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I tried to look for free H.264 editors that could do such forementioned tasks, but i couldn't find any suitable results (probably due to my incorrect(?) search terms).
Basically, i have quite a few 20 to 40 second looping movie files (rendered with Adobe Premiere), and i would like to multiply an individual movie to about ten or twenty fold, and then save it again, preferably without the need to re-render (or re-encode?). Is this possible?
Hopefully i managed to make myself understood, thanks :)
After a whole bunch of searching and testing, i ended up with Avidemux and it did the task perfectly, this time around. I'm sure there would've been a way to automatize the appending / "multiplying" of the file, but with a tablet pen (main click set as double click) and specific folder it truly went by like a breeze.
I was also interested of Smart Cutter (i quite enjoyed the interface after getting used to it), but since it was trialware the choice was clear. Still, if i would have to do these kind of tasks more often, i might consider purchasing it.
Today my co-worker noticed that when adding a decimal place to a progress indicator leads to the impression that the program is running faster than without. (i.e. instead of 1,2,3... it shows 1, 1.2, 1.4, 1.6, ...) I checked it and I was surprised that I got the same impression even though I knew it was faked.
That makes me wonder: What other things are there to create the impression of a fast application?
Of course the best way is to actually make the application faster, but from an algorithmic point of view often there's not much you can do. Additionally I think making a user less frustrated is a good thing, even though it is more or less a psychologic trick.
This effect can be very dramatic: doing relatively large amounts of work to give users a correct and often updating status of progress can of course slow down the actual running time of the application (screen updates, progress display needed calculations, etc) while still giving the user the feeling it takes less time.
Some of the things you could do in GUIs:
make sure your application remains responsive (resizing the forms remains possible, perhaps give a cancel button for the operation?) while background processing is occurring
be very consistent in showing status messages/hourglass cursors throughout the application
if you have something updating during an operation, make sure it updates often (like the almost ridiculous showing of filenames and registry keys during an install), or make sure there's an option to make it do this for users that like this behavior
Present some intermediate, interesting results first. "We've found 2,359 zetuyls matching your request, we're just calculating their future value".
I've seen transport reservation systems do that sort of thing quite nicely.
Showing details (such as the names of files being copied in an installation process) can often make things seem like they're going faster because there's constant, noticeable activity (as opposed to a slowly-creeping progress bar).
If your algorithm is such that it generates a list of results, and you have some way of displaying results as they're generated (as opposed to all at once at the end), do so - the sooner the user has something else to look at besides a spinner, the better.
Allow the user to do something else, while your application is processing data or waiting for a result. In application-scope you could allow to do some refinement of a search query or collect information for preparing next steps. Or just present some other "work" necessary to do or just some hints, documentation, statistics, entertainment..
Use one of those animated progress bars which look like they are doing something even when they aren't progressing. Also, as peSHIr said - print each filename that you copy and update it really fast - you could even fake it by cycling through a large string array N times a second.
I've read somewhere that if the process seems to be speeding up, it seems to be faster than when it's progressing at a steady pace. I can't find the reference right now, but it should be simple to implement.
(10 minutes later...)
A further look down Google lane unearthed the following references:
http://www.azarask.in/blog/post/hacking-memory/
http://blogs.msdn.com/time/
Here is an article about "Expressing time in your UI" and user perception of time. I do not know if it is exactly what you expect as an answer, but it is definitely worth the read.
Add a thread sleep at critical points. With each passing version, reduce the delay.
I'm in the process of going back over some of the more minor TODO's in my code. One of them is in a class that handles partial dates, e.g. Jan 2001. It works fine for dates that will be seen in our system (1990 - 2099) and gracefully fails for other dates.
The TODO that I've left for myself is that I don't handle dates in the century 2100 and beyond. I don't really think it worth the effort fixing this particular problem, but I am cognisant of the Y2k bugs. If we were in 2080 already I think I'd be thinking differently and would fix the bug.
So how long does code last for? How far ahead should we plan for our systems to keep running for?
Update
Ok, thanks for all your input. I think I'm going for the option of leave the TODO in the code and do nothing. The thoughts I found most interesting were:
#Adrian - Eternity, I think that's the most correct assumption, your point about VM's is a good one.
#jan-hancic - It depends, yes it does.
#chris-ballance - I'm guessing I'll be dead by the time this restriction is hit, so they can come defile my grave if they want, but I'll be dead, so I'll just haunt his ass.
