Licenses GPL and LGPL

Hello,

I am new to Cortado and I am very interested in playing video in some of my Java applets using the Theora decoder. I would like to write a LGPL library to use the decoders in Processing (see processing.org).

I prefer LGPL over GPL because it allows a wider usage of the library. The core libraries of Processing are released under LGPL as well.

I would like to use com.fluendo.plugin and com.fluendo.jheora which are LGPL, but the problem is that they use some classes from com.fluendo.jst and com.fluendo.utils that have a GPL license at the beginning of the file. I think that if you need a single GPL file to compile a LGPL library, the whole must be released under the GPL (and cannot be released under the LGPL), am I right? 

It is weird because half the files in the jst package are GPL and the other half are LGPL. Maybe the license changed at some point and some of the files haven't been modified. Could someone confirm the current license of these files? (according to the Copyright should be Fluendo S.L.) 

The GPL files that I am concerned about are: 

com.fluendo.jst
 Buffer
 Bus
 Clock
 ClockProvider
 Event
 Format
 Message
 Query
 SystemClock

com.fluendo.utils
 Base64Converter
 Debug
 MemUtils

com.fluendo.jst is used by com.fluendo.plugin
com.fluendo.utils is used everywhere (plugin, jtheora, jtiger, jkate)

Thanks in advance,

Octavi