CCTV | C Compile-Time eValuator for scheme | Interpreter library
kandi X-RAY | CCTV Summary
kandi X-RAY | CCTV Summary
The pure functional core of the scheme metacircular evaluator turns out to be fairly easy to implement entirely in C++ template metaprogramming (TMP). This repo implements a simple scheme dialect called "CCTV-scheme" based on C++ TMP, by which you can write scheme code using C++ template like:.
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QUESTION
Bit of a beginner question here; I currently have a pandas df with one column containing various different strings. I have some more columns which are currently empty. Example of first few rows below;
...ANSWER
Answered 2021-May-17 at 12:17Firstly create/define a function:
QUESTION
So I am fetching an array of objects to fill my datatable, there is no issue with the fetching as i get the data I need in the format I need. I retrieve it from my redux store like so:
...ANSWER
Answered 2021-Apr-21 at 13:43I would break your useEffect to two since they handle different parts of your code, one to dispatch a fetch and the other to massage the data when received.
QUESTION
So, I made 2 scripts that convert CCTV footage in mp4 videos. One of them is just a -vcodec copy
and creates a mp4 with the same size of the footage (huge, btw) and my other alternative was tweak with some parameters and figure out what was the best I could do without sacrifice too much quality and make it "fast".
Then I come up with c:v libx264 -crf 30 -preset veryfast -filter:v fps=fps=20
which took something like 2 secs in my machine to run an average 6MB file and transform into a 600kB file.
Happy with the results I decided to put it on AWS lambda (to avoid bottlenecks), and then people started to complain about missing files, so I increase the timeout and the memory to 380MB. And even after that, I am still getting a few lambda errors...
Anyway, the lambda is going to cost me too much compared to just store the file without compression, there is another way to decrease size without sacrificing time?
[UPDATE] I crunch some numbers and even tho using lambda is not what I expected, I am still saving a lot of cash monthly by reducing the file size 10x times.
As asked, this is the logs for the ffmpeg.
...ANSWER
Answered 2021-Feb-17 at 17:55You have to choose a balance between encoding speed and encoding efficiency.
- Choose the slowest
-preset
you have patience for. - Choose the highest
-crf
value that provides an acceptable quality.
See FFmpeg Wiki: H.264 for more info.
libx265If libx264 does not make a small enough file try libx265, but it takes longer to encode.
See FFmpeg Wiki: HEVC/H.265 for more info.
Hardware accelerated encoderIf you have the proper hardware, then you can use NVENC, QuickSync, or some other implementation.
Encoding will be fast, but it will not match the quality per bit provided by libx264 or libx265.
See FFmpeg Wiki: Hardware for more info.
QUESTION
Recently I create my first serverless service. Nothing fancy, just a script that uses FFMPEG to encode some CCTV footage and reduce quality.
After a couple of days, I realize that many of my footage where not there. After stare for some time at the aws lambda metrics panel, I assume that the cause of the problem was too little time and to little memory, so I cranked up the timeout (8 minutes) and max memory (380MB). And then I left it work for a couple of days to see if it would get better. Fast forward to today, I log in on aws and notice that I was never using more than 95MB of memory (as seen on the image).
Is this right? Also, looking at the graph, I notice that I still get some errors. Increase the timeout is the solution?
Sorry for the poor quality of the question, I really tried to lookup.
...ANSWER
Answered 2021-Feb-05 at 13:47Available RAM is not the only thing that's influenced by the Memory setting, which is a bit counterintuitive at first. The memory setting in a Lambda function influences:
- The amount of compute (vCPUs) that's available to the function
- The amount of network throughput that's available
- The amount of system memory / RAM that's available
All of these scale based on the memory. You can think of it like this: If you provision 128MB RAM, you also get about 1/8 of a vCPU, if you go to 256 MB, you get a quarter of a vCPU. These are not exact numbers, but it's a useful mental model. Somewhere between 1024 and 1280 MB you get a full vCPU and afterwards a second vCPU is added.
Your workload seems CPU intensive (since there's not GPU to offload it to), so I'd try to increase the Memory to give Lambda more compute power to see how it behaves.