The reason I decided to do nothing was simple. It added negligable business value, the other things that needed looking at did add value so I'll do them first and if I get the time I'll fix it, but really it'll be nothing more than an academic exercise.
Longer than you expect.
Eternity.
Given the trend that old system keep running in virtual machines, we must assume that all useful code will run forever. There are many system that run since the 60ies, eg backend code in financial sector, and there seems to be no indication that these systems will ever get replaced. (And in the meantime, the frontend is being replaced every other year with the latest fad in web technology. So, the closer your code is to the core of your system, the more likely it will run forever.)
You can't have a general answer here. Depends on what kind of project you are building.
If you are writing software for a space probe then you might want to code it so that it will work for the next 100 years and more.
But if you are programming a special Xmas offer for your company's web page, a few weeks should be enough ...
Assume that whoever will maintain the code is a psychopath and has your home address.
Nobody really knows. Professional programming has been around for 30-40 years, so nobody really knows if code is going to last for 100 years. But if the Y2K bug is an indication, it is that a lot of code is going to stick around for a lot longer than the programmer intended. Keep in mind that even if you take that into account, it could still stick around longer than you expected. No matter how much you prepare, it might still outlive it's intended life expectancy.
My advice is to not plan for code to last 100 years. Instead try to make sure all your code will work for the same length of time, that is, part of it should not fail in 2 years, while the other part should fail in 100 years. Remember, you should always fix the weakest link first, so there is no point making the strongest link stronger.
Sometimes, code lasts longer than you think. But, more important is the slippery slope argument. Once you forgive yourself a bit of non-bullet-proofness, you may be tempted to optimize further and skimp on logical correctness, until it finally bites you.
By the way, I recommend to have an issue ID (such as FogBugz case number) in every TODO comment, so that people can actually subscribe to and track this TODO.
in Dan Bernstein's immortal words: Don't contribute to the Y10K problem!
I don´t think the code will last so long.
Think about all the inventions and progress made in the last 90 years.
In 2100 we won´t have to write down code.
There will be some kind of brain-machine interface.
Well, we recently made a timestamp format where time is stored in a unsigned 64-bit integer as microseconds from 1970. It will last until the year 586912, which should be enough.
Coding for "forever" is unnecessary - of course you could use BigIntegers and such everywhere, but why? Just be prepared for more than 5 or 10 years. Twenty year old production code is not quite unusual nowadays, and I suspect that the average life cycle will get even longer in the near future.
It depends on how much business value the code has and how much resources it takes to write it from scratch. The more value and resources the longer it lasts. Ten years and more is typical for commercial "works, don't touch it" code.
I always tried to code like my applications must work "forever". I am very sure I wont be around anymore in 2100 but knowing my software has a build in expiration date doesn't make me feel good. If you know about such things try to avoid them! You will never know but some unknown programmer in the future may be grateful.
Right up until the time that it breaks, or otherwise ceases to be useful, and then for a bit longer after that
The essential things are:
How good is your internal date class (get a very robust library version and stick to it!)
It's not just the passage of time, but also the growth in the range of inputs your users want. For example, maybe you have 30 year mortgage inputs now, but next month someone decides to input a 99 year lease with maturity 2110, or a 100 year Disney bond!
If you accept 2 digit year inputs with a date window, think very carefully about how that is applied to start and end dates, and give lots of immediate feedback.
Here are my two cents:
When we design a project, we usually declare it to last "at least" 5 years. Usually no more than 10 years before we re-design it and build it all over. (We're talking about mid-large size projects here).
What usually happens is that the new project you build is supposed to replace the old one, either techonology wise (i.e. moving from MF to windows, VB to .net etc.), but this project never ends. So your client ends up working with 2 systems at once and that leftover system is what later is referred to as "legacy".
If you wait long enough, a third project will rise causing the client to work with 3 systems at once and so on...
But to answer your question, I would bet on 5-10 years before redesign, and unless your dates are supposed to be long into the future - no need to worry about the 2100 limitation.
IMHO it comes down to craftmanship : the pride we take in our work, coding to a standard we would not be ashamed another real coder to see.
In the case of dates like this, you've stated that it gracefully fails after 2100. This sounds like you can remove the TODO without a bad conscience, because you have built in a response that will allow the cause of failure to be easily diagnosed and fixed in the (however likely or unlikely) circumstance that a failure occurs.
There are examples of code running on older machines which is 40 or 50 years old.
(Interesting bits in this thread: http://developers.slashdot.org/developers/08/05/11/1759213.shtml).
