I'm hoping to connect two USB barcode scanners to a single computer, allowing two people to scan ticket barcodes simultaneously. If both people scan at the same time, however, the input from STDIN will get messy.
Is there a way to set up different STDIN streams, each tied to a specific USB port? The console script is in Ruby, though pointers in any language would be much appreciated.
Try connecting 2 USB barcode scanners first and test if what you are afraid of happens. I suspect all barcode digits are sent in a single burst while interrupts from other keyboard-like devices are on hold - so you won't get two barcodes "interlaced" together.
It's impossible to have more than one stdin, not literally. Other options will depend based on the OS you are on - on linux maybe the drivers provide you different character devices for different scanners. On Windows i believe you will have to learn talking the USB HID protocol... best if you don't have to do any of that.
To answer your question directly, there is no way to have more than one STDIN. You're best bet would be to read the data from a file (I would think you should have a character device or something for this scanner)
What if you use a Mutex to synchronize them so only one scan can be processed at a time?
Here's a tutorial on working with threads in Ruby
http://ruby-doc.org/docs/ProgrammingRuby/html/tut_threads.html
Related
As read on topic here How to find the unique serial number of a flash device? and especially here How to get manufacturer serial number of an USB flash drive? I know it is possible to get properties of hardware devices (particularly hard drives and usb drives...) using WMI Win32_PhysicalMedia and Win32_DiskDrive, which I'm getting done successfully.
However, I really want to know about the safety of these informations.
PhysicalMedia property SerialNumber returns the actual serial number of the main hard drive, while using other Win32_LogicalDisk and other calls we can map the drive letter of flash storage to actual Win32_DiskDrive device, and from there read properties like Name, Model, FirmwareRevision, SerialNumber, DeviceID, Manufacturer...
Now, DeviceID is generated by Windows / Pc itself, while SerialNumber should be the one that manufacturer added to the physical flash drive.
Manufacturer in most cases returns "Standard" something, Name is also of no use, while SerialNumber actually gets me a something that looks like unique ID, (I've read that in some cases this is not returned, so PNPDeviceID should be used instead? , Model gives the actual model of the flash drive, and FirmwareRevision just a number that could be used to add safety switch to the licensing, but is not vital.
However, the only one of these that seems / should be actually safe to use is SerialNumber, right?
So, the question here goes: Which level is Win32_DiskDrive actually reading this info from? Is it possible to fake that at all (Ok, letalone the actual lowlevel hacking stuff or driver injection etc...(??)), and if so, how hard it is?
If there's a known way / guide / example, I'd be also happy to read it. (not necessary info looking for here though.)
This is not for intention of bypassing some licensing. I'm making licensing for my SW, and am curious, whether it would be safe enough to use USB drive's SerialNumber property, and lock license against the presence of that USB flash, for which the license was bought for? Basically to use it as kind of a dongle, but not like the dongles actually work (using communication with the actual hardware inside the dongle...)
I know it may not seem as a safe solution, as flash drives dies quite often these days, or get lost etc, but this is just to add an option to my licensing from "Per PC" to "Portable - per USB device".
Thanks for any info!!!
EDIT:
I am completely aware that bypassing these kind of safety switches is very possible. Of course, even Windows itself is not licensed in a way that couldn't be hacked, nor Adobe, ProTools etc, (software that is widely used and costs a lot!).
But that wasn't a real question, and also, that's not the case for me -> the software will not be that expensive and not used by that much people, that I'd be afraid to drag interest in someone who will do extensive programming to make a patch/crack for it. Regular debugger use and workaround is pretty unlikely to be used by regular client who would need the software, ( and also, since it is something to be used in business environment, where stability is vital, I doubt they will really play around that...).
Main point here:
It is possible for sure, but: HOW hard is it to do for a regular person? (I know, the answer is: depending on your code.)
Main question of the post: Is it possible to change the ID on the USB itself, OR to make an app that will fake that data to my app? If it is, I'm sure it might be easier than making a crack/patch, that's why I wanted to know, whether WMI reads explicitly from hardware, or could one make an app that would pass fake data to it?
WMI just returns what the hardware tells it. It's as unique as the hardware. Which ultimately depends on the vendor.
But...
If someone has an administrator account to the computer†, then there are very few things that can be done to keep them from just hooking up the kernel debugger to your program and overriding your checks, or recording the raw USB communication session and replaying it on an unauthorized system. The real dongles do some to mitigate this, by having the hardware generate a response to a particular challenge. The challenge/response changes for each request, so it's not as susceptible to replay attacks, but the debugger tricks still work.
