PROBLEM:
I am trying webrtc multi-videoconferencing by "muaz khan", but it taking to much cpu usage as I connected to 10 peers. My CPU usage is nearly 200%. Also In case of broadcasting "muaz khan" scalable broadcasting is not that effective because it using concept of multilevel
Question
1) Can any one suggest something that will take down cpu usage down & scalable broadcasting.
2) Any other option to Media server technique.
3) Also can any one tell me any open source "Media server technique", I have tried kurento's but they don't have many-to-many in node & they are not free right??
4) kurento provide Android & IOS sdk? If not then please tell me any Client like kurento(open source) which provide Android & IOS sdk.
Related
I want to detect low performance device in runtime in react native to disable complex lottie animation. I consider for use device model from react-native-device-info, but I should have a list of heigh performance phones
I'm also interested in this question and it would be fine to have some solution. I can think of using react-native-device-info and comparing following properties of device:
CPU architecture (32/64 bit)
total RAM available
total disk capacity
current android version
Maybe using these variables we are able to calculate some performance level with not that bad accuracy.
64bit + lets say at least 3GB RAM + 32GB capacity + one of newer Android version can be good indication that device should have some power inside.
on the other hands 32bit + 1/2GB RAM + max 8/16GB capacity + not that new Android version can lead to performance prblms.
Seriously let's talk about it :D Maybe we can find some good compromise and maybe write a lib or contribute to react-native-device-info with a feature that will try to suggest developers about device's performance.
consider use android version
we use this formula:
low android version === old phone === low performance
performance can be low if device is out of memory, too many applications opened, which browser used, etc... its hard to detect
when is neccesary, you can write small performance test in app before animations or on app load/initialization, and you can use these results.
It's possible to run any benchmark in background using web worker or use library like fireball-js, then compare the score.
My game is based on Flash and uses RTMP to deliver live video to players. Video should be streamed from single location to many clients, not between clients.
It's essential requirement that end-to-end video stream should have very low latency, less than 0.5s.
Using many tweaks on server and client, I was able to achieve approx. 0.2s latency with RTMP and Adobe Live Media Encoder in case of loopback network interface.
Now the problem is to port the project to Windows 8 store app. Natively Windows 8 offers smooth streaming extensions for IIS + http://playerframework.codeplex.com/ for player + video encoder compatible with live smooth streaming. As of encoder, now I tested only Microsoft Expression Encoder 4 that supports live smooth streaming.
Despite using msRealTime property on player side, the latency is huge and I was unable to make it less than 6-10 seconds by tweaking the encoder. Different sources state that smooth [live] streaming is not a choice for low-latency video streaming scenarios, and it seems that with Expression Encoder 4 it's impossible to achieve low latency with any combination of settings. There are hardware video encoders which support smooth streaming, like ones from envivio or digital rapids, however:
They are expensive
I'm not sure at all if they can significantly improve latency on encoder side, compared to Expression Encoder
Even if they can eliminate encoder's time, can the rest of smooth streaming (IIS side) support required speed.
Questions:
What technology could be used to stream to Win8 clients with subsecond latency, if any?
Do you know players compatible with win8 or easily portable to win8 which support rtmp?
Addition. Live translation of Build 2012 uses Rtmp and Smooth Streaming in Desktop mode. In Metro mode, it uses RTMP and Flash Player for Metro.
I can confirm that Smooth Streaming will not be your technology of choice here. Under the very best scenario with perfect conditions, the best you're going to get is a few seconds (absolute minimum latency would be the chunk length itself, even if everything else had 0 latency.)
I think most likely RTSP/RTMP or something similar using UDP is your best bet. I would be looking at Video Conferencing technologies more than wide audience streaming technologies. If I remember correctly there are a few .NET components out there to handle RTSP H.264 meant for video conferencing - if I can find them later I will post here.
I need to get the internet connection speed for the connected internet connection with objective c in Mac OS Application.
There's no "formal" way to do this. Also note that in practice "internet connection speed" makes very little sense. You probably mean "max bandwidth to your nearest gateway", but in a more general fashion it doesn't make much sense (think router with several network interfaces for instance).
Anyway, you won't find any API to do this. You're better off just optimizing for the "worst case scenario", and it will just go faster if the user has more bandwidth.
Also note that you might be able to tell if the iOS device is on WiFi or 3G though.
I have a piece of hardware that sends USB data over ethernet (only the data stored in the package will be send). On a remote PC the data is recieved via ethernet. How can I send this data to the USB driver so it translates the data into commands applications can use?
You're better off getting hardware that does the reciprocal, sends the IP-based USB information to the USB subsystem, rather than try and hack the software driver itself. I can't imagine your hardware vendor doesn't have a device that does this.
You need a server listening on whatever port/socket that you are trying to connect to. Twisted Matrix makes decent Python libraries for network communications.
I think this is going to be troublesome.
USB is generally set up to associate a driver with a connected device, based on the device's various ID numbers, as discovered during bus traversal.
Your data comes in over Ethernet, so the platform's USB driver stack won't know anything about the device in question. This means you somehow need to directly talk to the proper driver, and also get it prepared to handle events from a (from its point of view) non-connected device.
I can think of several reasons why even a well-designed USB stack won't handle this happily.
On Linux, you might be able to "cheat" by interpreting the data yourself and sending it on, using the same API:s the actual driver would have used. That won't work for any USB device of course, it requires you know what the device is.
It's doable on windows as well, but you need a lot of kernel/usb knowledge to make it work i don't think i will be wrong by estimating this task as few man years (you can reduce this estimation dramatically if you have a limited selection of devices/types of device to support.