You've got to ask yourself about the nature of the problem you're solving but generally speaking even "quick fixes" will be around for years so you could realistically be looking at a decade or more for code intended to have a decent shelf life.
The other things you need to think about is:
1) What is the "active life" of the application - that is where it's going to be used and processing.
2) What is the "inactive life" of the application - that is it's not going to be used day to day but might be used for retrieving and viewing old records. For instance UK audit law means that records need to be available for 7 years, so that's potentially 7 years from last system use.
3) What is the range of future data it needs to handle? For instance say you're taking down credit card expiry dates - you can have a card which won't expire for a decade. Can you handle that date?
The answers to these questions will generally lead you to the assumption that you should never knowingly write code which has date constraints beyond those the OS/Language you're using dictates.
The question isn't "How long does code last?" but rather "How long will things in my code affect an application?"
Even if your code is replaced, it's possible that it will get replaced with code that does the exact same thing. To some extent, this is the direct cause of the Y2K problem. More to the point, it is the direct cause of the Y2038 problem.
Also keep in mind what you mean by last.
For example, the original UNIX operating was developed 30 years ago. But during that 30 years, the product has evolved over time.
Though, it wouldn't surprise me if a little but of original code still exists in it today.
So think of it 2 ways ... 1) do you ever antisipate the code being touched in the future, 2) the product/code will evolve if you have support and involvmment.
My current shop has a large code base that runs financial applications with complex business rules. Some of these rules are encoded in stored procedures, some in triggers, and some in 3gl and 4gl application code. There is running code from the late 90's, and none of it in your "traditional" Legacy languages like COBOL or FORTRAN. As one could imagine, it's a steaming pile of spaghetti code, most created before TDD meant anything, so people are reluctant to touch anything.
I have had occasion to be brought in on contract more than a decade after the fact to consult on porting code to a new platform (OS/2 just isn't that popular these days!). When in doubt, assume that your code will live longer than you will. At the very least, document the heck out of limitations like this; fix them unless that takes tremendously more work than to document them.
In 1995 I started work at a new job, on an 8 year old code base.
So it's incept date was 1987 or thereabouts.
The code is probably still in service. Thats what ? 23 years.
There's been some moves of the company, but they probably kept the software ( because it works)
If it's still in service now, it will still be in service in a decade or so.
It's not surprising, particularly high tech code, in C (mostly)
In 1999 I started at a new job, the the codebase had antecedents back to 1984.
The new version I designed in the 2000's is still in service, with design elements like data file formats from the previous one ( and so on back) and that would be a development program over 26 years.
So the year 2086 problem is starting to loom a little as those 32 bit signed time_t's roll over.
Remember that one of the major bonuses of modern programming is reuse.
So that means the code you write originally to solve one problem may get re-purposed and used in a completely different scenario years later (maybe even without your knowledge, by a team mate).
As a side note:
One of the major pluses of automated unit testing, is testing code that you can't even remember is there in a system! :)
As long as people can continue to bill for support with people willing to pay for it.
3-5 years max. After that you have moved on to another job and left your crappy code behind.
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Sometimes you don't have the source code and need to reverse engineer a program or a black box. Any fun war stories?
Here's one of mine:
Some years ago I needed to rewrite a device driver for which I didn't have source code. The device driver ran on an old CP/M microcomputer and drove a dedicated phototypesetting machine through a serial port. Almost no documentation for the phototypesetting machine was available to me.
I finally hacked together a serial port monitor on a DOS PC that mimicked the responses of the phototypesetting machine. I cabled the DOS PC to the CP/M machine and started logging the data coming out of the device driver as I feed data in through the CP/M machine. This enabled me to figure out the handshaking and encoding used by the device driver and re-create an equivalent one for a DOS machine.
Read the story of FCopy for the C-64 here:
Back in the 80s, the Commodore C-64 had an intelligent floppy drive, the 1541, i.e. an external unit that had its own CPU and everything.
The C-64 would send commands to the drive which in turn would then execute them on its own, reading files, and such, then send the data to the C-64, all over a propriatory serial cable.
The manual for the 1541 mentioned, besides the commands for reading and writing files, that one would read and write to its internal memory space. Even more exciting was that one could download 6502 code into the drive's memory and have it executed there.
This got me hooked and I wanted to play with that - execute code on the drive. Of course, there was no documention on what code could be executed there, and which functions it could use.
A friend of mine had written a disassembler in BASIC. and so I read out all its ROM contents, which was 16KB of 6502 CPU code, and tried to understand what it does. The OS on the drive was quite amazing and advanced IMO - it had a kind of task management, with commands being sent from the communication unit to the disk i/o task handler.
