avformatdecoder: improve fps detection in normalized_fps()

This should fix issues with mov style containers by using the avg_frame_rate
which is set by the demuxer.

NOTE: Using estimated_fps seems to always be accurate for everything except
matroska and mov. It appears that ffmpeg takes into account the codec and
container fps when generating estimated_fps. Also, XBMC uses
estimated_fps for everything except matroska. We should probably do the same.

Fixes #10300.
(cherry picked from commit 6c22eda)

Author: tralph

mythtv/libs/libmythtv/avformatdecoder.cpp

@@ -1079,50 +1079,53 @@ int AvFormatDecoder::OpenFile(RingBuffer *rbuffer, bool novideo,
 
 float AvFormatDecoder::normalized_fps(AVStream *stream, AVCodecContext *enc)
 {
-    float fps, avg_fps, stream_fps, container_fps, estimated_fps;
-    avg_fps = stream_fps = container_fps = estimated_fps = 0.0f;
+    float fps, avg_fps, codec_fps, container_fps, estimated_fps;
+    avg_fps = codec_fps = container_fps = estimated_fps = 0.0f;
 
     if (stream->avg_frame_rate.den && stream->avg_frame_rate.num)
         avg_fps = av_q2d(stream->avg_frame_rate); // MKV default_duration
 
     if (enc->time_base.den && enc->time_base.num) // tbc
-        stream_fps = 1.0f / av_q2d(enc->time_base) / enc->ticks_per_frame;
+        codec_fps = 1.0f / av_q2d(enc->time_base) / enc->ticks_per_frame;
     // Some formats report fps waaay too high. (wrong time_base)
-    if (stream_fps > 121.0f && (enc->time_base.den > 10000) &&
+    if (codec_fps > 121.0f && (enc->time_base.den > 10000) &&
         (enc->time_base.num == 1))
     {
         enc->time_base.num = 1001;  // seems pretty standard
         if (av_q2d(enc->time_base) > 0)
-            stream_fps = 1.0f / av_q2d(enc->time_base);
+            codec_fps = 1.0f / av_q2d(enc->time_base);
     }
     if (stream->time_base.den && stream->time_base.num) // tbn
         container_fps = 1.0f / av_q2d(stream->time_base);
     if (stream->r_frame_rate.den && stream->r_frame_rate.num) // tbr
         estimated_fps = av_q2d(stream->r_frame_rate);
 
-    if (QString(ic->iformat->name).contains("matroska") && 
+    // matroska demuxer sets the default_duration to avg_frame_rate
+    // mov,mp4,m4a,3gp,3g2,mj2 demuxer sets avg_frame_rate
+    if ((QString(ic->iformat->name).contains("matroska") ||
+        QString(ic->iformat->name).contains("mov")) &&
         avg_fps < 121.0f && avg_fps > 3.0f)
-        fps = avg_fps; // matroska default_duration
-    else if (QString(ic->iformat->name).contains("avi") && 
+        fps = avg_fps;
+    else if (QString(ic->iformat->name).contains("avi") &&
         container_fps < 121.0f && container_fps > 3.0f)
         fps = container_fps; // avi uses container fps for timestamps
-    else if (stream_fps < 121.0f && stream_fps > 3.0f) 
-        fps = stream_fps;
-    else if (container_fps < 121.0f && container_fps > 3.0f) 
+    else if (codec_fps < 121.0f && codec_fps > 3.0f)
+        fps = codec_fps;
+    else if (container_fps < 121.0f && container_fps > 3.0f)
         fps = container_fps;
-    else if (estimated_fps < 70.0f && estimated_fps > 20.0f) 
+    else if (estimated_fps < 121.0f && estimated_fps > 3.0f)
         fps = estimated_fps;
+    else if (avg_fps < 121.0f && avg_fps > 3.0f)
+        fps = avg_fps;
     else
-        fps = stream_fps;
+        fps = 30000.0f / 1001.0f; // 29.97 fps
 
-    // If it is still out of range, just assume NTSC...
-    fps = (fps > 121.0f) ? (30000.0f / 1001.0f) : fps;
     if (fps != m_fps)
     {
         VERBOSE(VB_PLAYBACK, LOC +
-                QString("Selected FPS is %1 (avg %2 stream %3 "
+                QString("Selected FPS is %1 (avg %2 codec %3 "
                         "container %4 estimated %5)").arg(fps).arg(avg_fps)
-                        .arg(stream_fps).arg(container_fps).arg(estimated_fps));
+                        .arg(codec_fps).arg(container_fps).arg(estimated_fps));
         m_fps = fps;
     }