Ravi Kiran
March 25th, 1999, 07:03 AM
Hi Gurus,
Can you tell me the where i can find the format of a 'Jpeg' file?
ie. BMP has a certain format of storing data. similarly Jpeg should also have.
I want to be able to convert an (3rd party) existing Jpeg format, to be displayed be a typical VB app.
Can anyone help, please? Any help on algorithms/dlls/ActiveX-servers will be appreciated. (But not complete products please!, I can't plug-in a Abode PhotoStop into my program :-) )
Thanks in advance...
Ravi
Chris Eastwood
March 29th, 1999, 09:19 AM
Hi Ravi
I've been looking for this URL for ages - I lost all my 'favorites' a while back and my memory's not what it, er, used to be.
Take a look at :
http://www.wotsit.org/index.htm
They have the format/layout/specification for just about any file format you could be interested in.
(I'm going to add a link from the CodeGuru page to this site)
Regards
Chris Eastwood
CodeGuru - the website for developers
http://www.codeguru.com/vb
Ravi Kiran
March 29th, 1999, 09:42 PM
Hi Chris,
Over the weekend, i have downloded the whole set of Jpeg group's original Jpeg coding-decoding 'C' code library along with 2 sample programs. This same site is also recomemded by one of the links in www.wotsit.org .
I see myself spending atleast a couple of weeks before i get anything to work :-)
As an aside, if you are interested, i will brief my problem. Throw me some ideas!.
I have a vedio-capture board that supports recording & playback at good speeds ~30F/s also. Since there is no standard as such like "M-Jpeg", the board maker compresses each frame as a Jpeg, and saves all of them in one file. Since the playback is tied to the h/w, my client want me to develop a s/w option also, and he is willing to forgo speed & realistic playback. Obviously he has to.
I have contacted the board maker & got the details of the vender-specific tags etc in the "M-jpeg" file. I *wrote* a s/w that breaks up the original file ~30MB into Frames, save each as a sep.files(~600files for a typical recording!) and use VB's internal support for Jpeg file display to show the frames. AND It works!. On my development machine (300MHz, P-II, 128MB), at 15F/s rec.speed there is no difference between h/w & s/w playback. At higher f/s, s/w playback looks like in slow-motion , but it is ok.
The problem is : I have no facility to control anything in this process.
Before the beta testing i was wondering what will i do if i get some problem. and lo, it comes: The clients machine's disk IO is not as fast as my devel.machine; since it is not able to write to the disk as fast as it should , the board seems to skip some data. The h/w maker confirms this.
When the same file is played back using the h/w, it is able to manage the missing portions. But when i use my s/w playback program, the VB program hangs!!. and at specific files/frames only.
When i use IE/other Jpeg viewing s/w to view this (frame)file alone it comeout ok. So it is asif the necessary image data for the frame exists, somewhere deep inside but VB is not able to pick it up. As a test, when i use load this file as a frame's picture property even in IDE, the VB hangs!
So here i want to know the Jpeg format, atleast to assert that the file is of correct type & if possible prune/cutoff the unnecessary data for each frame.
I have looked at 'Wang Imaging' controls and IE in automation mode & Webbrowser control to display these frames. The former has an annoying flicker & mouse cursor change, and the later has perceptible gap between frames when it clears the image & displays "here-image-will-come" icon of IE.
VB's support is clean, and as required but for this problem.
I would really appreciate any ideas on this.
Ravi
ps: Is it ok, to pose specific problems like this on this discussion board ?
If not so please let me know, i will not ask next time. Sorry.
Chris Eastwood
March 31st, 1999, 05:33 AM
Hi Ravi
I've never coded anything like this before (I'm just a humble business-app developers).
You may find something to help you at :
http://i.am/shrinkwrapvb
The site covers some pretty advanced multi-media techniques, including source-code for video capture (which may interest you!).
Let me know how you get on - it may be worth an article on the CodeGuru site !
As for posting a question like this on the board - that's what it's all about !
Good Luck
Chris Eastwood
CodeGuru - the website for developers
http://www.codeguru.com/vb/bbs
VB MultiMedia Site