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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,179 @@ | ||
| (ns beat-carabiner.carabiner | ||
| "Maintains the connection with the local Carabiner daemon to | ||
| participate in an Ableton Link session. Based on the version in | ||
| beat-link-trigger, but simpler because it has no need to be | ||
| asynchronous, nor to support graceful shutdown, because as a | ||
| single-purpose daemon ourselves, we will run until terminated." | ||
| (:require [taoensso.timbre :as timbre]) | ||
| (:import [java.net Socket InetSocketAddress])) | ||
|
|
||
| (defonce ^{:private true | ||
| :doc "When connected, holds the socket that can be used to | ||
| send messages to Carabiner, the configured latency value, and values | ||
| which track the peer count and tempo reported by the Ableton Link | ||
| session and the target tempo we are trying to maintain (when | ||
| applicable)."} | ||
| client (atom {})) | ||
|
|
||
| (def bpm-tolerance | ||
| "The amount by which the Link tempo can differ from our target tempo | ||
| without triggering an adjustment." | ||
| 0.00001) | ||
|
|
||
| (def skew-tolerance | ||
| "The amount by which the start of a beat can be off without | ||
| triggering an adjustment. This can't be larger than the normal beat | ||
| packet jitter without causing spurious readjustments." | ||
| 0.0166) | ||
|
|
||
| (def connect-timeout | ||
| "How long the connection attempt to the Carabiner daemon can take | ||
| before we give up on being able to reach it." | ||
| 5000) | ||
|
|
||
| (defn- send-message | ||
| "Sends a message to the active Carabiner daemon, if we are | ||
| connected." | ||
| ([message] | ||
| (when-let [socket (:socket @client)] | ||
| (send-message socket message))) | ||
| ([socket message] | ||
| (.write (.getOutputStream socket) (.getBytes (str message) "UTF-8")))) | ||
|
|
||
| (defn- check-tempo | ||
| "If we are supposed to lock the Link tempo, make sure the Link | ||
| tempo is close enough to our target value, and adjust it if needed." | ||
| [] | ||
| (let [state @client] | ||
| (when (and (some? (:target-bpm state)) | ||
| (> (Math/abs (- (:link-bpm state 0.0) (:target-bpm state))) bpm-tolerance)) | ||
| (send-message (str "bpm " (:target-bpm state)))))) | ||
|
|
||
| (defn- handle-status | ||
| "Processes a status update from Carabiner." | ||
| [status] | ||
| (let [bpm (double (:bpm status)) | ||
| peers (int (:peers status))] | ||
| (swap! client assoc :link-bpm bpm :link-peers peers)) | ||
| (check-tempo)) | ||
|
|
||
| (defn- handle-beat-at-time | ||
| "Processes a beat probe response from Carabiner." | ||
| [socket info] | ||
| (let [raw-beat (Math/round (:beat info)) | ||
| beat-skew (mod (:beat info) 1.0) | ||
| [time beat-number] (:beat @client) | ||
| candidate-beat (if (and beat-number (= time (:when info))) | ||
| (let [bar-skew (- (dec beat-number) (mod raw-beat 4)) | ||
| adjustment (if (<= bar-skew -2) (+ bar-skew 4) bar-skew)] | ||
| (+ raw-beat adjustment)) | ||
| raw-beat) | ||
| target-beat (if (neg? candidate-beat) (+ candidate-beat 4) candidate-beat)] | ||
| (when (or (> (Math/abs beat-skew) skew-tolerance) | ||
| (not= target-beat raw-beat)) | ||
| (timbre/info "Realigning Ableton Link to beat" target-beat "by" beat-skew) | ||
| (send-message socket (str "force-beat-at-time " target-beat " " (:when info) " 4.0"))))) | ||
|
|
||
| (defn- response-handler | ||
| "A loop that reads messages from Carabiner as long as it has a | ||
| connection, and takes appropriate action." | ||
| [socket] | ||
| (timbre/info "Connected to Carabiner.") | ||
| (try | ||
| (let [buffer (byte-array 1024) | ||
| input (.getInputStream socket)] | ||
| (while (not (.isClosed socket)) | ||
| (try | ||
| (let [n (.read input buffer)] | ||
| (if (pos? n) ; We got data | ||
| (let [message (String. buffer 0 n "UTF-8") | ||
| reader (java.io.PushbackReader. (clojure.java.io/reader (.getBytes message "UTF-8"))) | ||
| cmd (clojure.edn/read reader)] | ||
| (timbre/debug "Received:" message) | ||