This is the real problem with the serial number approach. Uniqueness is not the primary concern for dongled software. The primary concern is unpredictability.
An illustrative example-
Let's say that I'm a bouncer at an exclusive night club. We're so exclusive that you have to answer a question to get in. You really want to get in, but no one will tell you the answer to the question. One night, you hatch a plan. You hang out in the alley and listen to the conversations that I'm having with the patrons trying to enter the club. It doesn't take you long to realize that I'm asking everyone the exact same question, and you're in. (This is the serial number approach)
After a while, I notice that there are a lot of people coming into the club that I've never seen before, and begin to suspect something. The people we really want to allow in are all given a card with a formula‡ on it. Whenever they come to the door of the club, I give them a number and they apply their formula and tell me the result. Since I also know the formula, I can tell if they are really allowed in. Now, even if you hear the entire challenge and response, without the formula, you aren't getting in. (This is one common approach taken by dongles.)
But what about the debugger? The debugger just made herself the club's owner, fired me, and can come and go as she pleases.
†Or has physical access to the machine and a password reset disk.
‡Stop laughing, this could totally happen. :)
Photo credit: Guillaume Paumier, CC-BY. Found on the Wikimedia Commons 7-Oct-15
Edit to address the question edit:
HOW hard is it to do for a regular person? (I know, the answer is: depending on your code.)
The question is how skilled is the 'regular person'? If you're talking about software/electrical engineers, then this is a trivial task. If you're talking about sales/marketing then it's a challenging task.
Is it possible to change the ID on the USB itself, OR to make an app that will fake that data to my app?
It depends and Yes. Changing the ID on the device itself is possible with some devices, and impossible with others. Software to spoof/man-in-the-middle the USB communication, or to create a virtual USB device is possible.
If it is, I'm sure it might be easier than making a crack/patch, that's why I wanted to know, whether WMI reads explicitly from hardware, or could one make an app that would pass fake data to it?
As I led with above, WMI reads from the hardware. This can be intercepted or bypassed.
Some ways to bypass the check:
Make a virtual USB device
Modify the USB MSD device driver to report the same serial number for all devices.
Build hardware using commercially available cheap host controllers that identifies with the same information as the authorized device. ($10 worth of raw components and a little bit of time.)
Redirect the system calls to/from USB to a compromised library.
Note also that:
Some places have restrictions on USB storage devices, ranging from discouraging their use, to outright bans. This would prevent your software from being used in sensitive computing environments processing private data, like credit cards, PII, trade secrets, classified information, etc. (In the US many governmental agencies have outright bans on USB storage devices, and block the install of any MSD.)
The Mass Storage specification doesn't require serial numbers. They are usually there, but they don't have to be, and many low-cost vendors
A USB PKI token costs a little bit more, but would probably do what you want. Here's an example from Safenet (Disclaimer: I am in no way affiliated with Safenet Inc, and you should evaluate all the possible options from all vendors. I suggested this because it was the first thing that came up through CDW, and the price was ~$30)
I have a chinese charge controller reporting data to a windows software via a serial cable.
I have managed to sniff the COM port and successfully isolated the data being sent by the software to request the controller to transmit sensor data.
The data being returned by the controller is a single line:
(for example)
..p...............!............ª.x
Somehow the damn thing is updating at least 4 numerical values in the software with that single line. Each second a line like that is returned, but I'm very confused because the data shown in the app is sometimes the same but the serial data received to represent such data is different. As if it was encrypted somehow (which is stupid).
Here is an example of 10 different lines being reported back from the controller. These are received one each second.
..p€...........................ª.Ï
..p...................!........ª.w
..p€...........................ª.Ï
..p............................ª.O
..p............................ª.Q
..p............................ª.P
Funny thing is each one of those 6 lines is representing EXACTLY the same data values on the receiving software (measuring voltage and amps).
The windows software is a very crappy VB.6 exe which i was able to decompile, but it seems to rely heavy on p-code, PCOMM.DLL, MXTOOL and other crap.
To anybody with serial expertise:
is this controller encrypting its sensor data?
if so, what technique should i use to figure out how it is encrypting its 4 values?
Finally, do you suggest any serial apps or decompilers that will aid in this?
Pedro
Are you sure you are using the correct baudrate to read in the data?
Are you using the correct parity and data bits and stop bits ?
Do you have any documentation of the device?
Do you know what the data should look like?
Does the data consist of normal ascii characters or is it some chinese script?
OK, the first issue. I am trying to write a virtual soundboard that will output to multiple devices at once. I would prefer OpenAL for this, but if I have to switch over to MS libs (I'm writing this initially on Windows 7) I will.
