I've noticed that raw data from my webcam comes in the from of YUY2. Actually, this "raw data" is the input for an AVICAP callback, and I suppose that this is the actual data from the webcam.
Anyway, do all the webcams use YUY2 format, or should I expect different formats as well?
YUY2/YUYV are probably most common. I've also seen web cams that used MJPEG, but are less common. Covering both of those will deal with a majority of non-network (Java or otherwise) style web cams.
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I'm interested in playing with AI/ML tools and was wondering if this is a good problem to solve with that kind of tool? It would also be pretty useful in my day job if it actually worked.
The idea is if you have a bunch of messages of unknown origin that are binary data, would some form of pattern-recognition be able to determine that the message was encoded using a particular encoding tool like protobuf/capnproto/avro/etc.?
I know this sounds a little bizarre, but there is a very simple application I want to write, a sort of unique image viewer, which requires some interactivity with the host system at the user level. Simplicity when developing is a must as this is a very small side project. The project does require some amount of graphical work and quite a bit of mouse based interactivity (as well as some keyboard shortcuts), but quite frankly, I don't want to dig my hands into OGL for something this small. I looked at the available options, and I think I've narrowed it down to two main choices: Webkit (through either QtWebkit or WebkitGtk), and the language Processing.
Since I haven't actually used Processing but I do have some amount of HTML5 canvas and Javascript experience, I am somewhat tempted to using a Webkit based solution. There are however, several concerns I have.
How is Webkit's support for canvas, specifically for more graphically intensive processes?
I've heard that bridging is handled better in QtWebkit than WebkitGtk. Is this still true?
To what degree can bridging actually do? Can a Webkit based application do everything that an application which interacts with the files on the system needs?
Looking at Processing, there are similarly, a couple things I'm wondering.
Processing is known for its graphical capabilities, but how capable is it for writing a general everyday desktop application?
There are many sources that link Processing to Java, both in lineage as well as in distributing applications over the web (ie: JApplets). Is the "Application Export" similarly closely integrated with Java?
As for directly comparing the two, the main concern I do have is the overhead of each. I want the application to start up as snappy as possible, and I know that Java has a bit of an overhead regarding start up because it first has to start up the interpreter. How do Processing and QtWebkit/WebkitGtk compare for start up?
Note that I am targeting the Linux platform only.
Thanks!
It's difficult to give a specific answer, because you're actually asking a few different kind of questions - and some of them you could be more precise.
Processing is a subset or child of java - it's really "just" a java framework with an free ide that hides the messy setup work of building an applet, so that a user can dive in and write something quickly without getting bogged down in widgets and ui, etc. So processing can exist by itself and the end user needs to know nothing of Java (except syntax - processing is java, so the user must learn java syntax).
But a programmer who already knows java can exploit the fun quick nature of processing and then leverage their normal java experience for whatever else is needed - everything of java is in processing, just a maybe slightly hidden (but only at first) It's also possible to import the processing.jars into an existing java program and use them there. See http://processing.org/learning/eclipse/ form more information.
"how capable is it for writing a general everyday desktop application?" - Not particularly on it's own (it's not made to be), but some things are possible and easy (i.e. file saving & loading, non-standard gui, etc.), and in some ways it's similar to old school actionscript or lingo. There is a library called controlP5 that makes gui stuff a bit easier.
Webkit is another kettle of fish, especially if you aren't making a web-based thing (it sounds like you're thinking on using the webkit libraries as part of a larger program. I'll admit I don't have the dev expertise with those specific libraries to give you the answer you really want, but I'm pretty certain that unless you have programming experience beyond html5/javascript you'll probably get going much faster with processing.
Good luck with whichever path you choose!
I need to write a logic engine for an application. Essentially, this thing is going to be fed a bunch of data in an XML file, and it then crunches that data and produces an XML file as its result.
The trick is that this engine will need to run on a server (probably Windows, and probably as a background service) AND it will need to on mobile devices - iOS and Android, primarily.
The logic isn't that awfully difficult or complex. On the mobile devices, the idea is to give researchers quick-and-dirty access to the engine for very tiny data sets. The server "version" will do exactly the same work, but do it on huge data sets.
The GUI will be abstracted from this logic engine.
I should point out that the "mobile version" should be able to work offline - meaning that whatever I choose to implement this logic engine in, it needs to run natively on the devices. THAT said, it's perfectly fine for it to run in the mobile device's local Web browser in a locally-stored file. For example, I'd originally considered JavaScript for this - except I don't think there's a way to have JavaScript running in a multi-threaded service on the server side of things.
Is there a single language that offers to do this? With a minimum of re-coding between platforms?
You can use Rhino to execute JavaScript from inside a Java server/servlet. I'm not sure how parallel/threaded the engine is. You can also look into hosting Google V8, which probably will be higher performance/more scalable.
I don't think you can do all of this (you probably can, but it wouldn't be very pretty) in one language.
