dvdplayer: improve audio sync for large packet durations

1 files changed, 26 insertions, 2 deletions

diff --git a/xbmc/cores/dvdplayer/DVDPlayerAudio.cpp b/xbmc/cores/dvdplayer/DVDPlayerAudio.cpp
index 2f83d655b5..8b96e05139 100644
--- a/xbmc/cores/dvdplayer/DVDPlayerAudio.cpp
+++ b/xbmc/cores/dvdplayer/DVDPlayerAudio.cpp
@@ -757,8 +757,24 @@ bool CDVDPlayerAudio::OutputPacket(DVDAudioFrame &audioframe)
     double clock = m_pClock->GetClock(absolute);
     double error = m_dvdAudio.GetPlayingPts() - clock;
     m_dvdAudio.SetResampleRatio(1.0);
-    if (error > 0)
+
+    // sync audio by skipping or dropping frames if we are above or
+    // below a given threshold. the constants are aligned with known
+    // durations: DTS = 11ms, AC3 = 32ms
+    // during this stage audio is muted
+    if (error > DVD_MSEC_TO_TIME(10))
     {
+      unsigned int nb_frames = audioframe.nb_frames;
+      double duration = audioframe.duration;
+
+      // reduce large packets for better sync, i.e. FLAC can have 96ms packets
+      // 32ms because I know this works good for AC3
+      if (audioframe.duration > DVD_MSEC_TO_TIME(32) && audioframe.sample_rate)
+      {
+        audioframe.nb_frames = 0.032 * audioframe.sample_rate;
+        audioframe.duration = ((double)audioframe.nb_frames * DVD_TIME_BASE) / audioframe.sample_rate;
+      }
+
       int dups = std::min(DVD_MSEC_TO_TIME(100), error) / audioframe.duration;
       if (dups > 0)
         CLog::Log(LOGNOTICE,"CDVDPlayerAudio::OutputPacket duplicate %d packets of duration %d",
@@ -767,14 +783,22 @@ bool CDVDPlayerAudio::OutputPacket(DVDAudioFrame &audioframe)
       {
         m_dvdAudio.AddPackets(audioframe);
       }
+
+      audioframe.nb_frames = nb_frames;
+      audioframe.duration = duration;
+
       m_dvdAudio.AddPackets(audioframe);
     }
-    else
+    else if (error < -DVD_MSEC_TO_TIME(32))
     {
       m_dvdAudio.SetPlayingPts(audioframe.pts);
       CLog::Log(LOGNOTICE,"CDVDPlayerAudio::OutputPacket skipping a packets of duration %d",
                 DVD_TIME_TO_MSEC(audioframe.duration));
     }
+    else
+    {
+      m_dvdAudio.AddPackets(audioframe);
+    }
   }
   else if (m_synctype == SYNC_DISCON)
   {