Need to know if it is possible to mix several rtmp threads into one using modules? By Picture-in-Picture type, or simply there is a main stream, and additional streams add sound. It's the mixing that I need so that all the streamers can be heard at the same time.
I need to see if that's possible in principle, so I don't have to spend time on investigating if that's not possible. And what skills does a specialist need to have in order to create a module like this?
Wowza Streaming Engine does not support compositing today (4.8.5), so I would recommend merging the streamings prior to ingesting them as a single source.
Related
Can we combine OpenMP and MapReduce something like this:
Map/Reduce can be used to distribute the data set among different computers.
Then each computer runs mapper/reducer function that take advantage of multiprocessing
using OpenMP.
Is this possible? (I couldn't find anything substantial on google search).
If this possible, would there be any advantage of this?
P.S. I'm using Hadoop Streaming Utility.
The point of Hadoop is to have processing nodes deal with data locality automatically and transparently for you.
If I understand your correctly you want to use Hadoop just for storage, and then do your Map/Reduce work in OpenMP. While this should be possible, you will end up losing one of the main design advantages of Hadoop.
This approach does not make a lot of sense. I suggest either sticking to the Hadoop framework, or looking at one of the alternatives if you don't like it.
I am currently looking for a discrete event simulator written for C++. I did not find much on the web written specifically in OO-style; there are some, but outdated. Some others, such as Opnet, Omnet and ns3 are way too complicated for what I need to do. And besides, I need to simulate agent-based algorithms capable of simulating systems of thousands of nodes.
Does anybody know anything suitable for my needs?
Others have good direct answers, but I'm going to suggest an alternative. If I understand you right, you want a system in C++ or such where you can post events that fire in the future, and code is run when those events fire.
I had a project to do like this, and I started out trying to write such an event system in C++ and then quickly realized I had a better solution.
Have you considered writing your program in behavioral Verilog? That may seem strange to write software in a hardware description language, but a Verilog simulator is an event-based system underneath, and behavioral Verilog is a very convenient way to express events, timing, triggers, etc. There is a free Verilog simulator (which is what I used) called Icarus Verilog. If you're not using Ubuntu or some Linux distro with Icarus already in a package, building from source is straightforward.
I would recommend having a second look to OmNet++. At first sight it may look quite complex, but if you look it into more detail you will find that most of the complexity is in the network add-on (the INET Framework). Unless you are going to do a detailed network simulation you do not need the INET.
Using OmNet++ core is not specially difficult and it may be simpler than other similar tools.
You may want to have a look to an intro.
One of the things that makes OmNet++ attractive to me is its scalability. Is possible to run large simulations in a desktop. Besides, it is possible to scale the same simulation to a cluster without rewriting the code.
You should consider SystemC, although I'd also recommend taking a second look at OmNet++.
We use SIMLIB at my school. It is very fast, easy to understand, object oriented, discrete and continuous simulator. It might look outdated but it is still maintained.
There is CSIM from Mesquite Software which supports developing models in C, C++ and Java. However, it is paid-commercial, AFAIK.
Take a look at GBL library. It's written in modern C++ and even supports C++0x features like move semantics and lambda functions. It offers several modeling mechanisms: synchronous and asynchronous event handlers, preemptive threads, and fibers. You can create purely behavioral, cycle accurate, and real-time models, or any mixture of those.
I'm running a PHP front end to an application that does a lot of work with data and uses Cassandra as a data store.
However I know PHP will not give me the performance I need for some of the calculations (as well as the management for the sheer amount of data that needs to be in memory)
I'd like to write the backed stuff in C++ and access it from the PHP application. I'm trying to figure out the best way to interface the two.
Some options I've looked at:
Thrift (A natural choice since I'm already using it for Cassandra)
Google's Protocol Buffers
gSOAP
Apache Axis
The above are only things I looked at, I'm not limiting myself.
The data being transferred to the PHP application is very small, so streaming is not required. Only results of calculations are transferred.
What do you guys think?
If I were you I'd use thrift, no sense pulling in another RPC framework. Go with what you have and already know. Thrift makes it so easy (so does google protocol buffers, but you don't really need two different mechanisms)
Are you limiting yourself to having C++ as a separate application? Have you considered interfacing it with the PHP directly? (i.e. link a C++ extension into your PHP application).
I'm not saying the second approach is necessarily better than the first, but you should consider it anyway, because it offers some different tradeoff choices. For example, the latency of passing stuff between the PHP and C++ would surely be higher when the two are separate applications than when they're the same application dynamically linked.
