public BitCodec<CramRecord> buildCodec(
CramHeader header, CompressionHeader compression,
SequenceBaseProvider referenceBaseProvider,
DefaultMutableTreeNode root) throws CramException {
CramRecordCodec recordCodec = new CramRecordCodec();
if (root == null)
root = buildNode(recordCodec, "Cram record codec");
recordCodec.prevPosInSeq = compression.firstRecordPosition;