anchor.diff:  
   (defun get-layer-string (layer) (nth layer '("Reserved" "Layer III" "Layer II" "Layer I")))
   
  +;;; the modes
   (defconstant +channel-mode-stereo+ 0)
   (defconstant +channel-mode-joint+  1)
   (defconstant +channel-mode-dual+   2)
   (defconstant +channel-mode-mono+   3)
   (defun get-channel-mode-string (mode)  (nth mode '("Stereo" "Joint" "Dual" "Mono")))
   
  +;;; the emphases
   (defconstant +emphasis-none+     0)
   (defconstant +emphasis-50-15+    1)
   (defconstant +emphasis-reserved+ 2)
  
positive.code:                               (+ (* 72  (/ bit-rate sample-rate)) padded)))))))
  
  (defmethod load-frame ((me frame) &key instream (read-payload nil))
    "Load an MPEG frame from current file position"
    (fastest
      (log5:with-context "load-frame"
        (handler-case
  
negative.code: 
  (define-condition mpeg-bad-header (mpeg-condition) ())
  
  (defconstant +sync-word+  #x7ff "NB: this is 11 bits so as to be able to recognize V2.5")
  
  ;;; the versions
  (defconstant +mpeg-2.5+   0)
  (defconstant +v-reserved+ 1)
  (defconstant +mpeg-2+     2)
  