without first checking to make sure it's available.
Clear the Info column as soon as we've accepted a packet.
In the "MPEG" dissector, if no subdissector accepts the packet, dissect
it as just "MPEG" data.
svn path=/trunk/; revision=21187
checking to make sure it's available.
Don't dissect an audio frame if it doesn't have a valid version or layer
value.
Don't do anything with the columns until we've decided to accept a
frame.
The register routines are only called once; we don't have to check
whether they've already been called.
svn path=/trunk/; revision=21186
