From: Mike Brady <mikebrady@eircom.net>
Date: Sun, 10 Dec 2017 22:26:19 +0000 (+0000)
Subject: Improve the sync between AirPlay and movies like YouTube. Not sure we understand... 
X-Git-Tag: 3.1.5~3^2~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=86f76ad6ce9291ebd95321c1b40f023c2e822fad;p=thirdparty%2Fshairport-sync.git

Improve the sync between AirPlay and movies like YouTube. Not sure we understand the negotiation for syncing.
---

diff --git a/player.h b/player.h
index 6ee4f4d0..3c9f43d0 100644
--- a/player.h
+++ b/player.h
@@ -63,7 +63,7 @@ typedef struct {
 
 typedef struct {
   int connection_number; // for debug ID purposes, nothing else...
-
+  int64_t staticLatencyCorrection; // it seems iTunes needs some offset before it's more or less right. Odd.
 #if defined(HAVE_DBUS) || defined(HAVE_MPRIS)
   enum session_status_type play_state;
 #endif
diff --git a/rtp.c b/rtp.c
index 1e082bd1..22646d79 100644
--- a/rtp.c
+++ b/rtp.c
@@ -227,10 +227,10 @@ void *rtp_control_receiver(void *arg) {
         sync_rtp_timestamp = monotonic_timestamp(ntohl(*((uint32_t *)&packet[16])), conn);
 
         if (config.use_negotiated_latencies) {
-          int64_t la = sync_rtp_timestamp - rtp_timestamp_less_latency + 11025;
+          int64_t la = sync_rtp_timestamp - rtp_timestamp_less_latency + conn->staticLatencyCorrection;
           if (la != config.latency) {
             config.latency = la;
-            // debug(1,"Using negotiated latency of %u frames.",config.latency);
+            debug(1,"Using negotiated latency of %lld frames and a static latency correction of %lld",sync_rtp_timestamp - rtp_timestamp_less_latency,conn->staticLatencyCorrection);
           }
         }
 
diff --git a/rtsp.c b/rtsp.c
index d32bc266..41a5a85f 100644
--- a/rtsp.c
+++ b/rtsp.c
@@ -765,11 +765,12 @@ static void handle_setup(rtsp_conn_info *conn, rtsp_message *req, rtsp_message *
       else
         debug(2, "iTunes Version Number not found.");
       if (iTunesVersion >= 10) {
-        debug(2, "User-Agent is iTunes 10 or better, (actual version is %d); "
+        debug(1, "User-Agent is iTunes 10 or better, (actual version is %d); "
                  "selecting the iTunes "
                  "latency of %d frames.",
               iTunesVersion, config.iTunesLatency);
         config.latency = config.iTunesLatency;
+        conn->staticLatencyCorrection = 11025;
       }
     } else if (strstr(ua, "AirPlay") == ua) {
       debug(2, "User-Agent is AirPlay; selecting the AirPlay latency of %d frames.",
@@ -780,6 +781,7 @@ static void handle_setup(rtsp_conn_info *conn, rtsp_message *req, rtsp_message *
                "of %d frames.",
             config.ForkedDaapdLatency);
       config.latency = config.ForkedDaapdLatency;
+      conn->staticLatencyCorrection = 11025;
     } else {
       debug(2, "Unrecognised User-Agent. Using latency of %d frames.", config.latency);
     }