--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/mmlibs/mmfw/Recogniser/src/matparser.cpp Thu Oct 07 22:34:12 2010 +0100
@@ -0,0 +1,352 @@
+// Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of "Eclipse Public License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.eclipse.org/legal/epl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+//
+
+#include "constants.h"
+#include "parsers.h"
+
+//
+// Matroska 'XML' tags.
+//
+static const TUint32 KEBML = 0x1A45DFA3;
+static const TUint32 KSegment = 0x18538067;
+static const TUint32 KTracks = 0x1654AE6B;
+static const TUint32 KTrackEntry = 0xAE;
+static const TUint32 KTrackType = 0x83;
+static const TUint32 KVoid = 0xEC;
+static const TUint32 KSeekHead = 0x114D9B74;
+static const TUint32 KSegmentInfo = 0x1549A966;
+static const TUint32 KCluster = 0x1F43B675;
+static const TUint32 KCues = 0x1C53BB6B;
+static const TUint32 KAttachments = 0x1941A469;
+static const TUint32 KChapters = 0x1043A770;
+static const TUint32 KTags = 0x1254C367;
+
+//
+// Matroska Track Types.
+//
+static const TUint8 KTrackTypeVideo = 0x01;
+
+#define KMatroskaConfidenceMask 0x07 // 00000111
+#define KMatroskaEBMLBit KBit1
+#define KMatroskaSegmentBit KBit2
+#define KMatroskaVideoBit KBit3
+
+
+//
+// This truth table maps the following flags to confidence levels.
+//
+// A: Extension match.
+// B: EBML tag found.
+// C: Segment tag found.
+//
+// C B A -> Confidence
+// --------------------
+// 0 0 0 -> NotRecognised
+// 0 0 1 -> EPossible
+// 0 1 0 -> EPossible
+// 0 1 1 -> EProbable
+// 1 0 0 -> ENotRecognised (EBML should be present)
+// 1 0 1 -> ENotRecognised (EBML should be present)
+// 1 1 0 -> EProbable
+// 1 1 1 -> ECertain
+//
+static const TInt KMatroskaFlagsToConfidence[8] =
+ {
+ KConfNotRecognised,
+ KConfPossible,
+ KConfPossible,
+ KConfProbable,
+ KConfNotRecognised,
+ KConfNotRecognised,
+ KConfProbable,
+ KConfCertain
+ };
+
+static const TInt KMatExtensionOnlyIndex = 1; // See truth table.
+
+
+typedef struct
+ {
+ const TText* iExt;
+ const TText8* iMime;
+ }
+TMatroskaExt;
+
+//
+// Known Matroska extensions and their corresponding MIME-types.
+//
+static const TMatroskaExt KMatroskaExt[] =
+ {
+ {KExtMAT_A, KMimeMAT_A },
+ {KExtMAT_V, KMimeMAT_V }
+ };
+
+static const TInt KMatroskaExtCount = sizeof(KMatroskaExt) / sizeof(TMatroskaExt);
+
+
+//
+//
+//
+TMatroskaParser::TMatroskaParser(CReader& aReader, TFlags& aFlags)
+ : iReader(aReader),
+ iFlags(aFlags)
+ {
+ }
+
+
+//
+//
+//
+const TText8* TMatroskaParser::MatchExtension(const TDesC& aExt)
+ {
+ for (TInt i = 0; i < KMatroskaExtCount; i++)
+ {
+ if (aExt.MatchF(TPtrC(KMatroskaExt[i].iExt)) != KErrNotFound)
+ {
+ return KMatroskaExt[i].iMime;
+ }
+ }
+
+ return NULL;
+ }
+
+
+//
+// This function calls the parser and turns the results
+// into a MIME-type.
+//
+void TMatroskaParser::DoRecognise(const TDesC& aExt, CReader& aReader, TMatch& aMatch)
+ {
+ TFlags flags;
+ TMatroskaParser parser(aReader, flags);
+
+ // Try to match the extension.
+ const TText8* extMime = parser.MatchExtension(aExt);
+ if (extMime != NULL)
+ {
+ flags.SetExtensionFlag();
+ }
+
+ // Try to parse the content.
+ TRAP_IGNORE(parser.ParseL());
+ TInt confIndex = flags.GetBitField(KMatroskaConfidenceMask);
+ aMatch.iConfidence = KMatroskaFlagsToConfidence[confIndex];
+ if (aMatch.iConfidence != KConfNotRecognised)
+ {
+ // If any header data has been recognised trust that,
+ // otherwise go with the extension.
