ffdshow Audio Normalization

[goldensun87]

Ok, so I'm experimenting with ffdshow's numerous filters. I am curious, what is the ideal "max amplification" for the normalization filter? The default setting in ffdshow is 400%. Should I lower it, increase it, or leave it as is? Also, which other audio filters might combine well with normalization?

[pandy]

there is no ideal parameter - 400% means 4x times louder means 12dB ie level will be amplified max 12dB but not more - so if the input level signal is like -20dBFS after normalization - it will be -8dBFS - key is not go higher than 0dBFS (which is not true - 0dBFS is safe only with very limited types of signals) - safe level is like -6dBFS (-6.02dBFS).
As processing is made usually at more than 16 bits (at least 24 integer) then normalization should be final step (it is a bit like color number reduction or dithering in image processing) - purpose of the normalization is to use all potential dynamics of the reproduction system with some safe margins.

Default 12dB is quite safe value - IMO You can try go up to the 20dB (ie 1000%)

[tebasuna51]

The ideal, for the best quality output, is don't use ffdshow Normalization.

A correct Normalization need 2 pass, first found the max peak value, after amplify all the audio with the same value.
A normalization on the fly can have problems when there are abrupt changes between low and high volumes.

[TinTime]

safe level is like -6dBFS (-6.02dBFS)...

...Default 12dB is quite safe value - IMO You can try go up to the 20dB (ie 1000%)

Do you know if setting Max amplification to 12dB (or 20dB or whatever) and then settting the Master volume to, say, -6dB would achieve this in ffdshow?

tebasuna51's warning about 1 pass normalization aside of course.