skip any audio before first vpts for smoother play start

From: Mark Spieth <mspieth@digivation.com.au>


---
 mythtv/libs/libmythtv/avformatdecoder.cpp |   23 +++++++++++++++++++++++
 mythtv/libs/libmythtv/avformatdecoder.h   |    2 ++
 2 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/mythtv/libs/libmythtv/avformatdecoder.cpp b/mythtv/libs/libmythtv/avformatdecoder.cpp
index ae4a017..676c999 100644
--- a/mythtv/libs/libmythtv/avformatdecoder.cpp
+++ b/mythtv/libs/libmythtv/avformatdecoder.cpp
@@ -262,6 +262,7 @@ AvFormatDecoder::AvFormatDecoder(MythPlayer *parent,
       start_code_state(0xffffffff),
       lastvpts(0),                  lastapts(0),
       lastccptsu(0),
+      firstvpts(0),                 firstvptsinuse(false),
       faulty_pts(0),                faulty_dts(0),
       last_pts_for_fault_detection(0),
       last_dts_for_fault_detection(0),
@@ -716,6 +717,12 @@ void AvFormatDecoder::SeekReset(long long newKey, uint skipFrames,
         if (decoded_video_frame)
             m_parent->DiscardVideoFrame(decoded_video_frame);
     }
+
+    if (doflush)
+    {
+        firstvpts = 0;
+        firstvptsinuse = true;
+    }
 }
 
 void AvFormatDecoder::Reset(bool reset_video_data, bool seek_reset)
@@ -2765,7 +2772,9 @@ void AvFormatDecoder::MpegPreProcessPkt(AVStream *stream, AVPacket *pkt)
 
                 gopset = false;
                 prevgoppos = 0;
+                firstvpts =
                 lastapts = lastvpts = lastccptsu = 0;
+                firstvptsinuse = true;
                 faulty_pts = faulty_dts = 0;
                 last_pts_for_fault_detection = 0;
                 last_dts_for_fault_detection = 0;
@@ -2871,7 +2880,9 @@ bool AvFormatDecoder::H264PreProcessPkt(AVStream *stream, AVPacket *pkt)
 
             gopset = false;
             prevgoppos = 0;
+            firstvpts =
             lastapts = lastvpts = lastccptsu = 0;
+            firstvptsinuse = true;
             faulty_pts = faulty_dts = 0;
             last_pts_for_fault_detection = 0;
             last_dts_for_fault_detection = 0;
@@ -3141,6 +3152,8 @@ bool AvFormatDecoder::ProcessVideoPacket(AVStream *curstream, AVPacket *pkt)
     framesPlayed++;
 
     lastvpts = temppts;
+    if (!firstvpts && firstvptsinuse)
+        firstvpts = temppts;
 
     return true;
 }
@@ -4020,6 +4033,16 @@ bool AvFormatDecoder::ProcessAudioPacket(AVStream *curstream, AVPacket *pkt,
                 skipaudio = false;
         }
 
+        // skip any audio frames preceding first video frame
+        if (firstvptsinuse && firstvpts && (lastapts < firstvpts))
+        {
+            VERBOSE(VB_PLAYBACK+VB_TIMESTAMP,
+                LOC + QString("discarding early audio timecode %1 %2 %3")
+                .arg(pkt->pts).arg(pkt->dts).arg(lastapts));
+            break;
+        }
+        firstvptsinuse = false;
+
         avcodeclock->lock();
         data_size = 0;
 
diff --git a/mythtv/libs/libmythtv/avformatdecoder.h b/mythtv/libs/libmythtv/avformatdecoder.h
index d3947e5..55ae68a 100644
--- a/mythtv/libs/libmythtv/avformatdecoder.h
+++ b/mythtv/libs/libmythtv/avformatdecoder.h
@@ -276,6 +276,8 @@ class AvFormatDecoder : public DecoderBase
     long long lastvpts;
     long long lastapts;
     long long lastccptsu;
+    long long firstvpts;
+    bool      firstvptsinuse;
 
     int64_t faulty_pts;
     int64_t faulty_dts;