More details about how much data your computations will need would be useful. Thrift does seem like a reasonable choice. You could use it between PHP, your computation node, and the Cassandra backend. If your result is small, your RPC transport between PHP and the computation node won't make too much difference.
I am attempting to use the pipe interface to gnuplot (a standard one gnuplot_i.{cpp,hpp}) in order to generate a real time display of values that are continually changing within another program written in C++. This works ok but I wanted to see if anyone had any suggestions for improvement.
This implementation contains a convenience method to plot a single vector and 2 vectors as a 2D plot. It achieved this by writing out to a temporary file via a standard library call to the mktemp function and then using that as input to a gnuplot plot call. This generated too many temporary files and didn't appear to work well when the update rate on the plot is high (maybe IO limited at a point). I have decided to use the '-' pseudo file in the plot call and just send the vectors directly to the pipe (ended with a single line with "e" on it). This works better but is still not great.
Is there a slicker way to do what I am attempting to do than to continually regenerate the plot when the values have changed? How often is it safe to update the plot with new information? Alternatively, maybe there's a much simpler way to achieve what I am trying to do?
#Andy Ross
I have no "requirements" per se. What I meant by slick was that maybe there was a more elegant approach to doing what I was attempting while still using gnuplot. Although elegant is subjective, I find the approach I am presently taking particularly inelegant. What I meant by safe was whether anyone knew at what update rate there would be IO problems (e.g., latency, lock-up of display, etc.) with said approach.
I'd like to avoid using a toolkit for the following reasons (my short-list at least).
I have found that they are generally nontrivial to install properly on different architectures especially as non-root (and when they require dependencies that aren't standard across OSes).
They incur an additional compilation dependency for other people using this software.
There doesn't appear to be any real standard that most people use for this purpose afiak (myself as well as most people I work with generally just saves off log type files and does post run analysis in MATLAB).
I know/learning gnuplot syntax. I do not know superPlottingApiXX's syntax.
The feature set of gnuplot is almost ideal for the types of things I'd like to be able to do with this software.
However, if you have any particular suggestions in terms of C/C++ plotting libraries that seem like a good fit given the above list I am always interested in suggestions (warning: I have already looked around a good bit to find them).
gnuplot-cpp is an object-oriented C++ wrapper interface around a POSIX pipe connection with Gnuplot.
The example file compiled right away and the interfacing code looks decent; I'll be trying it in my current project.
there is a C2gnuplot library I wrote few years ago. It is very simple but may give you some tips. Basically it uses FIFO files to pass data into Gnuplot.It is able to generate animation from the plots. Here is a video created with the app. I hope this will be useful for you.
Slicker? Safe? Can you be more specific about your requirements?
It sounds like you are trying to do an animated visualization with a tool designed for generating static images. If your display is as simple as you say, why not write a quick GUI app (using the toolkit of your choice) to do the drawing instead?
I'm looking for options for abstracting database server details away from my application (in c++), I'd like to write my code to be independent of the actual database backend. I know MySQL has a nice library, but I don't want to be tied to a single database implementation. Are there good options for this?
SOCI is good. Supports multiple databases, works well, modern C++ style API, works with boost.
My opinion is to forget about a cross-database driver, and focus on finding or creating a cross-database Data Access Layer. A few reaons:
Complex queries (read: anything that's not a toy) invariably end up using one or two database-specific features. LIMIT and OFFSET for example, commonly used for paging, isn't universal.
Sooner or later you'll want bulk insertion, and you'll want it to be as fast as possible, because 3 hours is better than 6 hours. Every database has a different "optimum" way to do this, so your DAL will need to special-case this anyways.
Different databases may expose different constraint mechanisms—even custom column types—that can be be worth taking advantage of where possible (PostgreSQL is wonderful for this).
If you want to do any application level caching, you'll need a DAL anyways.
So, go ahead and use libmysql by itself - just hide it behind a compiler firewall in your DAL, and be prepared to swap it out later. You can protect yourself from shifting infrastructure without having to use a lowest-common-denominator SQL wrapper.
If that doesn't jive with you, check out SQLAPI++.
many apps use odbc (via unixODBC for instance), there's also otl. on windows you could use ado.net from managed c++ or the old ado com interfaces...
Qt provides a database abstraction layer. See: http://doc.trolltech.com/4.6/qsqldatabase.html.
libodbc++ provides a pretty good API.
Also the big guys Qt (see Kyle Lutz' answer) & wxWidgets have db abstraction layers, so it may be a good idea to use them if you plan to use/you're already using any other parts of those frameworks.
OpenDBX and libzdb are two lightweight candidates. Libgda for GNOME.