[demuxers/Matroska] Try to extract missing AV1 extradata from a keyframe

This should fix the inability to save some Matroska files with AV1 video
track as Matroska in copy mode.

avidemux_plugins/ADM_demuxers/Matroska/ADM_mkv.h

@@ -69,6 +69,7 @@ class mkvTrak
         _defaultFrameDuration=0;
         language=ADM_UNKNOWN_LANGUAGE;
         _needBuffering=0;
+        _needExtraData=0;
         _secondField=false;
         _nalSize=-1;
   }
@@ -97,6 +98,7 @@ class mkvTrak
   uint32_t  _defaultFrameDuration; // Duration of ONE frame in us!
   std::string language;
   int       _needBuffering;
+  int       _needExtraData; // Positive and no extradata: try to extract. Negative: give up.
   bool      _secondField; // Used to clear keyframe flag from the second field
   uint32_t  _nalSize; // Used to decode frame type in H.264 and HEVC streams
 };

avidemux_plugins/ADM_demuxers/Matroska/ADM_mkvEntries.cpp

@@ -246,6 +246,8 @@ uint8_t mkvHeader::analyzeOneTrack(void *head,uint32_t headlen)
         {
             _tracks[0].extraData=entry.extraData;
             _tracks[0].extraDataLen=entry.extraDataLen;
+            if(fourCC::check(entry.fcc,(uint8_t *)"av01") && !entry.extraDataLen)
+                _tracks[0]._needExtraData = 1; // try to extract it from the first keyframe during indexing
         }
         if(isH264Compatible(entry.fcc) && _tracks[0].extraData
             && _tracks[0].extraDataLen > 8 // FIXME

avidemux_plugins/ADM_demuxers/Matroska/ADM_mkvIndexer.cpp

@@ -201,10 +201,28 @@ uint8_t mkvHeader::addIndexEntry(uint32_t track,ADM_ebml_file *parser,uint64_t w
         delete [] readBuffer;
         readBufferSize=size*2;
         readBuffer=new uint8_t[readBufferSize];
+        memset(readBuffer,0,readBufferSize);
     }
     if(!track)
     {
         aprintf("adding image at 0x%llx , time = %d\n",where,timecodeMS);
+        if(Track->_needExtraData > 0 && (flags & AVI_KEY_FRAME))
+        {
+            if(rpt)
+                memcpy(readBuffer,_tracks[0].headerRepeat,rpt);
+            parser->readBin(readBuffer+rpt,size-3);
+            uint8_t *dest = NULL;
+            int l = ADM_extractVideoExtraData(_videostream.fccHandler, size, readBuffer, &dest);
+            if(l < 0)
+            {
+                Track->_needExtraData = l;
+            }else if(l > 0)
+            {
+                Track->extraData = dest;
+                Track->extraDataLen = l;
+                Track->_needExtraData = 0;
+            }
+        }
     }
     // since frame type is unreliable for mkv, we scan each frame
     // For the 2 most common cases : mp4 & h264.
@@ -609,6 +627,7 @@ uint8_t mkvHeader::indexClusters(ADM_ebml_file *parser)
 
     readBufferSize = 200*1024;
     readBuffer = new uint8_t[readBufferSize];
+    memset(readBuffer,0,readBufferSize);
 
     // Search segment
     fileSize=parser->getFileSize();