a tip about how to extract .SWFfile from PowerPoint file
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From: SusanZheng on 2 Nov 2005 04:25 Hi, I saw an artical about how to extract .swf from PPT files and think it's quite useful, hope it helps. --------------------------------------------- We had a Power Point Presentation file given us a few days ago with an embedded flash file which we needed to extract to use on the website. We couldn't find any way to do this. We could drag and drop the swf onto another presentation, we could even drag the object onto the desktop. This created a scrap file which was rather annoying. However, this led me to the discovery of the NeverShowExt registry key. I managed to rename the scrap to a have a .swf extension, but still no cookie. So I started digging around the scrap to see if I could find the swf object inside and after reading an introduction to SWF I found what I was looking for. Now I just wanted to extract this binary data from the scrap file, and I wanted to do it the hard way! So I wrote a small amount of code to look through a file and extract the goodies. The main part of the code was to take a byte array and copy that into my SWF struct - using the System.Runtime.InteropServices.Marshal class. After a bit of messing around the code runs like a dream. The final executable takes 2 parameters the first is the file containing the SWF and the second is the file to write the SWF. using System; using System.IO; using System.Runtime.InteropServices; namespace FlashExtractor { /// <summary> /// Summary description for Class1. /// </summary> class Class1 { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main(string[] args) { //assume param 1 is the location of the shockwave file byte[] file = new byte[Marshal.SizeOf(typeof(swf))]; FileStream fs = File.Open(args[0], FileMode.Open, FileAccess.Read,FileShare.Read); int i=0; //go through the file byte by byte //could I have seeked this? while (i<fs.Length-8) { //set the position in the file fs.Position = i; //read off 8 bytes worth of data to put into the swf struct fs.Read(file,0, 8); IntPtr ptr = Marshal.AllocHGlobal(file.Length); Marshal.Copy(file, 0x0, ptr, file.Length); swf s = (swf) Marshal.PtrToStructure(ptr, typeof(swf)); // if the struct header is FWS then we may have a flash file if (s.header1==0x46 && s.header2==0x57 && s.header3==0x53) { //we have the identity of a flash file Console.WriteLine("Found the header of a flash file"); Console.WriteLine("Version: {0}", s.version); Console.WriteLine("Size: {0}", s.size); //if the size of the fws is < length of the file if (s.size + i<=fs.Length) { Console.WriteLine("Attempting to write the file to {0}", args[1]); FileStream fw = File.OpenWrite(args[1]); Console.WriteLine("Allocation byte array of {0} length", s.size); byte[] b=new byte[s.size]; Console.WriteLine("Reseting the file back to position: {0}", i); fs.Position = i; Console.WriteLine("Reading from {0} to {1}", i, s.size); fs.Read(b,0,(int)s.size); Console.WriteLine("Writing byte array back to disk"); fw.Write(b, 0, b.Length); fw.Close(); break; } else { Console.WriteLine("The file is not of the correct size file: {0}, {1}", s.size, fs.Length); } } i++; } fs.Close(); } } [StructLayout (LayoutKind.Sequential, Pack = 0x1)] struct swf { public byte header1; public byte header2; public byte header3; public byte version; public UInt32 size; } } In theory this could be used to extract many forms of embedded binary data. --------------------------------------- http://www.sameshow.com A practical yet easy-to-use software to convert PowerPoint to Flash for publishing on Web or emailing to others -- SusanZheng
From: Echo S on 2 Nov 2005 22:58
