Fix broken links in the man page by pointing to a

source that works or is the new location on the
same page.

Submitted by:	    alfix86_gmail.com
Approved by:	    bcr
Differential Revision:	https://reviews.freebsd.org/D23769

share/man/man4/pcm.4

@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd March 22, 2012
+.Dd May 5, 2020
 .Dt SOUND 4
 .Os
 .Sh NAME
@@ -743,16 +743,16 @@ A device node is not created properly.
 .Xr mixer 8 ,
 .Xr sysctl 8
 .Rs
-.%T "Cookbook formulae for audio EQ biquad filter coefficients, by Robert Bristow-Johnson"
-.%U "http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt"
+.%T "Cookbook formulae for audio EQ biquad filter coefficients (Audio-EQ-Cookbook.txt), by Robert Bristow-Johnson"
+.%U "https://www.musicdsp.org/en/latest/Filters/197-rbj-audio-eq-cookbook.html"
 .Re
 .Rs
 .%T "Julius O'Smith's Digital Audio Resampling"
 .%U "http://ccrma.stanford.edu/~jos/resample/"
 .Re
 .Rs
 .%T "Polynomial Interpolators for High-Quality Resampling of Oversampled Audio, by Olli Niemitalo"
-.%U "http://www.student.oulu.fi/~oniemita/dsp/deip.pdf"
+.%U "http://yehar.com/blog/wp-content/uploads/2009/08/deip.pdf"
 .Re
 .Rs
 .%T "The OSS API"