I learned enough to understand how to use the disk i/o commands to read/write sectors of the disc. Actually, having read the Apple ]['s DOS 3.3 book which explained all of the workings of its disk format and algos in much detail, was a big help in understanding it all.
(I later learned that I could have also found reserve-eng'd info on the more 4032/4016 disk drives for the "business" Commodore models which worked quite much the same as the 1541, but that was not available to me as a rather disconnected hobby programmer at that time.)
Most importantly, I also learned how the serial comms worked. I realized that the serial comms, using 4 lines, two for data, two for handshake, was programmed very inefficiently, all in software (though done properly, using classic serial handshaking).
Thus I managed to write a much faster comms routine, where I made fixed timing assumtions, using both the data and the handshake line for data transmission.
Now I was able to read and write sectors, and also transmit data faster than ever before.
Of course, it would have been great if one could simply load some code into the drive which speeds up the comms, and then use the normal commands to read a file, which in turn would use the faster comms. This was no possible, though, as the OS on the drive did not provide any hooks for that (mind that all of the OS was in ROM, unmodifiable).
Hence I was wondering how I could turn my exciting findings into a useful application.
Having been a programmer for a while already, dealing with data loss all the times (music tapes and floppy discs were not very realiable back then), I thought: Backup!
So I wrote a backup program which could duplicate a floppy disc in never-before seen speed: The first version did copy an entire 170 KB disc in only 8 minutes (yes, minutes), the second version did it even in about 4.5 minutes. Whereas the apps before mine took over 25 minutes. (Mind you, the Apple ][, which had its disc OS running on the Apple directly, with fast parallel data access, did this all in a minute or so).
And so FCopy for the C-64 was born.
It became soon extremely popular. Not as a backup program as I had intended it, but as the primary choice for anyone wanting to copy games and other software for their friends.
Turned out that a simplification in my code, which would simply skip unreadable sectors, writing a sector with a bad CRC to the copy, did circumvent most of the then-used copy protection schemes, making it possible to copy most formerly uncopyable discs.
I had tried to sell my app and sold it actually 70 times. When it got advertised in the magazines, claiming it would copy a disc in less than 5 minutes, customers would call and not believe it, "knowing better" that it can't be done, yet giving it a try.
Not much later, others started to reverse engineer my app, and optimize it, making the comms even faster, leading to copy apps that did it even in 1.5 minutes. Faster was hardly possible, because, due to the limited amount of memory available on the 1541 and the C-64, you had to swap discs several times in the single disc drive to copy all 170 KB of its contents.
In the end, FCopy and its optimized successors were probably the most-popular software ever on the C-64 in the 80s. And even though it didn't pay off financially for me, it still made me proud, and I learned a lot about reverse-engineering, futility of copy protection and how stardom feels. (Actually, Jim Butterfield, an editor for a C-64 magazine in Canada, told its readers my story, and soon he had a cheque for about 1000 CA$ for me - collected by the magazine from many grateful users sending 5$-cheques, which was a big bunch of money back then for me.)
I actually have another story:
A few years past my FCopy "success" story, I was approached by someone who asked me if I could crack a slot machine's software.
This was in Germany, where almost every pub had one or two of those: You'd throw some money in what amounts to about a US quarter, then it would spin three wheels and if you got lucky with some pattern, you'd then have the choice to "double or nothing" your win on the next play, or get the current win. The goal of the play was to try to double your win a few times until you'd get in the "series" mode where any succeeding win, no matter how minor, would get you a big payment (of about 10 times your spending per game).
The difficulty was to know when to double and when not. For an "outsider" this was completely random, of course. But it turned out that those German-made machines were using simple pseudo-randomized tables in their ROMs. Now, if you watched the machine play for a few rounds, you'd could figure out where this "random table pointer" was and predict its next move. That way, a player would know when to double and when to pass, leading him eventually to the "big win series".
Now, this was already a common thing when this person approached me. There was an underground scene which had access to the ROMs in those machines, find the tables and create software for computers such as a C-64 to use for prediction of the machine's next moves.
Then came a new type of machine, though, which used a different algorithm: Instead of using pre-calc'd tables, it did something else and none of the resident crackers could figure that out. So I was approached, being known as a sort of genius since my FCopy fame.
So I got the ROMs. 16KB, as usual. No information on what it did and how it worked whatsoever. I was on my own. Even the code didn't look familiar (I knew 6502 and 8080 by then only). After some digging and asking, I found it was a 6809 (which I found to be the nicest 8 bit CPU to exist, and which had analogies to the 680x0 CPU design, which was much more linear than the x86 family's instruction mess).