Anyway, the idea is that you have a bunch of sound files loaded up and ready to play. You're on Skype, and someone fails in a major way, so you hit the play button on the Price is Right fail ditty. Both you and your friends hear this sound at the same time, and have a good laugh about it.
I've gotten OAL to the point where I can play on the default device, and selecting a device at this point seems rather trivial. However, from what I understand, each OAL device needs its context to be current in order for the buffer to populate/propagate properly. Which means, in a standard program, the sound would play on one device, and then the device would be switched and the sound buffered then played on the second device.
Is this possible at all, with any audio library? Would threads be involved, and would those be safe?
Then, the next problem is, in order for it to integrate seamlessly with end-user setups, it would need to be able to either output to the default recording device, or intercept the recording device, mix it with the sound, and output it as another playback device. Is either of these possible, and if both are, which is more feasible? I think it would be preferable to be able to output to the recording device itself, as then the program wouldn't have to be running in order to have the microphone still work for calls.
If I understood well there are two questions here, mainly.
Is it possible to play a sound on two or more audio output devices simultaneously, and how to achieve this?
Is it possible to loop back data through a audio input (recording) device so that is is played on the respective monitor i.e for example sent through the audio stream of Skype to your partner, in your respective case.
Answer to 1: This is absolutely feasable, all independent audio outputs of your system can play sounds simultaneously. For example some professional audio interfaces (for music production) have 8, 16, 64 independent outputs of which all can be played sound simultaneously. That means that each output device maintains its own buffer that it consumes independently (apart from concurrency on eventual shared memory to feed the buffer).
How?
Most audio frameworks / systems provide functions to get a "device handle" which will need you to pass a callback for feeding the buffer with samples (so does Open AL for example). This will be called independently and asynchroneously by the framework / system (ultimately the audio device driver(s)).
Since this all works asynchroneously you dont necessarily need multi-threading here. All you need to do in principle is maintaining two (or more) audio output device handles, each with a seperate buffer consuming callback, to feed the two (or more) seperate devices.
Note You can also play several sounds on one single device. Most devices / systems allow this kind of "resources sharing". Actually, that is one purpose for which sound cards are actually made for. To mix together all the sounds produced by the various programs (and hence take off that heavy burden from the CPU). When you use one (physical) device to play several sounds, the concept is the same as with multiple device. For each sound you get a logical device handle. Only that those handle refers to several "channels" of one physical device.
What should you use?
Open AL seems a little like using heavy artillery for this simple task I would say (since you dont want that much portability, and probably dont plan to implement your own codec and effects ;) )
I would recommend you to use Qt here. It is highly portable (Win/Mac/Linux) and it has a very handy class that will do the job for you: http://qt-project.org/doc/qt-5.0/qtmultimedia/qaudiooutput.html
Check the example in the documentation to see how to play a WAV file, with a couple of lines of code. To play several WAV files simultaneously you simply have to open several QAudioOutput (basically put the code from the example in a function and call it as often as you want). Note that you have to close / stop the QAudioOutput in order for the sound to stop playing.
Answer to 2: What you want to do is called a loopback. Only a very limited number of sound cards i.e audio devices provide a so called loopback input device, which would permit for recording what is currently output by the main output mix of the soundcard for example. However, even this kind of device provided, it will not permit you to loop back anything into the microphone input device. The microphone input device only takes data from the microphone D/A converter. This is deep in the H/W, you can not mix in anything on your level there.
This said, it will be very very hard (IMHO practicably impossible) to have Skype send your sound with a standard setup to your conversation partner. Only thing I can think of would be having an audio device with loopback capabilities (or simply have a physical cable connection a possible monitor line out to any recording line in), and have then Skype set up to use this looped back device as an input. However, Skype will not pick up from your microphone anymore, hence, you wont have a conversation ;)
Note: When saying "simultaneous" playback here, we are talking about synchronizing the playback of two sounds as concerned by real-time perception (in the range of 10-20ms). We are not looking at actual synchronization on a sample level, and the related clock jitter and phase shifting issues that come into play when sending sound onto two physical devices with two independent (free running) clocks. Thus, when the application demands in phase signal generation on independent devices, clock recovery mechanisms are necessary, which may be provided by the drivers or OS.
Note: Virtual audio device software such as Virtual Audio Cable will provide virtual devices to achieve loopback functionnality in Windows. Frameworks such as Jack Audio may achieve the same in UX environment.
There is a very easy way to output audio on two devices at the same time:
For Realtek devices you can use the Audio-mixer "trick" (but this will give you a delay / echo);
For everything else (and without echo) you can use Voicemeeter (which is totaly free).
