Re: How do I extract an embeded flash movie from PowerPoint?
- From: yang572033@xxxxxxxxx
- Date: 22 Nov 2005 23:39:00 -0800
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
---------------------------------------
.
- References:
- Re: How do I extract an embeded flash movie from PowerPoint?
- From: Troy @ TLC Creative
- Re: How do I extract an embeded flash movie from PowerPoint?
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