public void Parse(IH264Reader reader, IResultNodeState resultState)
{
long bytesRemaining = (reader.Length - reader.Position);
if (bytesRemaining < 4)
{
resultState.Invalidate();
return;
}
long startPosition = reader.Position;
// Check whether a sequence parameter set and a picture parameter set are
// separated by exactly one byte in a NAL unit stream.
// This is the case for H.264 streams embedded in 3GPP files.
ulong nextFiveBytes = reader.PeekFiveBytes();
if ((_state.NalUnitType == NalUnitType.SequenceParameterSet) &&
!IsShortLengthPrefixedNalUnit((uint)(nextFiveBytes >> 16), bytesRemaining) &&
IsShortLengthPrefixedNalUnit((uint)(nextFiveBytes >> 8) & 0xffffff, (bytesRemaining - 1)))
{
// Skip the byte that is part of the 3GPP container
reader.Position++;
bytesRemaining--;
nextFiveBytes = reader.PeekFiveBytes();
}
if (IsShortLengthPrefixedNalUnit((uint)(nextFiveBytes >> 16), bytesRemaining))
{
if (ParseShortLengthPrefixedNalUnit(reader, resultState) && resultState.Valid)
{
return; // Successfully parse SPS or PPS NAL unit
}
resultState.Reset();
reader.Position = startPosition;
}
if (IsLongLengthPrefixedNalUnit(nextFiveBytes, bytesRemaining))
{
if (ParseLongLengthPrefixedNalUnit(reader, resultState))
{
return; // Successfully parse slice NAL unit
}
}
resultState.Invalidate();
}
public bool TryDefaultHeaders(IResultNodeState resultState, Action evaluateHeader)
{
if (!IsDetectingReferenceHeader() || !resultState.Valid)
{
return(false);
}
// This will make sure the reference headers are tested no more than twice (and not for every slice)
_state.ReferenceHeadersTestCount++;
long startPosition = Position;
// Try reference headers to decode this slice
foreach (var referenceHeader in ReferenceHeaders)
{
// Ignore reference headers with 'byte stream' <-> 'NAL unit stream' format mismatch
if (referenceHeader.Value.SequenceState.ByteStreamFormat == _state.ByteStreamFormat)
{
referenceHeader.Value.CopyTo(_state);
evaluateHeader();
// The restult state should be valid *AND* the slice should actually have been decoded!!!!
if (resultState.Valid && (_state.SliceState != null))
{
_state.ReferenceHeader = referenceHeader.Key;
return(true); // Header successfully decoded!
}
}
_state.SequenceStates.Clear();
_state.PictureStates.Clear();
resultState.Reset();
Position = startPosition;
}
// Not able to decode slice using any reference header, defaulting to unparsable slices
return(false);
}