I have explained BOTH solutions in this video: https://youtu.be/lpvae_2WOSQ
Best Regards
Is it possible to use the NSSpeechRecognizer with an pre-recorded audio file instead of direct microphone input?
Or is there any other speech-to-text framework for Objective-C/Cocoa available?
Added:
Rather than using voice at the machine that is running the application external devices (e.g. iPhone) could be used for sending just an recorded audio stream to that desktop application. The desktop Cocoa app then would process and do whatever it's supposed to do using the assigned commands.
Thanks.
I don't see any obvious way to switch the input programmatically, though the "Speech" companion guide's first paragraph in the "Recognizing Speech" section seems to imply other inputs can be used. I think this is meant to be set via System Preferences, though. I'm guessing it uses the primary audio input device selected there.
I suspect, though, you're looking for open-ended speech recognition, which NSSpeechRecognizer is not. If you're looking to transform any pre-recorded audio into text (ie, make a transcript of a recording), you're completely out of luck with NSSpeechRecognizer, as you must give it an array of "commands" to listen for.
Theoretically, you could feed it the whole dictionary, but I don't think that would work since you usually have to give it clear, distinct commands. Its performance would suffer, I would guess, if you gave it a bunch of stuff to analyze for (in real time).
Your best bet is to look at third-party open source solutions. There are a few generalized packages out there (none specifically for Cocoa/Objective-C), but this poses another question: What kind of recognition are you looking for? The two main forms of speech recognition ('trained' is more accurate but less flexible for different voices and the recording environment, whereas 'open' is generally much less accurate).
It'd probably be best if you stated exactly what you're trying to accomplish.
Many USB devices contain a unique serial number (which is actually a Unicode string) which the host can use in conjunction with the 16-bit vendor and product ID numbers to uniquely identify the device.
I'm trying to figure out how to write a Windows application that would be able to display a list of all USB human interface devices attached to the system. The list would have one row for each HID, including system keyboards. There would be columns in the list for the vendor ID, product ID, and serial number.
I can get a list of USB HIDs by calling SetupDiGetClassDevs with the GUID returned by HidD_GetHidGuid and looping through the result by repeatedly calling SetupDiEnumDeviceInterfaces. I can then call SetupDiGetDeviceInterfaceDetail to get the path to each device, which I can open with CreateFile, so long as I am careful to request neither read nor write permission, which would be denied for a system keyboard. From there I can get the vendor and product ID numbers by invoking HidD_GetAttributes.
What I'm having trouble figuring out is how to retrieve the serial number string. When I search for solutions to this problem, I find a lot of information about how to get serial numbers for USB mass storage devices, but nothing that looks like it might apply to any other type of USB device. I would be happy to discover either a generic method or a HID-specific method of retrieving the serial number string.
I have a feeling that the Win32 port of libusb could manage this without too much trouble, but unfortunately I need a solution that depends only on libraries that come with Windows, such as the setupapi and hid DLLs that contain the functions mentioned above.
Any suggestions would be very much appreciated!
It turns out that HID.dll defines a function called HidD_GetSerialNumberString that does exactly what I want, given the handle I got from CreateFile as described above. Just tried it out and it works great. There are also HidD_GetManufacturerString and HidD_GetProductString functions to retrieve the other string descriptors referred to in the device descriptor, and even a HidD_GetIndexedString to get an arbitrary string descriptor given its index (presumably because the HID descriptor is allowed to contain string descriptor indices). I feel pretty silly now -- the answer was right there under my nose this whole time.
Thank you all for taking the time to read and answer my question! I'm going to go ahead and accept Alphaneo's answer since it sounds quite promising, and in fact I was waiting for the DDK to download when I stumbled across this answer.
Have you tried the USBVIew source code that comes along with the DDK. The USBView tool displays serial number for any USB device, and the source is shipped with the DDK.
Have you tried searching for the documentation of the HID definition of input records, output records and features records for Hid keyboards. This should show you the list of "things" you can get out/in of a keyboard through HID.
Also, I know it is possible to enumerate the HID record definition by software. I did something similar about 1 year ago, but I cannot remember the details at the top of my head. Doing so would allow you to see what the keyboard USB class is publishing as a standard interface.
I hope it can get you a few pointers to find out what you are looking for. Sorry I could not be more precise!
I recommend this book USB Complete. Chapter 4 Enumeration: How the Host Learns about Devices has the information you need.
This page has many links to information and for you links to libraries and utilities you can use.
you can use GetVolumeInformation for getting the serial number of any hardware attached.