Fixed detecting frame borders in MPEG-2 streams that have "bottom fields" or varying GOP structures

CONTRIBUTORS

@@ -620,6 +620,8 @@ Helmut Auer <vdr@helmutauer.de>
  command line option to be left empty to use the default values if only ENC shall be set
  for reporting an inconsistent behavior between opening the Recordings menu manually
  via the main menu and by pressing the Recordings key
+ for helping to debug a problem with frame detection in MPEG-2 streams that have "bottom fields"
+ or varying GOP structures
 
 Jeremy Hall <jhall@UU.NET>
  for fixing an incomplete initialization of the filter parameters in eit.c
@@ -3192,3 +3194,7 @@ Eike Edener <eike@edener.de>
 Eike Sauer <EikeSauer@t-online.de>
  for reporting a problem with channels that need more than 5 TS packets for detecting
  frame borders
+
+Christian Paulick <cpaulick@xeatre.tv>
+ for reporting a problem with frame detection in MPEG-2 streams that have "bottom fields"
+ or varying GOP structures

HISTORY

@@ -7878,4 +7878,6 @@ Video Disk Recorder Revision History
 - Increased MIN_TS_PACKETS_FOR_FRAME_DETECTOR to 10 in order to be able to record
   channels that need more than 5 TS packets for detecting frame borders (reported by
   Eike Sauer).
+- Fixed detecting frame borders in MPEG-2 streams that have "bottom fields" or varying
+  GOP structures (reported by Christian Paulick, with help from Helmut Auer).
 - Fixed a wrong alignment in cCiDateTime::SendDateTime().

remux.c

@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: remux.c 2.75 2013/03/03 10:37:58 kls Exp $
+ * $Id: remux.c 2.75.1.1 2014/01/25 14:37:05 kls Exp $
  */
 
 #include "remux.h"
@@ -1004,6 +1004,7 @@ protected:
   bool debug;
   bool newFrame;
   bool independentFrame;
+  int iFrameTemporalReferenceOffset;
 public:
   cFrameParser(void);
   virtual ~cFrameParser() {};
@@ -1017,6 +1018,7 @@ public:
   void SetDebug(bool Debug) { debug = Debug; }
   bool NewFrame(void) { return newFrame; }
   bool IndependentFrame(void) { return independentFrame; }
+  int IFrameTemporalReferenceOffset(void) { return iFrameTemporalReferenceOffset; }
   };
 
 cFrameParser::cFrameParser(void)
@@ -1024,6 +1026,7 @@ cFrameParser::cFrameParser(void)
   debug = true;
   newFrame = false;
   independentFrame = false;
+  iFrameTemporalReferenceOffset = 0;
 }
 
 // --- cAudioParser ----------------------------------------------------------
@@ -1056,6 +1059,7 @@ class cMpeg2Parser : public cFrameParser {
 private:
   uint32_t scanner;
   bool seenIndependentFrame;
+  int lastIFrameTemporalReference;
 public:
   cMpeg2Parser(void);
   virtual int Parse(const uchar *Data, int Length, int Pid);
@@ -1065,6 +1069,7 @@ cMpeg2Parser::cMpeg2Parser(void)
 {
   scanner = EMPTY_SCANNER;
   seenIndependentFrame = false;
+  lastIFrameTemporalReference = -1; // invalid
 }
 
 int cMpeg2Parser::Parse(const uchar *Data, int Length, int Pid)
@@ -1089,10 +1094,25 @@ int cMpeg2Parser::Parse(const uchar *Data, int Length, int Pid)
             scanner = OldScanner;
             return tsPayload.Used() - TS_SIZE;
             }
+         uchar b1 = tsPayload.GetByte();
+         uchar b2 = tsPayload.GetByte();
+         int TemporalReference = (b1 << 2 ) + ((b2 & 0xC0) >> 6);
+         uchar FrameType = (b2 >> 3) & 0x07;
+         if (tsPayload.Find(0x000001B5)) { // Extension start code
+            if (((tsPayload.GetByte() & 0xF0) >> 4) == 0x08) { // Picture coding extension
+               tsPayload.GetByte();
+               uchar PictureStructure = tsPayload.GetByte() & 0x03;
+               if (PictureStructure == 0x02) // bottom field
+                  break;
+               }
+            }
          newFrame = true;
-         tsPayload.GetByte();
-         uchar FrameType = (tsPayload.GetByte() >> 3) & 0x07;
          independentFrame = FrameType == 1; // I-Frame
+         if (independentFrame) {
+            if (lastIFrameTemporalReference >= 0)
+               iFrameTemporalReferenceOffset = TemporalReference - lastIFrameTemporalReference;
+            lastIFrameTemporalReference = TemporalReference;
+            }
          if (debug) {
             seenIndependentFrame |= independentFrame;
             if (seenIndependentFrame) {
@@ -1457,7 +1477,7 @@ int cFrameDetector::Analyze(const uchar *Data, int Length)
                        for (int i = 0; i < numPtsValues; i++)
                            ptsValues[i] = ptsValues[i + 1] - ptsValues[i];
                        qsort(ptsValues, numPtsValues, sizeof(uint32_t), CmpUint32);
-                       uint32_t Delta = ptsValues[0] / framesPerPayloadUnit;
+                       uint32_t Delta = ptsValues[0] / (framesPerPayloadUnit +  parser->IFrameTemporalReferenceOffset());
                        // determine frame info:
                        if (isVideo) {
                           if (abs(Delta - 3600) <= 1)
@@ -1475,7 +1495,7 @@ int cFrameDetector::Analyze(const uchar *Data, int Length)
                           }
                        else // audio
                           framesPerSecond = double(PTSTICKS) / Delta; // PTS of audio frames is always increasing
-                       dbgframes("\nDelta = %d  FPS = %5.2f  FPPU = %d NF = %d\n", Delta, framesPerSecond, framesPerPayloadUnit, numPtsValues + 1);
+                       dbgframes("\nDelta = %d  FPS = %5.2f  FPPU = %d NF = %d TRO = %d\n", Delta, framesPerSecond, framesPerPayloadUnit, numPtsValues + 1, parser->IFrameTemporalReferenceOffset());
                        synced = true;
                        parser->SetDebug(false);
                        }