Playback Subtitle fixes

Fix these problems
- External text subtitles displayed at the same time as internal subtitles.
- Selecting external subtitles from the menu not displaying any subtitles.
- Intermittent segmentation faults when enabling subtitles.
- External subtitles not appearing when switching from internal to external.

External text subtitles now being processed by FFmpeg are treated
as AV subtitles but still need to be identified as external text
subtitles.

- Add a flag to identify external subtitles to SubtitleReader.
- When internal subtitles are selected, discard external subtitles
- When external subtitles are selected, discard internal subtitles.
- Add checks to prevent segmentation faults on invalid frames.
- Set needsync. When switching from AV subtitles to external
  subtitles the subtitles were not showing.

Refs #773

mythtv/libs/libmythtv/captions/subtitlereader.cpp

@@ -57,7 +57,8 @@ void SubtitleReader::SeekFrame(int64_t ts, int flags)
 
 bool SubtitleReader::AddAVSubtitle(AVSubtitle &subtitle,
                                    bool fix_position,
-                                   bool allow_forced)
+                                   bool allow_forced,
+                                   bool  isExternal)
 {
     bool enableforced = false;
     bool forced = false;
@@ -66,7 +67,7 @@ bool SubtitleReader::AddAVSubtitle(AVSubtitle &subtitle,
         forced = forced || static_cast<bool>(subtitle.rects[i]->flags & AV_SUBTITLE_FLAG_FORCED);
     }
 
-    if (!m_avSubtitlesEnabled)
+    if (!m_avSubtitlesEnabled && !isExternal)
     {
         if (!forced)
         {
@@ -87,6 +88,19 @@ bool SubtitleReader::AddAVSubtitle(AVSubtitle &subtitle,
         enableforced = true;
     }
 
+    if (m_textSubtitlesEnabled && !isExternal || m_avSubtitlesEnabled && isExternal)
+    {
+        FreeAVSubtitle(subtitle);
+        return enableforced;
+    }
+
+    // Sanity check to prevent seg fault
+    if (subtitle.num_rects > 1000)
+    {
+        FreeAVSubtitle(subtitle);
+        return enableforced;
+    }
+
 #ifdef DEBUG_SUBTITLES
     if (VERBOSE_LEVEL_CHECK(VB_PLAYBACK, LOG_DEBUG))
     {

mythtv/libs/libmythtv/captions/subtitlereader.h

@@ -56,7 +56,7 @@ class SubtitleReader : public QObject
 
     AVSubtitles* GetAVSubtitles(void) { return &m_avSubtitles; }
     bool AddAVSubtitle(AVSubtitle& subtitle, bool fix_position,
-                       bool allow_forced);
+                       bool allow_forced, bool isExternal);
     void ClearAVSubtitles(void);
     static void FreeAVSubtitle(AVSubtitle &sub);
 

mythtv/libs/libmythtv/captions/subtitlescreen.cpp

@@ -1846,7 +1846,9 @@ void SubtitleScreen::DisplayAVSubtitles(void)
 
     AVSubtitles* subs = m_subreader->GetAVSubtitles();
     QMutexLocker lock(&(subs->m_lock));
-    if (subs->m_buffers.empty() && (kDisplayAVSubtitle != m_subtitleType))
+    if (subs->m_buffers.empty()
+      && (kDisplayAVSubtitle != m_subtitleType)
+      && (kDisplayTextSubtitle != m_subtitleType))
         return;
 
     MythVideoOutput *videoOut = m_player->GetVideoOutput();
@@ -1898,7 +1900,11 @@ void SubtitleScreen::DisplayAVSubtitles(void)
 #endif
             }
             lock.relock();
+            subs->m_needSync = false;
 
+            // extra check to avoid segfault
+            if (subs->m_buffers.empty())
+                return;
             AVSubtitle subtitle = subs->m_buffers.front();
             if (subtitle.end_display_time < currentFrame->m_timecode.count())
             {
@@ -2060,7 +2066,6 @@ void SubtitleScreen::DisplayAVSubtitles(void)
 #ifdef USING_LIBASS
     RenderAssTrack(currentFrame->m_timecode, assForceNext);
 #endif
-    subs->m_needSync = false;
 }
 
 int SubtitleScreen::DisplayScaledAVSubtitles(const AVSubtitleRect *rect,

mythtv/libs/libmythtv/captions/textsubtitleparser.cpp

@@ -255,7 +255,7 @@ int TextSubtitleParser::ReadNextSubtitle(void)
     sub.start_display_time = av_q2d(m_stream->time_base) * m_pkt->dts * 1000;
     sub.end_display_time = av_q2d(m_stream->time_base) * (m_pkt->dts + m_pkt->duration) * 1000;
 
-    m_parent->AddAVSubtitle(sub, m_decCtx->codec_id == AV_CODEC_ID_XSUB, false);
+    m_parent->AddAVSubtitle(sub, m_decCtx->codec_id == AV_CODEC_ID_XSUB, false, true);
     return ret;
 }
 
@@ -275,8 +275,8 @@ void TextSubtitleParser::LoadSubtitles(bool inBackground)
     }
 
     // External subtitles are now presented as AV Subtitles.
-    m_parent->EnableAVSubtitles(true);
-    m_parent->EnableTextSubtitles(false);
+    m_parent->EnableAVSubtitles(false);
+    m_parent->EnableTextSubtitles(true);
     m_parent->EnableRawTextSubtitles(false);
 
     local_buffer_t sub_data {};

mythtv/libs/libmythtv/decoders/avformatdecoder.cpp

@@ -3969,7 +3969,7 @@ bool AvFormatDecoder::ProcessSubtitlePacket(AVStream *curstream, AVPacket *pkt)
 
         bool forcedon = m_parent->GetSubReader(pkt->stream_index)->AddAVSubtitle(
                 subtitle, curstream->codecpar->codec_id == AV_CODEC_ID_XSUB,
-                m_parent->GetAllowForcedSubtitles());
+                m_parent->GetAllowForcedSubtitles(), false);
          m_parent->EnableForcedSubtitles(forcedon || isForcedTrack);
     }
 

mythtv/libs/libmythtv/mythplayercaptionsui.cpp

@@ -216,6 +216,8 @@ void MythPlayerCaptionsUI::EnableCaptions(uint Mode, bool UpdateOSD)
     if (kDisplayTextSubtitle & Mode)
     {
         m_captionsOverlay.EnableSubtitles(kDisplayTextSubtitle);
+        AVSubtitles* subs = m_subReader.GetAVSubtitles();
+        subs->m_needSync = true;
         msg += tr("Text subtitles");
     }
 
@@ -423,7 +425,7 @@ bool MythPlayerCaptionsUI::HasCaptionTrack(uint Mode)
     if (Mode == kDisplayNUVTeletextCaptions)
         return true;
     // External subtitles are now decoded with FFmpeg and are AVSubtitles.
-    if ((Mode == kDisplayAVSubtitle) && m_captionsState.m_externalTextSubs)
+    if ((Mode == kDisplayAVSubtitle || Mode == kDisplayTextSubtitle) && m_captionsState.m_externalTextSubs)
         return true;
     if (!(Mode == kDisplayTextSubtitle) && m_decoder->GetTrackCount(toTrackType(Mode)))
         return true;