By that time, I had already a 68000 computer (I worked for the company "Gepard Computer" which built and sold such a machine, with its own developer OS and, all) and was into programming Modula-2. So I wrote a disassembler for the 6809, one that helped me with reverse engineering by finding subroutines, jumps, etc. Slow I got a an idea of the flow control of the slot machine's program. Eventually I found some code that looked like a mathmatical algorithm and it dawned on me that this could be the random generating code.
As I never had a formal education in computer sciences, up to then I had no idea how a typical randomgen using mul, add and mod worked. But I remember seeing something mentioned in a Modula-2 book and then realized what it was.
Now I could quickly find the code that would call this randomgen and learn which "events" lead to a randomgen iteration, meaning I knew how to predict the next iterations and their values during a game.
What was left was to figure out the current position of the randomgen. I had never been good with abstract things such as algebra. I knew someone who studied math and was a programmer too, though. When I called him, he quickly knew how to solve the problem and quabbled a lot about how simple it would be to determine the randomgen's seed value. I understood nothing. Well, I understood one thing: The code to accomplish this would take a lot of time, and that a C-64 or any other 8 bit computer would take hours if not days for it.
Thus, I decided to offer him 1000 DM (which was a lot of money for me back then) if he could write me an assembler routine in 68000. Didn't take him long and I had the code which I could test on my 68000 computer. It took usually between 5 and 8 minutes, which was acceptable. So I was almost there.
It still required a portable 68000 computer to be carried to the pub where the slot machine stands. My Gepard computer was clearly not of the portable type. Luckly, someone else I knew in Germany produced entire 68000 computers on a small circuit board. For I/O it only had serial comms (RS-232) and a parallel port (Centronics was the standard of those days). I could hook up some 9V block battieries to it to make it work. Then I bought a Sharp pocket computer, which had a rubber keyboard and a single-line 32 chars display. Running on batteries, which was my terminal. It had a RS-232 connector which I connected to the 68000 board. The Sharp also had some kind of non-volatile memory, which allowed me to store the 68000 random-cracking software on the Sharp, transfer it on demand to the 68000 computer, which then calculated the seed value. Finally I had a small Centronics printer which printed on narrow thermo paper (which was the size of what cash registers use to print receipts). Hence, once the 68000 had the results, it would send a row of results for the upcoming games on the slot machine to the Sharp, which printed them on paper.
So, to empty one of these slot machines, you'd work with two people: You start playing, write down its results, one you had the minimum number of games required for the seed calculation, one of you would go to the car parked outside, turn on the Sharp, enter the results, it would have the 68000 computer rattle for 8 minutes, and out came a printed list of upcoming game runs. Then all you needed was this tiny piece of paper, take it back to your buddy, who kept the machine occupied, align the past results with the printout and no more than 2 minutes later you were "surprised" to win the all-time 100s series. You'd then play these 100 games, practically emptying the machine (and if the machine was empty before the 100 games were played, you had the right to wait for it to be refilled, maybe even come back next day, whereas the machine was stopped until you came back).
This wasn't Las Vegas, so you'd only get about 400 DM out of a machine that way, but it was quick and sure money, and it was exciting. Some pub owners suspected us of cheating but had nothing against us due to the laws back then, and even when some called the police, the police was in favor of us).
Of course, the slot making company soon got wind of this and tried to counteract, turning off those particular machines until new ROMs were installed. But the first few times they only changed the randomgen's numbers. We only had to get hold of the new ROMs, and it took me a few minutes to find the new numbers and implement them into my software.
So this went on for a while during which me and friends browsed thru pubs of several towns in Germany looking for those machines only we could crack.
Eventually, though, the machine maker learned how to "fix" it: Until then, the randomgen was only advanced at certain predictable times, e.g. something like 4 times during play, and once more per the player's pressing of the "double or nothing" button.
But then they finally changed it so that the randomgen would continually be polled, meaning we were no longer able to predict the next seed value exactly on time for the pressing of the button.
That was the end of it. Still, making the effort of writing a disassembler just for this single crack, finding the key routines in 16KB of 8 bit CPU code, figuring out unknown algorithms, investing quite a lot of money to pay someone else to develop code I didn't understand, finding the items for a portable high-speed computer involving the "blind" 68000 CPU with the Sharp as a terminal and the printer for the convenient output, and then actually emptying the machines myself, was one of the most exciting things I ever did with my programming skills.
