volume decreasing during playback

[masken]

Got a problem, which I don't think is player-related though.

Playing my movie encoded with XviD - doesn't matter if it's AC3 or MP3, I've tried both - the audio decreases slowly but constantly throughout playback. When I've queued up 2CD's for example, and WMP starts the second CD, the audio jumps up to the "start-level" again. It also does so if I search within the XviD.

Anyone know where I should begin looking for errors?

[jon.schaffer]

Has your player got an option to normalize the audio? Or maybe a filter (dedynamic, AC3Filter)?

If yes, it may apply a realtime dynamic gain to the sound, but if the gain is too strong, in order to prevent from saturation/clipping, this overall gain may be automaticaly decreased, thus the progressive sound volume decreasing during the movie.
When a new movie is opened, the appplied gain is reset to the initial value...

Hope this helps

EDIT:
in general, this "dedynamic" or "gain" option can be disabled or at least modified (ie: you can lower the overall gain)

[masken]

It's just a standard WinXP with the latest WMP and AC3filter. Yeah I know of the AC3filter gain, which is disabled. Funny thing is that it happens with MP3 audio too?

[jon.schaffer]

Originally posted by masken
Funny thing is that it happens with MP3 audio too?
If "MPEG Audio" is set Enabled in AC3Filter options, then AC3Filter is loaded each time a MP3 soundtrack is played... and then all the AC3filter functions are used... (IIRC, AC3Filter does not decode the MP3 soundtrack, but "filters" it).

Go to the AC3filter configuration -> system tab and see when AC3filter is used...

EDIT: are the 2 gain options (gain and DRC disabled)?
[When the gain is used (which seems not to be the case for you), this decreasing volume behavior happens when the One-Pass Normalization is enabled.]