Merge pull request sannies#85 from aldenml/encryption-box-fix

Fixed write of entries count in AbstractSampleEncryptionBox. 
(your input file must be a bit broken - but this fixed doesn't hurt at all - thx)

isoparser/src/main/java/com/googlecode/mp4parser/boxes/AbstractSampleEncryptionBox.java

@@ -121,7 +121,7 @@ protected void getContent(ByteBuffer byteBuffer) {
  IsoTypeWriter.writeUInt8(byteBuffer, ivSize);
  byteBuffer.put(kid);
  }
- IsoTypeWriter.writeUInt32(byteBuffer, entries.size());
+ IsoTypeWriter.writeUInt32(byteBuffer, getNonEmptyEntriesNum());
  for (CencSampleAuxiliaryDataFormat entry : entries) {
  if (entry.getSize() > 0) {
  if (entry.iv.length != 8 && entry.iv.length != 16) {
@@ -139,6 +139,17 @@ protected void getContent(ByteBuffer byteBuffer) {
  }
  }
 
+ private int getNonEmptyEntriesNum() {
+ int n = 0;
+ for (CencSampleAuxiliaryDataFormat entry : entries) {
+ if (entry.getSize() > 0) {
+ n++;
+ }
+ }
+
+ return n;
+ }
+
  @Override
  protected long getContentSize() {
  long contentSize = 4;