public MetadataDictionary ReadMetadata(Stream stream)
{
Contract.Ensures(Contract.Result <MetadataDictionary>() != null);
var buffer = new byte[4096];
using (var decoder = new NativeVorbisDecoder())
{
NativeOggStream oggStream = null;
var vorbisComment = new VorbisComment();
try
{
SafeNativeMethods.VorbisCommentInitialize(out vorbisComment);
using (var sync = new NativeOggSync())
{
OggPage page;
do
{
// Read from the buffer into a page:
while (sync.PageOut(out page) != 1)
{
int bytesRead = stream.Read(buffer, 0, buffer.Length);
if (bytesRead == 0)
{
throw new IOException(Resources.ReadError);
}
IntPtr nativeBuffer = sync.Buffer(bytesRead);
Marshal.Copy(buffer, 0, nativeBuffer, bytesRead);
sync.Wrote(bytesRead);
}
if (oggStream == null)
{
oggStream = new NativeOggStream(SafeNativeMethods.OggPageGetSerialNumber(ref page));
}
oggStream.PageIn(ref page);
OggPacket packet;
while (oggStream.PacketOut(out packet) == 1)
{
decoder.HeaderIn(ref vorbisComment, ref packet);
if (packet.PacketNumber == 1)
{
return(new VorbisCommentToMetadataAdapter(vorbisComment));
}
}
} while (SafeNativeMethods.OggPageEndOfStream(ref page) == 0);
throw new IOException(Resources.EndOfStreamError);
}
}
finally
{
oggStream?.Dispose();
SafeNativeMethods.VorbisCommentClear(ref vorbisComment);
}
}
}