Way back in the early 90s, I forgot my Compuserve password. I had the encrypted version in CIS.INI, so I wrote a small program to do a plaintext attack and analysis in an attempt to reverse-engineer the encryption algorithm. 24 hours later, I figured out how it worked and what my password was.
Soon after that, I did a clean-up and published the program as freeware so that Compuserve customers could recover their lost passwords. The company's support staff would frequently refer these people to my program.
It eventually found its way onto a few bulletin boards (remember them?) and Internet forums, and was included in a German book about Compuserve. It's still floating around out there somewhere. In fact, Google takes me straight to it.
Once, when playing Daggerfall II, I could not afford the Daedric Dai-Katana so I hex-edited the savegame.
Being serious though, I managed to remove the dongle check on my dads AutoCAD installation using SoftICE many years ago. This was before the Internet was big. He works as an engineer so he had a legitimate copy. He had just forgotten the dongle at his job and he needed to do some things and I thought it would be a fun challenge. I was very proud afterwards.
Okay, this wasn't reverse engineering (quite) but a simple hardware hack born of pure frustration. I was an IT manager for a region of Southwestern Bell's cell phone service in the early 90s. My IT department was dramatically underfunded and so we spent money on smart people rather than equipment.
We had a WAN between major cities, used exclusively for customer service, with critical IP links. Our corporate bosses were insistent that we install a network monitoring system to notify us when the lines went down (no money for redundancy, but spend bucks for handling failures. Sigh.)
The STRONGLY recommended solution ran on a SPARC workstation and started at $30K plus the cost of a SPARC station (around $20K then), together which was a substantial chunk of my budget. I couldn't see it - this was a waste of $$. So I decided a little hacking was in order.
I took an old PC scheduled for destruction and put a copy of ProComm (remember ProComm?) and had it ping each of the required nodes along the route (this was one of the later versions of ProComm that scripted FTP as well as serial lines, KERMIT, etc.) A little logic in the coding fired-off a pager message when a node couldn't be reached. I had already used it to cobble together a pager system for our techs, so I reused the pager code. The script ran continuously, sending a ping once each minute across each of the critical links, and branched into the pager code when a ping wasn't returned.
We duplicated this system at each critical location for a cost of less than $500 and had a very fast notification when a link went down. Next issue - one of our first trouble-shooting methods was to power-cycle our routers and/or terminal servers. I got some dial-up X10 controllers and a few X10 on/off appliance power switches. You had to know the correct phone number to use and the correct tones to push, but we printed up a cheat card for each technician and they kept it with their pager. Instant fast response! One of my techs then programmed the phones we all had to reset specific equipment at each site as a speed-dial. One-tech solves the problem!
Now the "told-you-so" unveiling.
I'm sitting at lunch with our corporate network manager in Dallas who is insisting on a purchase of the Sun-based network management product. I get a page that one of our links is down, and then a second page. Since the pager messages are coming from two different servers, I know exactly which router is involved (it was a set-up, I knew anyway, as the tech at the meeting with me was queued to "down a router" during the meal so we could show-off.) I show the pager messages to the manager and ask him what he would do to resolve this problem. He eyes me suspiciously, since he hasn't yet successfully been paged by his Solaris NMS system that is supposed to track critical links. "Well, I guess you'd better call a tech and get them to reset the router and see if that fixes it." I turned to the tech who was lunching with us and asked him to handle it. He drew out his cell phone (above the table this time) and pressed the speed-dial he had programmed to reset the router in question. The phone dialed the X10 switch, told it to power-off the router, paused for five seconds, told it to power-up the router, and disconnected. Our ProComm script sent us pages telling us the link was back up within three minutes of this routine. :-)
The corporate network manager was very impressed. He asked me what the cost was for my new system. When I told him less than $1K, he was apoplectic. He had just ordered a BIG set of the Sun Solaris network management solution just for the tasks I'd illustrated. I think he had spent something like $150K. I told him how the magic was done and offered him the ProComm script for the price of lunch. TANSTAAFL. He told me he'd buy me lunch to keep my mouth shut.
Cleaning out my old drawers of disks and such, I found a copy of the code - "Pingasaurus Rex" was the name I had given it. That was hacking in the good old days.
The most painful for me was for this product where we wanted to include an image on a Excel Spreadsheet (few years back before the open standards). So I had to get and "understanding" if such thing exists of the internal format for the docs, as well. I ended up doing some Hex comparison between files with and without the image to figure out how to put it there, plus working on some little endian math....
