as3swf is a low level Actionscript 3 library to parse, create, modify and publish SWF files. Using its API, you can produce an object dump of the SWF that shows several statistics about its content.
If the analyzed SWF has a rectangle, for instance, the dump shows an additional
DefineShape tag (which defines the geometry and style of the rectangular shape) along with a
PlaceObject tag (which places the previously defined shape on the display list at a certain depth).
import com.codeazur.as3swf.SWF; var swf:SWF = new SWF(root.loaderInfo.bytes); trace(swf); // Produces the following dump: [SWF] Version: 10, FileLength: 147508, FileLengthCompressed: 147508, FrameSize: (550,400), FrameRate: 24, FrameCount: 1, Tags: 7 Tags: [69:FileAttributes] AS3: true, HasMetadata: false, UseDirectBlit: false, UseGPU: false, UseNetwork: false [09:SetBackgroundColor] Color: #FFFFFF [86:DefineSceneAndFrameLabelData] Scenes:  Offset: 0, Name: Scene 1 [82:DoABC] Lazy: true, Length: 147408 [76:SymbolClass] Symbols:  TagID: 0, Name: Untitled_fla.MainTimeline [01:ShowFrame] [00:End]