Thank you Reuben. -Eric Rz. On Wed, Dec 03, 2003 at 11:23:50AM -0600, Reuben Martin wrote: > DC offset is when there is a Direct Current running over the same lines that audio runs through. Since sound signals are a type of Alternating Current, the addition of the DC tends to shift, or offset, the audio signal. > > regards > -Reuben > > -----Original Message----- > From: Eric Dantan Rzewnicki [mailto:rzewnickie@xxxxxxx] > Sent: Wednesday, December 03, 2003 11:10 AM > To: A list for linux audio users > Subject: [linux-audio-user] what is DC? [was Re: Analyzing ogg files] > > > What is DC offset in this context? I've seen this term on this list > before, but don't really understand what it means. > > Is this the same thing refered to by the ecasound options -ezf and -ezx? > > -ezf > Finds the optimal value for DC-adjusting. You can use the result as > a parameter to -ezx effect. > > -ezx:channel-count,delta-ch1,...,delta-chN > Adjusts the signal DC by 'delta-chX', where X is the channel number. > Use -ezf to find the optimal delta values. > > or is that a different DC? > > -Eric Rz. > > On Tue, Dec 02, 2003 at 07:38:54PM -0800, Mark Knecht wrote: > > On Tue, 2003-12-02 at 13:06, Andrew Burgess wrote: > > > >> Is there a DC offset which the cheap card is eating? > > > > > > >A DC offset is an interesting idea. How would I test for that? > > > > > > sox <file> -e stat > > > > > > displays midline amplitude. > > > > > > Or try a highpass filter, just as a test. > > > > > > > More data, but I'm not sure there's an answer there yet. The first file > > creates a very loud glitch sound, which the second one doesn't. The > > midline value seems better on the first, assuming this represents DC > > offset. > > > > bash-2.05b$ sox gmc2.ogg -e stat > > Samples read: 26972160 > > Length (seconds): 305.806803 > > Scaled by: 2147483647.0 > > Maximum amplitude: 0.999969 > > Minimum amplitude: -1.000000 > > Midline amplitude: -0.000015 > > Mean norm: 0.138033 > > Mean amplitude: 0.000003 > > RMS amplitude: 0.189967 > > Maximum delta: 0.959961 > > Minimum delta: 0.000000 > > Mean delta: 0.093997 > > RMS delta: 0.128996 > > Rough frequency: 4766 > > Volume adjustment: 1.000 > > > > bash-2.05b$ sox examplesustain.ogg -e stat > > Samples read: 11361130 > > Length (seconds): 128.810998 > > Scaled by: 2147483647.0 > > Maximum amplitude: 0.649841 > > Minimum amplitude: -0.661896 > > Midline amplitude: -0.006027 > > Mean norm: 0.069344 > > Mean amplitude: 0.002177 > > RMS amplitude: 0.092420 > > Maximum delta: 0.784546 > > Minimum delta: 0.000000 > > Mean delta: 0.072115 > > RMS delta: 0.095279 > > Rough frequency: 7235 > > Volume adjustment: 1.511 > > bash-2.05b$ > >
