Support negative latencies.

CHANGELOG.md

@@ -6,17 +6,24 @@ This change log follows the conventions of
 
 ## [Unreleased][unreleased]
 
-Updated to incorporate much newer versions of underlying libraries,
-including Beat Link, which adds support for six players when used with
-a DJM-V10, and high-precision tracking of playback position for the
-CDJ-3000, including movements and looping inside of individual beats.
+### Changed
+
+- Allow negative latencies thanks to user reports of beat packets
+  arriving before beats are heard.
+
+- Updated to incorporate much newer versions of underlying libraries,
+  including Beat Link, which adds support for six players when used
+  with a DJM-V10, and high-precision tracking of playback position for
+  the CDJ-3000, including movements and looping inside of individual
+  beats.
 
 ## [0.1.1] - 2020-12-28
 
 ### Changed
 
 - Updated `beat-Link` and `beat-carabiner` libraries to incorporate
   fixes and new features as well as Ableton Link 3.0.3.
+
 - Added type hints for the Clojure compiler to avoid reflection and
   improve runtime performance.
 

src/open_beat_control/core.clj

@@ -83,7 +83,7 @@
    ["-l" "--latency MS" "How many milliseconds are we behind the CDJs"
     :default 20
     :parse-fn #(Long/parseLong %)
-    :validate [#(<= 0 % 500) "Must be a number between 0 and 500 inclusive"]]
+    :validate [#(<= -1000 % 1000) "Must be a number between -1000 and 1000"]]
    ["-L" "--log-file PATH" "Log to a rotated file instead of stdout"
     :validate [valid-log-file? @log-file-error]]
    ["-h" "--help" "Display help information and exit"]])