Editable Adobe Flash movies (.fla) can be converted to Shockwave flash (.swf) usually with any software that deal with Flash graphics, or even some dedicated SWF software. These .fla files should not be confused with FLAC audio, that also occasionally uses the FLA extension. But even such fla to swf conversion might be possible, but would be related to some kind of import of audio to flash multimedia content.
Open FLA file Open SWF fileMultimedia platform for Mac used to add animation, video, and interactivity to web pages
An old SWF to FLA converter