+ if (confIndex == KMatExtensionOnlyIndex)
+ {
+ aMatch.iMime = extMime;
+ }
+ else
+ {
+ aMatch.iMime = (flags.GetBitField(KMatroskaVideoBit) ? KMimeMAT_V : KMimeMAT_A);
+ }
+ }
+ }
+
+
+//
+// This function does the parsing.
+//
+void TMatroskaParser::ParseL()
+ {
+ TUint64 id;
+ TInt64 size;
+ TBool haveElement = EFalse;
+
+ // Assume there's video content if we only have buffer data.
+ if (iReader.Type() == CReader::EBuffer)
+ {
+ iFlags.SetBit(KMatroskaVideoBit);
+ }
+
+ FOREVER
+ {
+ if (!haveElement)
+ {
+ ReadElementL(id, size);
+ }
+
+ switch (id)
+ {
+ case KEBML:
+ iFlags.SetBit(KMatroskaEBMLBit);
+ break;
+
+ case KSegment:
+ haveElement = ReadSegmentL(id, size);
+ break;
+
+ default:
+ // Skip it.
+ iReader.SeekL(size);
+ }
+ }
+ }
+
+
+//
+// This function returns ETrue if the aNextID and aNextSize parameters
+// contain valid values, EFalse otherwise.
+//
+TBool TMatroskaParser::ReadSegmentL(TUint64& aNextID, TInt64& aNextSize)
+ {
+ TUint64 id;
+ TInt64 size;
+ TBool videoContent = EFalse;
+
+ aNextID = 0;
+ aNextSize = 0;
+
+ iFlags.SetBit(KMatroskaSegmentBit);
+
+ while (!videoContent)
+ {
+ ReadElementL(id, size);
+
+ switch (id)
+ {
+ case KTracks:
+ videoContent = ReadTrackL(size);
+ break;
+
+ case KSeekHead:
+ case KSegmentInfo:
+ case KCluster:
+ case KCues:
+ case KAttachments:
+ case KChapters:
+ case KTags:
+ iReader.SeekL(size);
+ break;
+
+ default:
+ // Unrecognised element id. Pass it back to the caller
+ aNextID = id;
+ aNextSize = size;
+ return ETrue;
+ }
+ }
+
+ // Tell the caller they must read the next element themselves.
+ return EFalse;
+ }
+
+
+//
+// The Track. This lets us know if there's video content present.
+//
+TBool TMatroskaParser::ReadTrackL(TInt64 aTrackSize)
+ {
+ TUint64 id;
+ TInt64 size;
+ TInt startPos = iReader.Position();
+
+ while (iReader.Position() - startPos < aTrackSize)
+ {
+ ReadElementL(id, size);
+
+ switch (id)
+ {
+ case KTrackEntry:
+ break;
+
+ case KTrackType:
+ TUint8 trackType;
+ iReader.ReadByteL(trackType);
+ if (trackType == KTrackTypeVideo)
+ {
+ // We found video content so we can stop parsing.
+ iFlags.SetBit(KMatroskaVideoBit);
+ return ETrue;
+ }
+ break;
+
+ default:
+ iReader.SeekL(size);
+ }
+ }
+
+ return EFalse;
+ }
+
+
+//
+//
+//
+void TMatroskaParser::ReadElementL(TUint64& aElementID, TInt64& aSize)
+ {
+ do
+ {
+ aElementID = ReadDataL();
+ aSize = ReadDataL(ETrue);
+
+ // Void elements are used for padding and
+ // can be ignored.
+ if (aElementID == KVoid)
+ {
+ iReader.SeekL(aSize);
+ }
+ }
+ while (aElementID == KVoid);
+ }
+
+
+//
+//
+//
+TUint64 TMatroskaParser::ReadDataL(TBool aTurnOffHighestSetBit)
+ {
+ TUint64 retval;
+ TUint8 byte;
+ TUint8 mask = 0x80; // [1000 0000]. It will be shifted right 1 in each 'i' iteration.
+ TUint8 size = 1; // It will be incremented in each 'i' iteration.
+
+ iReader.ReadByteL(byte);
+
+ for (TInt i = 0; i < sizeof(TUint64); i++)
+ {
+ if (byte & mask)
+ {
+ retval = byte;
+ if (aTurnOffHighestSetBit)
+ {
+ retval &= ~mask; // Turn off the highest set bit.
+ }
+
+ // Now read the real data.
+ // Start from 1 because we've already read a byte.
+ for (TInt j = 1; j < size; j++)
+ {
+ iReader.ReadByteL(byte);
+ retval <<= 8;
+ retval |= byte;
+ }
+
+ return retval;
+ }
+ else
+ {
+ mask >>= 1;
+ size++;
+ }
+ }
+
+ User::Leave(KErrCorrupt);
+ return 0; // Keep the compiler happy.
+ }
+