/// <summary>
/// Saves the changes made in the current instance to the
/// file it represents.
/// </summary>
public override void Save()
{
if (udta_boxes.Count == 0)
{
IsoUserDataBox udtaBox = new IsoUserDataBox();
udta_boxes.Add(udtaBox);
}
// Try to get into write mode.
Mode = File.AccessMode.Write;
try
{
FileParser parser = new FileParser(this);
parser.ParseBoxHeaders();
InvariantStartPosition = parser.MdatStartPosition;
InvariantEndPosition = parser.MdatEndPosition;
long size_change = 0;
long write_position = 0;
// To avoid rewriting udta blocks which might not have been modified,
// the code here will work correctly if:
// 1. There is a single udta for the entire file
// - OR -
// 2. There are multiple utdtas, but only 1 of them contains the Apple ILST box.
// We should be OK in the vast majority of cases
IsoUserDataBox udtaBox = FindAppleTagUdta();
if (null == udtaBox)
{
udtaBox = new IsoUserDataBox();
}
ByteVector tag_data = udtaBox.Render();
// If we don't have a "udta" box to overwrite...
if (udtaBox.ParentTree == null ||
udtaBox.ParentTree.Length == 0)
{
// Stick the box at the end of the moov box.
BoxHeader moov_header = parser.MoovTree[
parser.MoovTree.Length - 1];
size_change = tag_data.Count;
write_position = moov_header.Position +
moov_header.TotalBoxSize;
Insert(tag_data, write_position, 0);
// Overwrite the parent box sizes.
for (int i = parser.MoovTree.Length - 1; i >= 0;
i--)
{
size_change = parser.MoovTree[i
].Overwrite(this, size_change);
}
}
else
{
// Overwrite the old box.
BoxHeader udta_header = udtaBox.ParentTree[udtaBox.ParentTree.Length - 1];
size_change = tag_data.Count -
udta_header.TotalBoxSize;
write_position = udta_header.Position;
Insert(tag_data, write_position,
udta_header.TotalBoxSize);
// Overwrite the parent box sizes.
for (int i = udtaBox.ParentTree.Length - 2; i >= 0;
i--)
{
size_change = udtaBox.ParentTree[i
].Overwrite(this, size_change);
}
}
// If we've had a size change, we may need to adjust
// chunk offsets.
if (size_change != 0)
{
// We may have moved the offset boxes, so we
// need to reread.
parser.ParseChunkOffsets();
InvariantStartPosition = parser.MdatStartPosition;
InvariantEndPosition = parser.MdatEndPosition;
foreach (Box box in parser.ChunkOffsetBoxes)
{
IsoChunkLargeOffsetBox co64 =
box as IsoChunkLargeOffsetBox;
if (co64 != null)
{
co64.Overwrite(this,
size_change,
write_position);
continue;
}
IsoChunkOffsetBox stco =
box as IsoChunkOffsetBox;
if (stco != null)
{
stco.Overwrite(this,
size_change,
write_position);
continue;
}
}
}
TagTypesOnDisk = TagTypes;
}
finally
{
Mode = File.AccessMode.Closed;
}
}
