Boolean MatroskaFileParser::parseEBMLVal_unsigned(EBMLDataSize& size, unsigned& result) {
if (size.val() > 4) return False; // size too large
u_int64_t result64;
if (!parseEBMLVal_unsigned64(size, result64)) return False;
result = (unsigned)result64;
return True;
}
Boolean MatroskaFileParser::parseEBMLVal_float(EBMLDataSize& size, float& result) {
switch (size.val()) {
case 4: {
unsigned resultAsUnsigned;
if (!parseEBMLVal_unsigned(size, resultAsUnsigned)) return False;
result = *(float*)&resultAsUnsigned;
return True;
}
case 8: {
u_int64_t resultAsU64;
if (!parseEBMLVal_unsigned64(size, resultAsU64)) return False;
result = (float)*(double*)&resultAsU64;
return True;
}
default: {
return False;
}
}
}
Boolean MatroskaFileParser::parseCues() {
#if defined(DEBUG) || defined(DEBUG_CUES)
fprintf(stderr, "parsing Cues\n");
#endif
EBMLId id;
EBMLDataSize size;
// Read the next header, which should be MATROSKA_ID_CUES:
if (!parseEBMLIdAndSize(id, size) || id != MATROSKA_ID_CUES) return True; // The header wasn't what we expected, so we're done
fLimitOffsetInFile = fCurOffsetInFile + size.val(); // Make sure we don't read past the end of this header
double currentCueTime = 0.0;
u_int64_t currentClusterOffsetInFile = 0;
while (fCurOffsetInFile < fLimitOffsetInFile) {
while (!parseEBMLIdAndSize(id, size)) {}
#ifdef DEBUG_CUES
if (id == MATROSKA_ID_CUE_POINT) fprintf(stderr, "\n"); // makes debugging output easier to read
fprintf(stderr, "MatroskaFileParser::parseCues(): Parsed id 0x%s (%s), size: %lld\n", id.hexString(), id.stringName(), size.val());
#endif
switch (id.val()) {
case MATROSKA_ID_CUE_POINT: { // 'Cue Point' header: enter this
break;
}
case MATROSKA_ID_CUE_TIME: { // 'Cue Time' header: get this value
unsigned cueTime;
if (parseEBMLVal_unsigned(size, cueTime)) {
currentCueTime = cueTime*(fOurFile.fTimecodeScale/1000000000.0);
#ifdef DEBUG_CUES
fprintf(stderr, "\tCue Time %d (== %f seconds)\n", cueTime, currentCueTime);
#endif
}
break;
}
case MATROSKA_ID_CUE_TRACK_POSITIONS: { // 'Cue Track Positions' header: enter this
break;
}
case MATROSKA_ID_CUE_TRACK: { // 'Cue Track' header: get this value (but only for debugging; we don't do anything with it)
unsigned cueTrack;
if (parseEBMLVal_unsigned(size, cueTrack)) {
#ifdef DEBUG_CUES
fprintf(stderr, "\tCue Track %d\n", cueTrack);
#endif
}
break;
}
case MATROSKA_ID_CUE_CLUSTER_POSITION: { // 'Cue Cluster Position' header: get this value
u_int64_t cueClusterPosition;
if (parseEBMLVal_unsigned64(size, cueClusterPosition)) {
currentClusterOffsetInFile = fOurFile.fSegmentDataOffset + cueClusterPosition;
#ifdef DEBUG_CUES
fprintf(stderr, "\tCue Cluster Position %llu (=> offset within the file: %llu (0x%llx))\n", cueClusterPosition, currentClusterOffsetInFile, currentClusterOffsetInFile);
#endif
// Record this cue point:
fOurFile.addCuePoint(currentCueTime, currentClusterOffsetInFile, 1/*default block number within cluster*/);
}
break;
}
case MATROSKA_ID_CUE_BLOCK_NUMBER: { // 'Cue Block Number' header: get this value
unsigned cueBlockNumber;
if (parseEBMLVal_unsigned(size, cueBlockNumber) && cueBlockNumber != 0) {
#ifdef DEBUG_CUES
fprintf(stderr, "\tCue Block Number %d\n", cueBlockNumber);
#endif
// Record this cue point (overwriting any existing entry for this cue time):
fOurFile.addCuePoint(currentCueTime, currentClusterOffsetInFile, cueBlockNumber);
}
break;
}
default: { // We don't process this header, so just skip over it:
skipHeader(size);
#ifdef DEBUG_CUES
fprintf(stderr, "\tskipped %lld bytes\n", size.val());
#endif
break;
}
}
setParseState();
}
fLimitOffsetInFile = 0; // reset
#if defined(DEBUG) || defined(DEBUG_CUES)
fprintf(stderr, "done parsing Cues\n");
#endif
#ifdef DEBUG_CUES
fprintf(stderr, "Cue Point tree: ");
fOurFile.printCuePoints(stderr);
fprintf(stderr, "\n");
#endif
return True; // we're done parsing Cues
}
void MatroskaFileParser::lookForNextTrack() {
#ifdef DEBUG
fprintf(stderr, "looking for Track\n");
#endif
EBMLId id;
EBMLDataSize size;
// Read and skip over (or enter) each Matroska header, until we get to a 'Track'.
