In article op.v0x5r6ockd9x7s@fred, Johny B Good
wrote:
On Sun, 21 Aug 2011 11:58:10 +0100, Jim Lesurf
wrote:

====snip====


FWIW I've seen examples of files that were clearly clipped or madly
compressed, but to a level well below 0dBFS. It would be hard for an
automated system to tell if this was happening, but to the human
eyeball the plots make it clear - as do the ears! :-)


I'm guessing at clipping level of around -3.5db FSD. It's a very
common failing when a PCI or on-board sound card has been used to
digitise analogue sources from the line in socket.

Good estimate. :-)

One example (A track from a 'Franz Ferdinand' CD) has a peak at -3.52dBFS
on one channel and -3.13dBFS on the other. A histogram of the rate of
occurances of various levels has one channel sitting between -3 and -4 dBFS
for about 28 percent of the time! The shape of the distribution looks
almost like the bottom half of a squashed gaussian.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html