internal bool DescendToAtom([NotNull, ItemNotNull] params string[] hierarchy)
{
Reset();
using (var reader = new Mp4Reader(_stream))
{
foreach (var fourCc in hierarchy)
{
do
{
var subAtom = new AtomInfo((uint)_stream.Position, reader.ReadUInt32BigEndian(),
reader.ReadFourCc());
if (subAtom.End > _stream.Length)
{
throw new EndOfStreamException($"{fourCc} atom is missing.");
}
if (fourCc.Equals(subAtom.FourCc, StringComparison.Ordinal))
{
_atomInfoStack.Push(subAtom);
_stream.Seek(GetDataLength(fourCc), SeekOrigin.Current);
break;
}
_stream.Position = subAtom.End;
} while (_stream.Position < (_atomInfoStack.Count == 0 ? _stream.Length : _atomInfoStack.Peek().End));
}
}
return(hierarchy.Last().Equals(_atomInfoStack.Peek().FourCc, StringComparison.Ordinal));
}
internal AtomInfo[] GetChildAtomInfo()
{
var result = new List <AtomInfo>();
using (var reader = new Mp4Reader(_stream))
{
_stream.Position = _atomInfoStack.Count == 0
? 0
: _atomInfoStack.Peek().Start + 8 + GetDataLength(_atomInfoStack.Peek().FourCc);
while (_stream.Position < (_atomInfoStack.Count == 0 ? _stream.Length : _atomInfoStack.Peek().End))
{
var childAtom = new AtomInfo(
(uint)_stream.Position,
reader.ReadUInt32BigEndian(),
reader.ReadFourCc());
// The stream might be padded with empty space
if (childAtom.FourCc.Equals("\0\0\0\0", StringComparison.Ordinal))
{
_stream.Position = result.Count > 0 ? result.Last().End : 0;
break;
}
result.Add(childAtom);
_stream.Position = childAtom.End;
}
}
return(result.ToArray());
}
internal byte[] ReadAtom([NotNull] AtomInfo atom)
{
_stream.Position = atom.Start;
using (var reader = new Mp4Reader(_stream))
return(reader.ReadBytes((int)atom.Size));
}
internal void UpdateStco(uint offset)
{
DescendToAtom("moov", "trak", "mdia", "minf", "stbl", "stco");
_stream.Seek(4, SeekOrigin.Current);
using (var reader = new Mp4Reader(_stream))
using (var writer = new Mp4Writer(_stream))
{
var count = reader.ReadUInt32BigEndian();
var dataStart = _stream.Position;
for (var i = 0; i < count; i++)
{
_stream.Position = dataStart + i * 4;
var value = reader.ReadUInt32BigEndian();
_stream.Seek(-4, SeekOrigin.Current);
writer.WriteBigEndian(value + offset);
}
}
}