This is a very nice tip. Here's the link to the article you saw. http://www.hairy-spider.com/CommentView,guid,ae35144c-2977-4c0f-8e86-3515ee7b1121.aspx It's generally good form to add links to information that you didn't actually write. -- Echo [MS PPT MVP] http://www.echosvoice.com "SusanZheng" <SusanZheng.1xv4tm(a)news.officefrustration.com> wrote in message news:SusanZheng.1xv4tm(a)news.officefrustration.com... > > Hi, I saw an artical about how to extract .swf from PPT files and think > it's quite useful, hope it helps. > --------------------------------------------- > We had a Power Point Presentation file given us a few days ago with an > > embedded flash file which we needed to extract to use on the website. > > > We couldn't find any way to do this. We could drag and drop the swf > onto another presentation, we could even drag the object onto the > desktop. This created a scrap file which was rather annoying. > > > However, this led me to the discovery of the NeverShowExt registry key. > > I managed to rename the scrap to a have a .swf extension, but still no > > cookie. > > > So I started digging around the scrap to see if I could find the swf > object inside and after reading an introduction to SWF I found what I > was looking for. > > > Now I just wanted to extract this binary data from the scrap file, and > > I wanted to do it the hard way! > > > So I wrote a small amount of code to look through a file and extract > the goodies. The main part of the code was to take a byte array and > copy that into my SWF struct - using the > System.Runtime.InteropServices.Marshal class. > > > After a bit of messing around the code runs like a dream. The final > executable takes 2 parameters the first is the file containing the SWF > > and the second is the file to write the SWF. > > > using System; > using System.IO; > using System.Runtime.InteropServices; > > > namespace FlashExtractor > { > /// <summary> > /// Summary description for Class1. > /// </summary> > class Class1 > { > /// <summary> > /// The main entry point for the application. > /// </summary> > [STAThread] > static void Main(string[] args) > { > //assume param 1 is the location of the > shockwave file > byte[] file = new > byte[Marshal.SizeOf(typeof(swf))]; > > > FileStream fs = File.Open(args[0], > FileMode.Open, > FileAccess.Read,FileShare.Read); > int i=0; > //go through the file byte by byte > //could I have seeked this? > while (i<fs.Length-8) > { > //set the position in the file > fs.Position = i; > //read off 8 bytes worth of data to put > into the swf > > struct > fs.Read(file,0, 8); > IntPtr ptr = > Marshal.AllocHGlobal(file.Length); > Marshal.Copy(file, 0x0, ptr, > file.Length); > swf s = (swf) > Marshal.PtrToStructure(ptr, typeof(swf)); > > > // if the struct header is FWS then we > may have a flash > > file > if (s.header1==0x46 && s.header2==0x57 > && > > s.header3==0x53) > { > //we have the identity of a > flash file > Console.WriteLine("Found the > header of a flash > > file"); > Console.WriteLine("Version: > {0}", s.version); > Console.WriteLine("Size: {0}", > s.size); > > > //if the size of the fws is < > length of the file > if (s.size + i<=fs.Length) > { > > Console.WriteLine("Attempting to write > > the file to {0}", > args[1]); > FileStream fw = > File.OpenWrite(args[1]); > > > > Console.WriteLine("Allocation byte array > > of {0} length", s.size); > byte[] b=new > byte[s.size]; > > > > Console.WriteLine("Reseting the file > > back to position: {0}", i); > fs.Position = i; > > > > Console.WriteLine("Reading from {0} to > > {1}", i, s.size); > > fs.Read(b,0,(int)s.size); > > > > Console.WriteLine("Writing byte array > > back to disk"); > fw.Write(b, 0, > b.Length); > > > fw.Close(); > break; > } > else > { > Console.WriteLine("The > file is not of > > the correct size file: {0}, > {1}", s.size, fs.Length); > } > > > } > i++; > } > fs.Close(); > > > } > > > } > > > [StructLayout (LayoutKind.Sequential, Pack = 0x1)] > struct swf > { > public byte header1; > public byte header2; > public byte header3; > public byte version; > public UInt32 size; > } > > > > } > > > In theory this could be used to extract many forms of embedded binary > data. > --------------------------------------- > http://www.sameshow.com > A practical yet easy-to-use software to convert PowerPoint to Flash for > publishing on > > Web or emailing to others > > > -- > SusanZheng |