I am using a IDTech Shuttle to swipe card data in my iOS app and I need to send Track1 and Track2 as separate values to my card processor. I have researched getting track1 and track2 data and it looks pretty straight forward except my returned swipe data does not follow the same format as described my all of the posts I have read.
My swipe data looks something like this:
J(LbÐðhQRÍm©½gÝD|}xÆÁ°ø)Cc+%N9;Aq6*ØÉ\ØsÀüÝXþYü;tHÎMHãøÃH¡æ´v¤æe£õ®;PJá#÷{oö zú5OËáÒðìåÍ.;°¿äT125007331bI$A
Æ
How do I parse that into 2 separate tracks? I am assuming there is some sort of format here
IDTECH encrypted devices (ED), Shuttle included, are HEX output and HID. You will need to acquire the SDK for the Shuttle specifically as there are 2 output formats for IDTECH ED's and I think the Shuttle uses the newer of the 2.
You can then build a parser which will count the field lengths, some are are just 2 (I believe the first 6 to 8 are) and some are variable with padding to conform to a fixed length.
I believe you can there are 3 fields, track 1 and 2, track 1 and track 2, you would be interested in.
Related
I'm collecting measurements with a Telegraf client. Unfortunately, the measurement name isn't static. Rather, it encodes a timestamp (terrible design choice, but out of my hands) as part of its name.
For example, the following 3 lines represent 3 instances of the same measurement, but have different names:
info.quorum.2902864.agree: 6
info.quorum.2902865.agree: 6
info.quorum.2902866.agree: 5
...
is there a way to transform these measurement names into one static name? In other words, I'd like to transform these entries above to:
info.quorum.hello.agree: 6
info.quorum.hello.agree: 6
info.quorum.hello.agree: 5
I saw the rename processor (https://github.com/influxdata/telegraf/tree/master/plugins/processors/rename) - but that doesn't support wildcard.
I also saw the regex processor (https://github.com/influxdata/telegraf/tree/master/plugins/processors/regex) but that doesn't support measurement names.
any ideas on how to get this done?
EDIT: some background: the measurements are collected with http input, usin a GJSON path like a.b.*.c
EDIT2: here's what i'm trying to parse. the problem is with the key '2931747', which grows on each subsequent reading:
"quorum" : {
"2931747" : {
"agree" : 8,
"disagree" : 0,
}
So they put actual value there as the key... Downright, eh, unsmart, let's put it this way.
And I won't blame the writers of JSON format parser for not putting a handle for that situation.
So, the answer is: in current form, with HTTP plugin, available parsers & processors - there's no way to shape it in any proper form (unless you can drop that damned number-key completely - then it's trivial).
I would suggest you to push on data providers to make them stop this stupidity.
If that is not an option - you need to write your own processor for that, alas.
It could be either fully standalone (poll the http endpoint, parse the stuff, form a batch of line protocol records, send to influx) - or it could cut it off on producing lines in Influx line protocol as the its output, and be executed with Exec input plugin
I am currently using Swift to store some data on iOS. The values come as a 2-D integer array, defined as an [[Int]]. I need to save these integer arrays to disk. Currently, I am using the following function to do so:
func writeDataToFile(data: [[Int]], filename: String){
let fullfile = NSString(string: self.folderpath).stringByAppendingPathComponent(filename+".txt")
var fh = NSFileHandle(forWritingAtPath: fullfile)
if fh == nil{
NSFileManager.defaultManager().createFileAtPath(fullfile, contents: nil, attributes: nil)
fh = NSFileHandle(forWritingAtPath: fullfile)
}
fh?.writeData("Time: \(filename)\n".dataUsingEncoding(NSUTF16StringEncoding)!)
fh?.writeData("\(data)".dataUsingEncoding(NSUTF16StringEncoding)!)
fh?.closeFile()
}
Currently this function works just fine, but it produces files that are relatively large (1.1mb each - which when you are writing them at 1 Hz, gets huge fast). The arrays written have a fixed size and the values will be from 20000 < x < 35000. Is there a way to compress this data on the fly such that I can later read the data into say Python or some other language? Would it just be easier to use some library like Zip to compress the files into zips after writing? Is there some way to transform the data (without loss of data/fidelity) into an image (for compression purposes, not viewing purposes). There is some metadata that I would like to store along with the 2-D array, such as a timestamp.
Since you are currently saving those as string values, the simplest and fastest size reduction would be to save them as binary values (or base64 encoded strings). Then you could convert all of your int values into 2 byte sets (since unsigned 2 bytes can store up to 65536) and save the values that way. That would go from 5 bytes per int value down to 2 bytes per int value. Immediate savings of 60%.
For the Base64 encoding I use something I found on the internet called NSData+Base64. But in looking that up I just read:
In the iOS 7 and Mac OS 10.9 SDKs, Apple introduced new base64 methods on NSData that make it unnecessary to use a 3rd party base 64 decoding library. What's more, they exposed access to private base64 methods that are retrospectively available back as far as IOS 4 and Mac OS 6.
Link.
You could go much further into the compression by realizing that data from one element to the next will likely not change by the entire range, since heat maps will always be gradients. Then you could save the arrays as difference since the last element and likely get that down to a single byte (255 value) change set. But that may lose precision if you are viewing something with a very fast heat gradient (or using a low resolution camera).
If you eventually need to get into compression, I use GTMNSData+zlib and decompress it in a c# webservice. So with a little bit of work it is cross platform.
A proper answer for this would require more information about the problem domain. Most likely, 2D arrays are the wrong data structure for this but it's hard to tell without more info.
What's the data stored in these arrays?
Apple has had a compression library since last year:
https://developer.apple.com/library/ios/documentation/Performance/Reference/Compression/index.html
We have an application that prints 2 invoice copies - 1 on white (for the cust) and 1 on blue (for us).