I once worked on a tool that would gather inventory information from a PC as it logged into the network. The idea was to keep track of all the PCs in your company.
We had a new requirement to support the Banyan VINES network system, now long forgotten but pretty cool at the time it came out. I couldn't figure out how to get the Ethernet MAC address from Banyan's adapter as there was no documented API to do this.
Digging around online, I found a program that some other Banyan nerd had posted that performed this exact action. (I think it would store the MAC address in an environment variable so you could use it in a script). I tried writing to the author to find out how his program worked, but he either didn't want to tell me or wanted some ridiculous amount of money for the information (I don't recall).
So I simply fired up a disassembler and took his utility apart. It turned out he was making one simple call to the server, which was an undocumented function code in the Banyan API. I worked out the details of the call pretty easily, it was basically asking the server for this workstations address via RPC, and the MAC was part of the Banyan network address.
I then simply emailed the engineers at Banyan and told them what I needed to do. "Hey, it appears that RPC function number 528 (or whatever) returns what I need. Is that safe to call?"
The Banyan engineers were very cool, they verified that the function I had found was correct and was pretty unlikely to go away. I wrote my own fresh code to call it and I was off and running.
Years later I used basically the same technique to reverse engineer an undocumented compression scheme on an otherwise documented file format. I found a little-known support tool provided by the (now defunct) company which would decompress these files, and reverse engineered it. It turned out to be a very straightforward Lempel-Ziv variant applied within the block structure of their file format. The results of that work are recorded for posterity in the Wireshark source code, just search for my name.
Almost 10 years ago, I picked up the UFO/XCOM Collector's Edition in the bargain bin at a local bookstore, mostly out of nostalgia. When I got back home, I got kinda excited that it had been ported to Windows (the DOS versions didn't run under win2k)... and then disappointed that it had garbled graphics.
I was about to shrug my shoulders (bargain bin and all), but then my friend said "Haven't you... bugfixed... software before?", which led to a night of drinking lots of cola and reverse-engineering while hanging out with my friend. In the end, I had written a bugfix loader that fixed the pitch vs. width issue, and could finally play the two first XCOM games without booting old hardware (DOSBOX wasn't around yet, and my machine wasn't really powerful enough for fullblown virtualization).
The loader gained some popularity, and was even distributed with the STEAM re-release of the games for a while - I think they've switched to dosbox nowadays, though.
I wrote a driver for the Atari ST that supported Wacom tablets. Some of the Wacom information could be found on their web sites, but I still had to figure out a lot on my own.
Then, once I had written a library to access the wacom tables (and a test application to show the results) - it dawned on me that there was no API for the OS (GEM windowing system) to actually place the mouse cursor somewhere. I ended up having to hook some interrupts in something called the VDI (like GDI in windows), and be very very careful not to crash the computer inside there. I had some help (in the form of suggestions) from the developers of an accelerated version of the VDI (NVDI), and everything was written in PurePascal. I still occasionally have people asking me how to move the mouse cursor in GEM, etc.
I've had to reverse engineer a video-processing app, where I only had part of the source code. It took me weeks and weeks to even work out the control-flow, as it kept using CORBA to call itself, or be called from CORBA in some part of the app that I couldn't access.
Sheer idiocy.
I recently wrote an app that download the whole content from a Domino Webmail server using Curl. This is because the subcontractor running the server asks for a few hundred bucks for every archive request.
They changed their webmail version about one week after I released the app for the departement but managed to make it working again using a GREAT deal of regex and XML
When I was in highschool they introduced special hours each week (there were 3 hours if i recall correctly) in which we had to pick a classroom with a teacher there to help with any questions on their subject. No of course everybody always wanted to spend their time in the computer room to play around on the computers there.
To choose the room where you would have to be there was an application that would monitor how many students would go to a certain room, and so you had to reserve your slot on time or otherwise there was not much choice where to go.
At that time I always liked to play around on the computers there and I had obtained administrator access already, only for this application that would not help me so much. So I used my administrator access to make a copy of the application and take it home to examine. Now I don't remember all the details but I discoverd this application used some access database file located on a hidden network share. Then after taking a copy of this database file I found there was a password on the database. Using some linux access database tools I could easily work around that and after that it was easy to import this database in my own mysql server.
Then though a simple web interface I could find details for every student in the school to change their slots and promote myself to sit in my room of choice every time.
The next step was to write my own application that would allow me to just select a student from the list and change anything without having to look up their password which was implemented in only a few hours.
