public static IEnumerable <eBoxType> readChildren(this Mp4Reader reader)
{
int lvl = reader.level;
Debug.Assert(lvl > 0);
Debug.Assert(reader.currentBox.isContainer());
lvl--;
while (true)
{
eBoxType boxType = reader.readBox();
// Console.WriteLine( "{0}: {1}", reader.currentBoxNames, boxType );
if (boxType == eBoxType.ChildContainerEnd)
{
if (reader.level == lvl)
{
yield break;
}
}
else
{
yield return(boxType);
}
}
}
public static string print(this eBoxType box)
{
if (Enum.IsDefined(typeof(eBoxType), box))
{
return(box.ToString());
}
byte[] bytes = BitConverter.GetBytes((uint)box);
return($"\"{ Encoding.ASCII.GetString( bytes ) }\"");
}
public eBoxType readBox()
{
dbgVerifyOffset();
if (stack.Count > 0 && !stack.Peek().type.isContainer())
{
skipCurrentBox();
}
if (stack.Count > 0)
{
Debug.Assert(stack.Peek().type.isContainer());
if (!skipToNextBox())
{
return(eBoxType.ChildContainerEnd);
}
}
long startOffset = currentOffset;
Span <byte> first8bytes = stackalloc byte[8];
if (!tryReadBytes(first8bytes))
{
return(eBoxType.Empty);
}
ReadOnlySpan <uint> header = first8bytes.cast <uint>();
// Damn byte order. Pretty much all big endian platforms died decades ago, yet we still suffer from that BS in 2020.
uint size = BinaryPrimitives.ReverseEndianness(header[0]);
eBoxType bt = (eBoxType)header[1];
if (size == 0)
{
throw new NotImplementedException("Boxes without size are valid according to the spec, but not currently supported by this library.");
}
if (size != 1)
{
currentBoxEnd = startOffset + size;
}
else
{
// 64-bit size version
Span <byte> sizeExt = stackalloc byte[8];
readBytes(sizeExt);
ulong val = sizeExt.cast <ulong>()[0];
val = BinaryPrimitives.ReverseEndianness(val);
currentBoxEnd = startOffset + (long)val;
}
stack.Push(new sCurrentBox(bt, currentBoxEnd));
return(bt);
}
public static void moveToBox(this Mp4Reader reader, eBoxType boxType)
{
while (true)
{
var bt = reader.readBox();
if (bt == boxType)
{
return;
}
if (bt == eBoxType.Empty)
{
throw new EndOfStreamException();
}
}
}
public sCurrentBox(eBoxType type, long endOffset)
{
this.type = type;
this.endOffset = endOffset;
}
public static bool isContainer(this eBoxType box)
{
return(containerBoxes.Contains(box));
}
