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How to offer multiple resolutions under device (v4l2loopback)?
Idea is that depending on what would be requested as read of stream, different command would be run.
Background is that v42loopback is fed by other stream and is to be used from browser level and browser dynamically changes resolution (Jitsi) or user would be the one selecting it.
Therefore preferably, if i.e. 1920x1080 is requested, v4l2loopback device is fed with such stream by the source and if other, then parameters are adjusted. At the same time request to v4l2loopback device (/dev/video42 or any number) could be 640x480 and there's no reason for to feed the loopback device with FHD at that time.
This might be more of RFE as might require some code changes. The resolution would have to be passed over and calling script with parameters. On the same tune, type of stream could be requested, i.e. h264, VP8, etc. and obviously it is impossible to feed multiple streams like this to loopback device in parallel.
Due to bandwidth/cpu power it is not possible to provide continuous feed with multiple resources, hence the need.
speaking as v4l2loopback upstream: you can't.
what you can do is create multiple devices with different resolutions.
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Closed 7 years ago.
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Just how do they differ in their working or storing of files?
People have been saying Ex-FAT is a better file system, and not to use NTFS so much. But how do they differ in actual working. Can anyone explain?
One very important difference comes about if you use the EFS "Encrypted" attribute (EFS stands for Encrypting File System ).
EFS is transparent. You don't see it. Files are encrypted on the disk, but are automatically decrypted when you access them.
for more media that needs to move around, FAT is usually more handy because NTFS has security attributes that get tied to the local computer by default.
exFAT does (better) which NTFS doesn't which is useful when using it for more removable mass storage .
difference between FAT32 , NTFS and EX-FAT
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I just recentely started working with a new board: a AT91SAM7X-EK. I would like to get more information about the board's processor (AT91SAM7X256) and the board's flash. So I looked at a pretty detailed data sheet and a summary of the data sheet, but have been unsucessfull (so far) of finding the information I want. I would appreciate if anyone could help me on the following aspects of the board:
How do I connect to the board? Is it through ssh? If so, how is it possible to recuperate the board's IP address. I have an ethernet cable for the connection.
How do I load an application onto the board's flash? For example, I would like to cross compile (using a toolchain I've already installed - arm-none-eabi) a simple hello world program in C to load onto my board. How would I go about doing so?
I would appreciate any help on this issue.
The board is supplied "bare-metal" - no code, no OS. You will not be able to run Linux on an AT91SAM7X-EK - it has insufficient memory resources and rins at 30MHz tops (and has no MMU).
You need a hardware JTAG or DBGU interface device and a tool-chain that will work with it.
You should probably also be looking at the datasheet for the board itself. From the Getting Started section of that:
The AT91SAM7X-EK evaluation board is delivered with a DVD-ROM containing all necessary
information and step-by-step procedures for working with the most common
development tool chains. Please refer to this DVD-ROM, or to the AT91 web site,
http://www.atmel.com/products/AT91/, for the most up-to-date information on getting
started with the evaluation kit.
So start there.
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How can I park the hard drive using C?
Park: To move the hard drive head from the hard drive to a safe location. This was done
to make sure the head would not damage the disk when the computer shuts down.
I'm just curious.
This hasn't been needed in many years. Modern hard drives will automatically park the read heads when shutting down. Also, as mentioned in Oli Charlesworth's comment, that functionality would have to be provided by some sort of device driver and its associated API. There's nothing in C that you can just call to do that.
It's no longer necessary to park the HD heads, as most HDs do it automatically nowadays, and are pretty good at protecting yourself. However, should you wish to pursue further, look at this detailed description of interrupt 13H. Seems like the function 19H may achieve what you need.
But why would you like to do this? This can easily hard crash your OS, since your HD would probably be busy doing other things at the time (such as basic OS services, and other applications). And there's a good chance of data loss from this crash, as the applications probably won't have a chance to flush data to the HD - since you just parked it.
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I am working on an online application that will also allow uploads of image files. The server handling the upload is written in C. So I was thinking if it was possible to upload malicious content. I am talking about viruses or malicious code or the like. I will only allow the upload of images so I can check the MIME-type and also the file suffix. But I am not sure if this is enough. The uploaded pictures will be delivered automatically via an HTML <img> tag.
I know that in the past images have been used to provoke buffer overflows and other unpleasant stuff. But maybe this isn't my responsibility to check but rather on the end of the browser to not allow image processing to expose vulnerabilities?
In short: When offering a service that depends on images provided by the users what can I do to prevent my server of becoming a distribution center of Malware? What are best practices regarding this concern? Would I go ahead and check the uploaded file via a certain algorithm or a certain library? Would that open vulnerabilities on my end? Is it my concern at all?
Edit: I may not have been specific of the mode of operation of the file uploading part. It is a module of nxweb a server written in C as is the module. So I am looking for ways to validate the file in that module.
Just test your file: Images (to confirm they are images) and executables (to discard them).
In order to test images, you can try open it with ImageMagick or OpenCV or FFmpeg or similar libraries that allow you to open several different formats! If the file can't be open as image, it's not an image!
Testing only images is just fine, but if you wanna test executables to get even more precision result, look for the PE format (Windows), Linux ELF, Mach-O (Mac OS X) and so on... they are not hard to parse. There's a lot of open source for this.
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I'm making a network manager program as a small project, and I want it to be able to access data on my Airport Extreme (most importantly, the DHCP client list).
There has to be a way of accessing the client list file from the Airport Extreme, after all, Airport Utility can do it. All I want to do is read the data from the file/list.
If anyone could even point me in the right direction, that would be great. I'm also hoping that I can get this program to run on all *nix machines, not just a mac (so any Airport utility hacks wouldn't really help).
You can do this via SNMP. Get hold of an SNMP browser such as GetIF and browse around the Airport via its address to see exactly what's in there, then use an SNMP library to get hold of the same information yourself in your application.
Network management essentially is SNMP. I'm surprised you hadn't come across it already.
I can't leave a comment so I will leave an answer. I don't have a solid answer but I have a few bread crumbs that might be helpful.
see the comment on page 5 — https://discussions.apple.com/thread/5101886?start=60&tstart=0 by user "_r_s_"
Also
1) Open airport utility
2) Double click your airport device from the window or click the device and then click the edit button.
3) Now go to File>Export Configuration File
4) Open the .baseconfig file in your favorite editor
5) Now go to http://aldentech.wnyric.org/webshare/mkempste/AirPort%20Utility%20copy.app/Contents/Resources/English.lproj/AirPortSettings.strings to help you sort out what all the strings mean.
6) Edit your base config file — Use the site below to find out the strings meaning in the .baseconfig file and edit the file to yield the result you are looking for.
7) Import the file back to your airport device and it should give you the features it is capable of.
I am posting these steps because Apple has removed SNMP for Airport Utility but they appear to be in the XML.
If you are willing please leave a link to your project.