Playback: AvSync2 fix fast forward/rewind

Fast forward and rewind were not handling frame timing correctly so that
they were dropping frames, resulting in no frames displayed in some cases.

(cherry picked from commit 4089bf1)

mythtv/libs/libmythtv/mythplayer.cpp

@@ -2212,6 +2212,12 @@ void MythPlayer::AVSync2(VideoFrame *buffer)
 
         now = QDateTime::currentDateTimeUtc();
         unow = now.toMSecsSinceEpoch() * 1000;
+
+        if (!normal_speed || FlagIsSet(kMusicChoice))
+        {
+            framedue = unow + frame_interval;
+            break;
+        }
         // first time or after a seek - setup of rtcbase
         if (rtcbase == 0)
         {
@@ -2249,10 +2255,10 @@ void MythPlayer::AVSync2(VideoFrame *buffer)
         lateness = unow - framedue;
         dropframe = false;
         if (lateness > 30000)
-            dropframe = !FlagIsSet(kMusicChoice) && numdroppedframes < 10;
+            dropframe = numdroppedframes < 10;
 
         if (lateness <= 30000 && prior_audiotimecode > 0
-            && prior_videotimecode > 0 && normal_speed && !FlagIsSet(kMusicChoice))
+            && prior_videotimecode > 0)
         {
             // Get video in sync with audio
             audio_adjustment = prior_audiotimecode - prior_videotimecode;
@@ -2279,8 +2285,7 @@ void MythPlayer::AVSync2(VideoFrame *buffer)
                 pause_audio = true;
         }
         // sanity check - reset rtcbase if time codes have gone crazy.
-        if ((lateness > AVSYNC_MAX_LATE || lateness < - AVSYNC_MAX_LATE)
-            && !FlagIsSet(kMusicChoice))
+        if ((lateness > AVSYNC_MAX_LATE || lateness < - AVSYNC_MAX_LATE))
         {
             framedue = 0;
             rtcbase = 0;