You will need to develop a bus driver that will simulate the host controller driver to the native usb host, unfortunately this interface is not public and we did not managed to get MS cooperation on that.
There is additional option to work on hub level, instead on controller level, this interface is available, but i did not managed to find my notes on that.
You can download the evaluation version and investigate the driver stack it might give you a clue where to start.
I have been tasked to write a device driver for an embedded device which will communicate with the micro controller via the SPI interface. Eventually, the USB interface will be used to download updated code externally and used during the verification phase.
My question is, does anyone know of a good reference design or documentation or online tutorial which covers the implementation/design of the USB protocol stack/device driver within an embedded system? I am just starting out and reading through the 650 page USB v2.0 spec is a little daunting at the moment.
Just as a FYI, the micro controller that I am using is a Freescale 9S12.
Mark
Based upon goldenmean's (-AD) comments I wanted to add the following info:
1) The embedded device uses a custom executive and makes no use of a COTS or RTOS.
2) The device will use interrupts to indicate data is ready to be retrieved from the device.
3) I have read through some of the docs regarding Linux, but since I am not at all familiar with Linux it isn't very helpful at the moment (though I am hoping it will be very quickly).
4) The design approach, for now at least, it to write a device driver for the USB device then a USB protocol layer (I/O) would reside on top of the device driver to interpret the data. I would assume this would be the best approach, though I could be wrong.
Edit - A year later
I just wanted to share a few items before they vanish from my mind in case I never work on a USB device again. I ran into a few obstacles when developing code and getting it up and running for the first.
The first problem I ran into was that when the USB device was connected to the Host (Windows in my case) was the host issues a Reset request. The USB device would reset and clear the interrupt enable flags. I didn't read the literature enough to know this was happening, thus I was never receiving the Set-Up Request Interrupt. It took me quite a while to figure this out.
The second problem I ran into was not handling the Set-Up Request for Set_Configuration properly. I was handling it, but I was not processing the request correctly in that the USB device was not sending an ACK when this Set-Up Request came in. I eventually found this out by using a hardware USB protocol analyzer.
There were other issues that I ran into, but these were the two biggest ones that took me quite a while to figure out. The other issue I had to worry about is big-endian and little-endian, Freescale 9S12 vs USB data format (Intel), respectively.
I ended up building the USB device driver similar to UART device drivers I had done in the past. I have posted the code to this at the following URL.
http://lordhog.wordpress.com/2010/12/13/usb-drive
I tend to use structures a lot, so people may not like them since they are not as portal as using #defines (e.g., MAX3420_SETUP_DATA_AVAIL_INT_REQR 0x20), but I like them since it makes the code more readable for me. If anyone has questions regarding it please feel free to e-mail and I can try to give some insight to it. The book "USB Complete: The Developer's Guide" was helpful, so long as you knew what areas to concentrate on. This was a simple application and only used low-speed USB.
While writing a device driver for any interface (USB, Parallel port, etc...) the code needed to be developed would depend upon whether there is any Operating System(OS), RTOS running on that Processor/Micro controller.
e.g. if thats going to run say WinCE - It will have its own Driver development Kit , and steps to be followed in the device driver development. Same for any other OS like Linux, symbian.
If its going to be a plain firmware code(No OS) which is going to control the processor/microcontroller, then it's a different situation altogether.
So based on either of the above situation u are in, one needs to read & understand:-
1.) The Hardware Specification of the processor/micro controller development board - Register files, ports, memory layout, etc.
2.) USB spec
3.) Couple of pointers i found quickly. Google shud be ur friend!
http://www.lrr.in.tum.de/Par/arch/usb/usbdoc/ - Linux USB device driver
http://www.microsoft.com/technet/archive/wce/support/usbce.mspx
-AD
I've used an earlier edition of USB Complete by Jan Axelson. Indeed very complete.
From the editorial review:
Now in its fourth edition, this developer's guide to the Universal Serial Bus (USB) interface covers all aspects of project development, such as hardware design, device firmware, and host application software.
I'm curious, why did you pick the 9S12? I used it at a previous job, and was not pleased.
It had lousy gcc support so we used Metrowerks
which may have been okay for C, but often generated buggy C++
had a lousy IDE with binary project files!
The 9s12 was also slow, a lot of instructions executed in 5 cycles.
Not very power efficient, either.
no barrel shifter, made operations that are common in embedded code slow
not that cheap.
About the only thing I dislike more is an 8051. I'm using an ARM CortexM3 at my current job, it's better than a 9S12 in every way (faster clock, more work done per clock, less power consumption, cheaper, good gcc support, 32-bit vs. 16-bit).
I don't know which hardware you're planning to use but assuming that's flexible, STMicro offers a line of microcontrollers with USB/SPI support and a library of C-code that can be used with their parts. -- I've used their ARM7 series micros for years with great success.
Here is an excellent site maintained by Jonathan Valvano, a professor at the University of Texas. He teaches four courses over there (three undergraduate, one graduate), all are about using a 9S12 microcontroller. His site contains all the lecture notes, lab manuals, and more importantly, starter files, that he uses for all his classes.
The website looks like it's from the 90's, but just dig around a bit and you should find everything you need.
users.ece.utexas.edu/~valvano/
Consider AVR for your next MCU project because of it's wonderful LUFA and V-USB libraries.
I'm working on a project using the Atmel V71. The processor is very powerful and among lot's of high end connectivity offered on chip is a USB engine that will do device or host modes for 480 Mhz or 48Mhz (not USB 3.0). The tools are free and come with a number of host and device USB example projects with all the USB stack code right there. It supports 10 end points and all the transfers are done via DMA so you have most of the processor horsepower available for other tasks. The Atmel USB stack works without needing an RTOS