Fix uninitialized scalar values

Fixes CID #1086903
Ensure extradata is available before freeing it.

Fixes CID #1086897
Don't run the audio deinterleaving for real audio on a flush.

Fixes CID #1086895
Remove unused variables

Fixes CID #1041218, #1041217
Initialize variable in constructor

Fixes CID ##1041212
Initialize alpha value to 0

Fixes CID #1041174
Move demuxer init down to where its needed.

This avoids a resource leak in an error case.
Fixes CID #1041164
Free memory on failure

Fixes CID #1041160
De-allocate the memory buffer when the registry value could not be read.

Fixes CID #1041155
Initialize class members

Fixes CID #1041204, #1041212, #1041203, #966280