| (case cmd | ||
| status (handle-status (clojure.edn/read reader)) | ||
| beat-at-time (handle-beat-at-time socket (clojure.edn/read reader)) | ||
| (timbre/error "Unrecognized message from Carabiner:" message))) | ||
| (do ; We read zero, means the other side closed; force our loop to terminate. | ||
| (timbre/warn "Carabiner unexpectedly closed our connection; is it still running?") | ||
| (.close socket)))) | ||
| (catch java.net.SocketTimeoutException e | ||
| (timbre/info "Read from Carabiner timed out, did not expect this to happen.")) | ||
| (catch Exception e | ||
| (timbre/error e "Problem reading from Carabiner."))))) | ||
| (catch Exception e | ||
| (timbre/error e "Problem managing Carabiner read loop.")) | ||
| (finally | ||
| (.close socket) ; In case we got here through an exception | ||
| (swap! client dissoc :socket :link-bpm :link-peers) | ||
| (timbre/info "Ending read loop from Carabiner.")))) | ||
|
|
||
| (defn connect | ||
| "Try to establish a connection to Carabiner, and run a loop to | ||
| process any responses from it. Will return only upon failure, or if | ||
| the connection has closed. Sets up a background thread to reject the | ||
| connection if we have not received an initial status report from the | ||
| Carabiner daemon within a second of opening it." | ||
| [port latency] | ||
| (try | ||
| (let [socket (Socket.)] | ||
| (try | ||
| (.connect socket (InetSocketAddress. "127.0.0.1" port) connect-timeout) | ||
| (swap! client assoc :socket socket :latency latency) | ||
| (future | ||
| (Thread/sleep 1000) | ||
| (when-not (:link-bpm @client) | ||
| (timbre/warn "Did not receive inital status packet from Carabiner daemon; disconnecting.") | ||
| (.close socket))) | ||
| (catch Exception e | ||
| (timbre/warn e "Unable to connect to Carabiner."))) | ||
| (when (.isConnected socket) (response-handler socket))) | ||
| (catch Exception e | ||
| (timbre/warn e "Problem running Carabiner response handler loop.")))) | ||
|
|
||
| (defn valid-tempo? | ||
| "Checks whether a tempo request is a reasonable number of beats per | ||
| minute. Link supports the range 20 to 999 BPM. If you want something | ||
| outside that range, pick the closest multiple or fraction; for | ||
| example for 15 BPM, propose 30 BPM." | ||
| [bpm] | ||
| (< 20.0 bpm 999.0)) | ||
|
|
||
| (defn- validate-tempo | ||
| "Makes sure a tempo request is a reasonable number of beats per | ||
| minute. Coerces it to a double value if it is in the legal Link | ||
| range, otherwise throws an exception." | ||
| [bpm] | ||
| (if (valid-tempo? bpm) | ||
| (double bpm) | ||
| (throw (IllegalArgumentException. "Tempo must be between 20 and 999 BPM")))) | ||
|
|
||
| (defn lock-tempo | ||
| "Starts holding the tempo of the Link session to the specified | ||
| number of beats per minute." | ||
| [bpm] | ||
| (timbre/info "Locking Ableton Link tempo to" bpm) | ||
| (swap! client assoc :target-bpm (validate-tempo bpm)) | ||
| (check-tempo)) | ||
|
|
||
| (defn unlock-tempo | ||
| "Allow the tempo of the Link session to be controlled by other | ||
| participants." | ||
| [] | ||
| (timbre/info "Unlocking Ableton Link tempo.") | ||
| (swap! client dissoc :target-bpm)) | ||
|
|
||
| (defn beat-at-time | ||
| "Find out what beat falls at the specified time in the Link | ||
| timeline, assuming 4 beats per bar since we are dealing with Pro DJ | ||
| Link, and taking into account the configured latency. When the | ||
| response comes, nudge the Link timeline so that it had a beat at the | ||
| same time. If a beat-number (ranging from 1 to the quantum) is | ||
| supplied, move the timeline by more than a beat if necessary in | ||
| order to get the Link session's bars aligned as well." | ||
| ([time] | ||
| (beat-at-time time nil)) | ||
| ([time beat-number] | ||
| (let [adjusted-time (- time (* (:latency @client) 1000))] | ||
| (swap! client assoc :beat [adjusted-time beat-number]) | ||
| (send-message (str "beat-at-time " adjusted-time " 4.0"))))) |
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