Java (or another JVM language like Scala, Clojure or Groovy) is the closest you can do: it's the single platform that allows compiled code to be run unchanged on the largest range of platforms.
However I'm not sure how good Java support is on iOS - this might be the tricky one. But this is going to be a problem in any case: Apple don't seem particularly keen on encouraging anything other than their own tools.
Perhaps the best strategy is to write in Java (which will cover your servers and 95% of your client platforms) and then have a small client side portion that you can quickly port for special cases like iOS.
This spec http://www.w3.org/TR/webdatabase/ says:
This document was on the W3C Recommendation track but specification work has stopped. The specification reached an impasse: all interested implementors have used the same SQL backend (Sqlite), but we need multiple independent implementations to proceed along a standardisation path.
Does this mean that HTML5 database is going away, and for some time we will have a de-facto standard using SQLite, possibly with browser differences? Or has the W3C published a plan of attack for finishing the standard?
According to this article:
[...] we think it is worth explaining our design choices, and why we think IndexedDB is a better solution for the web than Web SQL Database.
In another article, we compare IndexedDB with Web SQL Database, and note that the former provides much syntactic simplicity over the latter. IndexedDB leaves room for a third-party JavaScript library to straddle the underlying primitives with a BTree API, and we look forward to seeing initiatives like BrowserCouch built on top of IndexedDB. Intrepid web developers can even build a SQL API on top of IndexedDB. We’d particularly welcome an implementation of the Web SQL Database API on top of IndexedDB, since we think that this is technically feasible. Starting with a SQL-based API for use with browser primitives wasn’t the right first step, but certainly there’s room for SQL-based APIs on top of IndexedDB.
I'm not personally swayed by the arguments put forth in the article, but it seems clear that (for the time being) Mozilla has decided that Web SQL Database is dead.
Further interesting comments about this article may be found on Hacker News.
My understanding is that this is now called "IndexedDB"
http://www.w3.org/TR/IndexedDB/
Apparently the Firefox team has started implementing this:
http://hacks.mozilla.org/2011/01/indexeddb-in-firefox-4/
I don't know if anyone knows the answer. Mozilla doesn't like the dependence upon SQLite and has decided to go a different way. However, all WebKit based browsers already have it implemented and I don't see them removing it as any websites built to take advantage of the spec would be broken.
This means that at least in certain contexts, mostly within the mobile sphere where most browsers have a webkit implementation, it can still makes sense to use the HTML5 Web SQL spec. I see this as especially true for developers who are looking to create mobile applications using a framework like phonegap.
There are some times where as an application developer you want to provide users with access to data even if they aren't connected to the internet or if the connection is slow and some types of data is just more efficiently stored in a database than in a cookie or JSON cashe. For example, if you have data that has relationships it is much easier and quicker to do a join query to pull the data you need than it is to search a json map.
I don't think the spec is dead, and I actually hope that Mozilla will reverse their stance so that developers can use it to solve problems outside of the mobile webkit world.
I have a requirement to write a web service that allows me to post an image to a server along with some additional information about that image.
I'm completely new to developing web services (normally client side dev) so I'm a little stumped as to what I need to look into and try.
How do you post binary data and plain text into a servic?
What RequestFormat should I use?
It looks like my options are xml or json. Can I use either of these?
Bit of a waffly question but I just need some direction rather than a solution as I can't seem to find much online.
After reading this guide to building restuful services I figured I was going about the problem the wrong way. The image and text are actually two seperate resources and so should probably be handled seperately. I now have a service that uploads an image and returns a uri to that image and a seperate service to post textual data relating to that image along with the uri to that image.
Though I don't have experience with WCF, I can tell you a painless way to handle POSTing/PUTting of binary data in a REST API (especially one with a mix of text + binary) is to encode the binary data as base64 and treat it much like any other text data in your API.
Yes, there is a slight overhead with base64 in terms of size and an additional encode/decode process, however, base64 is typically only 1.37x larger than binary.
I find in many cases the overhead is well worth avoiding the pain that can be involved with binary data in APIs, especially when you need to POST/PUT a combination of binary and text data. If you wanted to POST an image and additional meta/text data you could easily do so with a json string ("image" would be your base64 encoded image)...
{
"image":"aGVsbG8...gd29ybGQ=",
"user" : 1234,
"sub_title": "A picture from my trip to Pittsburgh"
}
This is by no means the best solution for all cases, and as I said, I'm not a WCF expert, but it's certainly something to consider in the general case to make your life easier.
If you are using WebServiceHost in WCF 3.5 then you need to read this. If you have to use WCF to do HTTP based stuff then try and get onto .Net 4. I believe they have made a whole lot of things much easier.
If you are stuck with 3.5, welcome to a world of pain. Find everything you can written by Aaron Skonnard on the subject. And as I suggested in the comments of the other question, learn how to use SvcTrace.