[alsa-devel] wrong decibel data?

[Raymond Yau]

2010/4/6 Nicolo' Chieffo <nicolo.chieffo at gmail.com>

> I've already attached my alsa-info.log in my first post.
>
>
>
> * alsamixer 0 dB (100%):
> Simple mixer control 'Master',0
>  Capabilities: pvolume pswitch pswitch-joined penum
>  Playback channels: Front Left - Front Right
>  Limits: Playback 0 - 65536
>  Mono:
>  Front Left: Playback 64044 [98%] [on]
>  Front Right: Playback 64044 [98%] [on]
>


Most users only care about 0dB point since any software gain is the cause of
clipping (distortion) when the volume control provide software gain


http://en.wikipedia.org/wiki/Clipping_%28audio%29

In digital signal
processing<http://en.wikipedia.org/wiki/Digital_signal_processing>,
clipping occurs when the signal is restricted by the range of a chosen
representation. For example in a system using 16-bit
signed<http://en.wikipedia.org/wiki/Signed-digit_representation>integers,
32767 is the largest positive value that can be represented, and
if during processing the amplitude of the signal is doubled,
sample<http://en.wikipedia.org/wiki/Sample_%28signal%29>values of
32000 should become 64000, but instead they are truncated to the
maximum, 32767.