anchor.diff:  					(make-array (suggested-buffer-size rec) :element-type '(unsigned-byte 8)))))
     (setf (cdr (last (chunk-queue rec))) (chunk-queue rec)
   	(rcursor rec) (chunk-queue rec)
  -	(wcursor rec) (chunk-queue rec)))
  +	(wcursor rec) (cdr (chunk-queue rec))))
   
   (defclass video-stream ()
     ((filename :accessor filename :initarg :filename :initform nil)))
  
positive.code:       (jpeg:decode-stream is :buffer (frame chunk)
  			  :descriptor (jpeg-descriptor rec)))
      (bt:release-lock cur-lock)))
  
  (defmethod pop-chunk ((rec stream-record))
    (bt:with-lock-held ((vacancy-lock (car (rcursor rec))))
      (prog1 (car (rcursor rec))
        (pop (rcursor rec)))))
  
  (defmethod initialize-instance :after ((s avi-mjpeg-stream) &key &allow-other-keys)
    (setf (chunk-decoder s) #'(lambda (stream id size)
  
negative.code:    (chunk-queue :accessor chunk-queue)
     (rcursor :accessor rcursor)
     (wcursor :accessor wcursor)
     (final :accessor final :initform nil)
     (avi :accessor avi :initarg :avi)))
  
  (defmethod stream-playback-start ((rec stream-record))
    (bt:acquire-lock (vacancy-lock (car (rcursor rec)))))
  
  (defmethod stream-playback-stop ((rec stream-record))
    (bt:release-lock (vacancy-lock (car (rcursor rec)))))
  
  (defclass mjpeg-stream-record (stream-record)
    ((buffer :accessor buffer :type '(unsigned-byte 8))
  