While not such a very impressive story as some others in this thread, I still remember it was a lot of fun to do for a highschool child back then.
A friend of mine brought up this questiont he other day, he's recently bought a garmin heart rate moniter device which keeps track of his heart rate and allows him to upload his heart rate stats for a day to his computer.
The only problem is there are no linux drivers for the garmin USB device, he's managed to interpret some of the data, such as the model number and his user details and has identified that there are some binary datatables essentially which we assume represent a series of recordings of his heart rate and the time the recording was taken.
Where does one start when reverse engineering data when you know nothing about the structure?
I had the same problem and initially found this project at Google Code that aims to complete a cross-platform version of tools for the Garmin devices ... see: http://code.google.com/p/garmintools/. There's a link on the front page of that project to the protocols you need, which Garmin was thoughtful enough to release publically.
And here's a direct link to the Garmin I/O specification: http://www.garmin.com/support/pdf/IOSDK.zip
I'd start looking at the data in a hexadecimal editor, hopefully a good one which knows the most common encodings (ASCII, Unicode, etc.) and then try to make sense of it out of the data you know it has stored.
As another poster mentioned, reverse engineering can be hairy, not in practice but in legality.
That being said, you may be able to find everything related to your root question at hand by checking out this project and its' code...and they do handle the runner's heart rate/GPS combo data as well
http://www.gpsbabel.org/
I'd suggest you start with checking the legality of reverse engineering in your country of origin. Most countries have very strict laws about what is allowed and what isn't regarding reverse engineering devices and code.
I would start by seeing what data is being sent by the device, then consider how such data could be represented and packed.
I would first capture many samples, and see if any pattern presents itself, since heart beat is something which is regular and that would suggest it is measurement related to the heart itself. I would also look for bit fields which are monotonically increasing, as that would suggest some sort of time stamp.
Having formed a hypothesis for what is where, I would write a program to test it and graph the results and see if it makes sense. If it does but not quite, then closer inspection would probably reveal you need some scaling factors here or there. It is also entirely possible I need to process the data first before it looks anything like what their program is showing, i.e. might need to integrate the data points. If I get garbage, then it is back to the drawing board :-)
I would also check the manufacturer's website, or maybe run strings on their binaries. Finding someone who works in the field of biomedical engineering would also be on my list, as they would probably know what protocols are typically used, if any. I would also look for these protocols and see if any could be applied to the data I am seeing.
I'd start by creating a hex dump of the data. Figure it's probably blocked in some power-of-two-sized chunks. Start looking for repeating patterns. Think about what kind of data they're probably sending. Either they're recording each heart beat individually, or they're recording whatever the sensor is sending at fixed intervals. If it's individual beats, then there's going to be a time delta (since the last beat), a duration, and a max or avg strength of some sort. If it's fixed intervals, then it'll probably be a simple vector of readings. There'll probably be a preamble of some sort, with a start timestamp and the sampling rate. You can try decoding the timestamp yourself, or you might try simply feeding it to ctime() and see if they're using standard absolute time format.
Keep in mind that lots of cheap A/D converters only produce 12-bit outputs, so your readings are unlikely to be larger than 16 bits (and the high-order 4 bits may be used for flags). I'd recommend resetting the device so that it's "blank", dumping and storing the contents, then take a set of readings, record the results (whatever the device normally reports), then dump the contents again and try to correlate the recorded results with whatever data appeared after the "blank" dump.
Unsure if this is what you're looking for but Garmin has created an API that runs with your browser. It seems OSX is supported, as well as Windows browsers... I would try it from Google Chromium to see if it can be used instead of this reverse engineering...
http://developer.garmin.com/web-device/garmin-communicator-plugin/
API Features
Auto-detection of devices connected to a computer Access to device
product information like product name and software version Read
tracks, routes and waypoints from supported recreational, fitness and
navigation devices Write tracks, routes and waypoints to supported
recreational, fitness and navigation devices Read fitness data from
supported fitness devices Geo-code address and save to a device as a
waypoint or favorite Read and write Garmin XML files (GPX and TCX) as
well as binary files. Support for most Garmin devices (USB, USB
mass-storage, most serial devices) Support for Internet Explorer,
Firefox and Chrome on Microsoft Windows. Support for Safari, Firefox
and Chrome on Mac OS X.
Can you synthesize a heart beat using something like a computer speaker? (I have no idea how such devices actually work). Watch how the binary results change based on different inputs.
Ripping apart the device and checking out what's inside would probably help too.