We print a LOT of these so we are getting a printer with 3 big trays. One tray (tray 5) holds 4000 sheets and the other two (trays 3 and 4) are a tandem set holding 1600 and 2000 sheets. The application automatically generates the invoice and sends one document to the tray with the white paper and one to the tray with the blue paper.
The user has no input in this process.
Now, my problem is this - if I specifically send the blue copy to tray 3 and there is no paper in tray 3, the job will go on hold until someone loads it up even though tray 4 has 2000 more sheets ready to go. On the other hand, if I tell the printer to print on Blue 8 1/2x11" paper, it is smart enough to know that that type of paper is in both trays and to pull from either one until they are both empty. So, I want to change our application to select a paper type/size and color instead of a specific tray.
The program is written in Delphi and I have been looking at the DEVMODE structure returned by TPrinter.GetPrinter. The DEVMODE structure has a memory size in dmDriverExtra that indicates how much extra data the print driver is adding to the structure for its own storage.
Does anyone know of anyway to access this data and make changes to it? If you have examples in other languages, I can probably adapt it to Delphi so anything will help.
There are actually two different items in the questions:
How to set the pater size and type:
PaperSize would be stored in dmPaperSize (value DMPAPER_LETTER)
PaperType is a bit more difficult. I'd guess that it's in dmMediaType (use DeviceCapabilities to retrieve available media types and their names)
How to access / edit "DriverExtra" data:
In short: don't!
A bit longer: dmDriverExtra is described as "Contains the number of bytes of private driver-data that follow this structure". So this data is private to the driver (which means that you need very good documentation for the driver to actually know the format and content of this data. It's not guaranteed that different versions of the driver use the same format).
So the only thing you can do is to use a print dialog, retrieve the DevMode structure and store it for further use (however as I said: If the driver changes, this data may become invalid...)
I have a table with columns as LowerFrequency, HigherFrequency and ID. The frequencies entered have a suffix of khz or mhz. I want to search a specific frequency by checking the range it falls in i.e between the lower and higher frequencies and fetch the respective ID.
The query I implemented was as below but it returns a wrong output:
select tablename.ID where "100 khz" between tablename.LowerFrequency and tablename.HigherFrequency;
I know the reason is because of the khz that follows the integer. But I need some suggestions to handle this as I am not in a situation of changing the whole DB file because it is time consuming.
I will be integrating this DB with my iPhone app. So any solutions in Objective C would also be appreciated. I mean some kind of conversion.
I'm trying to develop an iPhone app that will use the camera to record only the last few minutes/seconds.
For example, you record some movie for 5 minutes click "save", and only the last 30s will be saved. I don't want to actually record five minutes and then chop last 30s (this wont work for me). This idea is called "Loop recording".
This results in an endless video recording, but you remember only last part.
Precorder app do what I want to do. (I want use this feature in other context)
I think this should be easily simulated with a Circular buffer.
I started a project with AVFoundation. It would be awesome if I could somehow redirect video data to a circular buffer (which I will implement). I found information only on how to write it to a file.
I know I can chop video into intervals and save them, but saving it and restarting camera to record another part will take time and it is possible to lose some important moments in the movie.
Any clues how to redirect data from camera would be appreciated.
Important! As of iOS 8 you can use VTCompressionSession and have direct access to the NAL units instead of having to dig through the container.
Well luckily you can do this and I'll tell you how, but you're going to have to get your hands dirty with either the MP4 or MOV container. A helpful resource for this (though, more MOV-specific) is Apple's Quicktime File Format Introduction manual
http://developer.apple.com/library/mac/#documentation/QuickTime/QTFF/QTFFPreface/qtffPreface.html#//apple_ref/doc/uid/TP40000939-CH202-TPXREF101
First thing's first, you're not going to be able to start your saved movie from an arbitrary point 30 seconds before the end of the recording, you'll have to use some I-Frame at approximately 30 seconds. Depending on what your Keyframe Interval is, it may be several seconds before or after that 30 second mark. You could use all I-frames and start from an arbitrary point, but then you'll probably want to re-encode the video afterward because it will be quite large.
SO knowing that, let's move on.
First step is when you set up your AVAssetWriter, you will want to set its AVAssetWriterInput's expectsMediaDataInRealTime property to YES.
In the captureOutput callback you'll be able to do an fread from the file you are writing to. The first fread will get you a little bit of MP4/MOV (whatever format you're using) header (i.e. 'ftyp' atom, 'wide' atom, and the beginning of the 'mdat' atom). You want what's inside the 'mdat' section. So the offset you'll start saving data from will be 36 or so.
Each read will get you 0 or more AVC NAL Units. You can find a listing of NAL unit types from ISO/IEC 14496-10 Table 7-1. They will be in a slightly different format than specified in Annex B, but it's fine. Additionally, there will only be IDR slices and non-IDR slices in the MP4/MOV file. IDR will be the I-Frame you're looking to hang onto.
The NAL unit format in the MP4/MOV container is as follows:
4 bytes - Size
[Size] bytes - NALU Data
data[0] & 0x1F - NALU Type
So now you have the data you're looking for. When you go to save this file, you'll have to update the MPV/MOV container with the correct length, sample count, you'll have to update the 'stsz' atom with the correct sizes for each sample and things like updating the media headers and track headers with the correct duration of the movie and so on. What I would probably recommend doing is creating a sample container on first run that you can more or less just overwrite/augment with the appropriate data for that particular movie. You'll want to do this because the encoders on the various iDevices don't all have the same settings and the 'avcC' atom contains encoder information.
You don't really need to know much about the AVC stream in this case, so you'll probably want to concentrate your experimenting around updating the container format you choose correctly. Good luck.