0x2000 increases the volume by a factor of two per second. Do not set this very high or very low in comparison to the default values, or strange things can happen. An example of valid values would be 0x3000 to increase the volume by a factor of 3 per second, or 0x1800 for a factor of 1.5 per second.
Parameter 2: Minimum Volume
Default: 0x0199 hexadecimal, 409 decimal.

Voladj attempts to make this the quietest thing you hear in units of sample magnitude. To disable voladj completely, set this value to 0. Very high values will confuse the algorithm, so keep it under a few thousand.

Note: More research needed on exactly how this affects the player.
Parameter 3: Headroom
Default: 0x1000 hexadecimal, 4096 decimal.

Meant to prevent hasty adjustments to volume when the clipping limit is reached. Currently ignored by the code, changing it has no effect.

Note: More research needed to verify whether or not it's actually ignored.
Parameter 4: Real Silence
Default: 0x1B hexadecimal, 27 decimal.

Expressed in terms of sample magnitude. Sounds below this level are assumed to be silence or tape hiss. When the music falls below this level, the amplitude will be gradually reduced to normal instead of being gradually increased. For example, if you raise this value to 200 decimal, the software will tend to amplify tape hiss at the ends of songs less frequently.
Parameter 5: Fake Silence
Default: 0x46 hexadecimal, 70 decimal.

Expressed in terms of sample magnitude. Sounds at this level will be increased to Minimum Volume. This value must be greater than Real Silence. Increasing this value has the effect of putting a ceiling on how much a very quiet passage will be amplified. For example, if you increase this to decimal 1000, an extremely quiet instrument buried in tape hiss will not be amplified all the way to the top of the volume scale, but rather will be increased by a more conservative amount.

Config.Ini Syntax
Default values shown.

[hijack]
voladjlow=0x1800,100,0x1000,25,60
voladjmed=0x2000,409,0x1000,27,70
voladjhigh=0x2000,3000,0xc00,30,80