while (fCurrentParseState == LOOKING_FOR_TRACKS) {
while (!parseEBMLIdAndSize(id, size)) {}
#ifdef DEBUG
fprintf(stderr, "MatroskaFileParser::lookForNextTrack(): Parsed id 0x%s (%s), size: %lld\n", id.hexString(), id.stringName(), size.val());
#endif
switch (id.val()) {
case MATROSKA_ID_SEGMENT: { // 'Segment' header: enter this
// Remember the position, within the file, of the start of Segment data, because Seek Positions are relative to this:
fOurFile.fSegmentDataOffset = fCurOffsetInFile;
break;
}
case MATROSKA_ID_SEEK_HEAD: { // 'Seek Head' header: enter this
break;
}
case MATROSKA_ID_SEEK: { // 'Seek' header: enter this
break;
}
case MATROSKA_ID_SEEK_ID: { // 'Seek ID' header: get this value
if (parseEBMLNumber(fLastSeekId)) {
#ifdef DEBUG
fprintf(stderr, "\tSeek ID 0x%s:\t%s\n", fLastSeekId.hexString(), fLastSeekId.stringName());
#endif
}
break;
}
case MATROSKA_ID_SEEK_POSITION: { // 'Seek Position' header: get this value
u_int64_t seekPosition;
if (parseEBMLVal_unsigned64(size, seekPosition)) {
u_int64_t offsetInFile = fOurFile.fSegmentDataOffset + seekPosition;
#ifdef DEBUG
fprintf(stderr, "\tSeek Position %llu (=> offset within the file: %llu (0x%llx))\n", seekPosition, offsetInFile, offsetInFile);
#endif
// The only 'Seek Position's that we care about are for 'Cluster' and 'Cues':
if (fLastSeekId == MATROSKA_ID_CLUSTER) {
fOurFile.fClusterOffset = offsetInFile;
} else if (fLastSeekId == MATROSKA_ID_CUES) {
fOurFile.fCuesOffset = offsetInFile;
}
}
break;
}
case MATROSKA_ID_INFO: { // 'Segment Info' header: enter this
break;
}
case MATROSKA_ID_TIMECODE_SCALE: { // 'Timecode Scale' header: get this value
unsigned timecodeScale;
if (parseEBMLVal_unsigned(size, timecodeScale) && timecodeScale > 0) {
fOurFile.fTimecodeScale = timecodeScale;
#ifdef DEBUG
fprintf(stderr, "\tTimecode Scale %u ns (=> Segment Duration == %f seconds)\n", fOurFile.timecodeScale(), fOurFile.fileDuration());
#endif
}
break;
}
case MATROSKA_ID_DURATION: { // 'Segment Duration' header: get this value
if (parseEBMLVal_float(size, fOurFile.fSegmentDuration)) {
#ifdef DEBUG
fprintf(stderr, "\tSegment Duration %f (== %f seconds)\n", fOurFile.segmentDuration(), fOurFile.fileDuration());
#endif
}
break;
}
case MATROSKA_ID_TRACKS: { // enter this, and move on to parsing 'Tracks'
fLimitOffsetInFile = fCurOffsetInFile + size.val(); // Make sure we don't read past the end of this header
fCurrentParseState = PARSING_TRACK;
break;
}
default: { // skip over this header
skipHeader(size);
#ifdef DEBUG
fprintf(stderr, "\tskipped %lld bytes\n", size.val());
#endif
break;
}
}
setParseState();
}
}