SVN Update# 4991 by tong2shot: mp4parser:
- use ByteBuffer instead of MappedByteBuffer in FileDataSourceImpl, it fixes "Out of memory" error and deletion bugs in Windows OS.
- add support for AAC track within FLV container (FlvAacTrackImpl).
- add support for building iTunes compatible m4a.

YouTube:
- add support for audio extraction (mp3 or m4a).
- prefer dash audio for audio conversion for the same audio bitrate.