Re: webcamasm

To help out in the discussion of video cameras and getting and
establishing a video connection, We start off exploring avicap32.dll.
We go through it's exports, then some imports. We take a look at
the date/time stamps on some files and some conclusions get drawn.
There are some interesting things in the imports and more specifically
two specific files that provide those functions. It all ends up as a brief
overview and some particular assertions about the files employed to
make a video connection and connect to the drivers.

Some of this might help John. I don't know how far he's dug into
it all.

I know nothing of this topic, personally, so take what you can out of it.

I end the message with a list of the tools I used.

Directory of %systemroot%\system32

08/23/2001 08:00 AM 69,584 avicap.dll
08/23/2001 08:00 AM 64,000 avicap32.dll
08/04/2004 12:56 AM 84,992 avifil32.dll
08/23/2001 08:00 AM 109,456 avifile.dll
4 File(s) 328,032 bytes

The machine is Windows XP SP2. The dates on the avicap*.dll
files indicate (guessing) that those are just simple files that leave the
dirty work to other files. We look at the imports to see what's going
on. The exports are few and kind of indicate that they deal with a high
level aspect. First, the avicap*.dll files do not get updated. The files
that do get updated are the files that do the work.

.............
avicap32.dll
.............
Dump of file avicap32.dll

Section contains the following exports for AVICAP32.dll

0 characteristics
3B7D6CA2 time date stamp Fri Aug 17 15:12:34 2001
0.00 version
1 ordinal base
6 number of functions
6 number of names

ordinal hint RVA name

1 0 0000BCAC AppCleanup
2 1 00001E3B capCreateCaptureWindowA
3 2 00001DEB capCreateCaptureWindowW
4 3 00001B0F capGetDriverDescriptionA
5 4 00001B06 capGetDriverDescriptionW
6 5 0000C3A5 videoThunk32

There are very few exports. So we take a look at the imports for
avicap32.dll to see if that provides any help.

MSVFW32.dll
73B8117C Import Address Table
73B8C8D4 Import Name Table
FFFFFFFF time date stamp
FFFFFFFF Index of first forwarder reference

73BD5632 26 ICSeqCompressFrame
73BD55A7 27 ICSeqCompressFrameEnd
73BD17C3 3 DrawDibDraw
73BD5393 28 ICSeqCompressFrameStart
73BD33D8 6 DrawDibGetPalette
73BD2304 0 DrawDibBegin
73BD5979 1D ICImageDecompress
73BD3EED 7 DrawDibOpen
73BD52E8 16 ICCompressorFree
73BD8BFF 2 DrawDibClose
73BD6E8C 15 ICCompressorChoose
73BD2260 9 DrawDibRealize

WINMM.dll
73B8126C Import Address Table
73B8C9C4 Import Name Table
FFFFFFFF time date stamp
FFFFFFFF Index of first forwarder reference

76B43196 C SendDriverMessage
76B42D39 8 OpenDriver
76B43380 0 CloseDriver
76B4B0C1 88 mmioDescend
76B4AD8B 8F mmioRead
76B563B8 41 mciSendStringW
76B4B389 85 mmioAscend
76B4B20D 8E mmioOpenW
76B4AEA4 86 mmioClose
76B4B5FA 98 mmioWrite
76B5A4E1 B3 waveInStart
76B5A516 B4 waveInStop
76B43DF7 BD waveOutGetNumDevs
76B4B578 87 mmioCreateChunk
76B4AC55 89 mmioFlush
76B5A54B B2 waveInReset
76B5A3F7 B5 waveInUnprepareHeader
76B5A2D8 A7 waveInClose
76B46ACA B0 waveInOpen
76B5A387 B1 waveInPrepareHeader
76B5A47F A6 waveInAddBuffer
76B41B40 A3 timeGetTime
76B4ACDB 92 mmioSeek

08/04/2004 12:56 AM 120,832 msvfw32.dll
08/04/2004 12:56 AM 176,128 winmm.dll

Sure enough, those are the dirty work files, while avicap*.dll
provide some sort of convenient functions for high-level
programmers. At least that's the way I'm reading it.

The winmm.dll looks like it provides some interesting functions,
OpenDriver()
CloseDriver()
SendDriverMessage()

I used dumpbin.exe to provide that information. Now we need to
get to some more help about the functions. Can I use dumpbin to
get a disassembly of a specific function? There are some other tools
out there that provide some help, but MASM32 offers some help,
but nothing as far as avicap* goes.

MASM32 has some prototypes in winmm.inc.

OpenDriver PROTO :DWORD,:DWORD,:DWORD
CloseDriver PROTO :DWORD,:DWORD,:DWORD
SendDriverMessage PROTO :DWORD,:DWORD,:DWORD,:DWORD

And then there is PEID.

PEID ( http://peid.has.it/ )

provides helpful information about the files.

--
Jim Carlock
Custom Designed Swimming Pools
http://www.aquaticcreationsnc.com/swimming/pool/builder/nc/viewing1.php


.