QUESTION
I am designing a game primarily centered around seeing from the views of CCTV cameras. The cameras are supposed to automatically rotate. The code works flawlessly up until the point where the camera needs to change its rotation direction. The camera begins to switch between clockwise and counter-clockwise rapidly, causing the camera to wiggle and not rotate. The code is:
...ANSWER
Answered 2020-Dec-20 at 21:53In each frame you are adding (turnSpeed * Time.deltaTime) to the current angle. In the likely case that it passes 300 or 0 (For example 298.5f + 2.5f will pass 300) the camera will start to turn clockwise and counter-clockwise each frame. (298.5f, 301.0f, 298.5f, 301.0f and so on). You should be using mathematical functions that we are sure that will not exceed some values. Sin() function is a good example since we know that it will always be in the range of -1 and 1. Something like this should give you the idea:
QUESTION
I have problem with load threejs model by objectloader, i add newest ThreeJs library version to get more feature like create text, using objectloader... Here is my code:
...ANSWER
Answered 2020-Nov-30 at 07:28It looks like you're using another version of three.js and referencing it globally, which is not delivered by Forge Viewer itself, and it will conflict with Forge Viewer one. As Petr mentioned here (upgrade three js version in autodesk forge viewer), Forge Viewer uses self-maintained three.js r71 removed most of the built-in three.js functions.
If you want to use missing features from Forge Viewer's three.js libraries, I would advise you to use some modern development tools such as bundlers (Webpack is the most popular one). You can leverage ES6 modules and import to your app only the strictly needed dependencies. The threejs-full-es6 package lets you import Three.js features to your app independently, so in that case, we can import THREEE.ObjectLoader,
and all other required dependencies will be taken care of by the package implementation.
See Forge community blog here: https://forge.autodesk.com/blog/how-add-newest-threejs-features-forge-viewer
QUESTION
For my image processing practice, I want some of the images from this site: https://511ny.org/cctv and it seems that I have no access to their 'src' to use in BeautifulSoup and extract the images. If you may have any solution for this issue please inform me. here is my code which didn't get any response:
...ANSWER
Answered 2020-Oct-24 at 21:13images in this website are not present in the initial html file but loaded dynamically through execution of javascript and beautifulsoup/urllib are not going to execute them for you.
to crawl dynamic websites you should use a sort of headless browser like selenium which has python library to communicate with it. these browsers are just like normal browsers but with one difference; they are controlled by your code instead of the user.
a better alternative to selenium would be puppeteer but i used it in node.js and i'm not sure of it's python binding quality.
QUESTION
I am working on a machine learning project and need a LOT of pictures for the data set that will train my program. The website https://its.txdot.gov/ITS_WEB/FrontEnd/default.html?r=SAT&p=San%20Antonio&t=cctv has pictures that are updated every six minutes. I need to save the image at LP 1604 at Kyle Seal Pkwy, but can't figure out how. I'm trying to right click on the image using action chains to save the image. Here's what I have so far:
...ANSWER
Answered 2020-Sep-28 at 17:36I think that it could be help you do save the images in your Pc:
QUESTION
I am trying to scrape video frames from trafficview.org and can't seem to figure out how to decode the data.
I wrote a few lines of code based on tutorials on this websocket_client to access a live streaming websocket and receive the messages directly.
I have monitored the messages coming in via the network tab on Chrome and also dug into the output from the code below and am fairly certain the data are streaming in as a fragmented MP4. Below are the first 100 or so byte/messages:
b'\xfa\x00\x02\x86\xf1B\xc0\x1e\x00\x00\x00\x18ftypiso5\x00\x00\x02\x00iso6mp41\x00\x00\x02jmoov\x00\x00\x00lmvhd\x00\x00\x00\x00\xdb\x7f\xeb\xb2\xdb\x7f\xeb\xb2\x00\x00\x03\xe8\x00\x00\x00\x00\x00\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
Throughout this output, there are lots of moof and mdat pairs. Lets say I let this code run for 30 seconds, how can I convert this raw byte string into an mp4 file?
...ANSWER
Answered 2020-Sep-15 at 22:07ws = create_connection(url, headers=headers)
# Then send a message through the tunnel
ws.send('ping')
start = timeit.default_timer()
flag = True
output = []
while flag:
output.append(ws.recv())
if timeit.default_timer() - start > 90:
flag = False
result = output[0][8:]
for msg in output[1:]:
if msg[0] == 249:
moofmdat = b''
moof = b''
continue
if msg[0] == 252:
vidbuf = msg[4:]
if msg[0] == 251:
moof += msg[4:]
if msg[0] == 254:
mdat = msg[4:]
if msg[0] == 255:
moofmdat += moof
moofmdat += mdat
moofmdat += vidbuf
result += moofmdat
with open('test.mp4', 'wb') as file:
file.write(result)
QUESTION
i am working on program for tracking people from cctv cameras, where i have video input from cctv camera and i have 2D top view image of building that contains all cctv cameras. when i detect person in the scene i draw bounding box around the person, and this bounding box has center point represented as x,y in image coordinates system, and what i want to do is to convert this bounding box center point to another 2D point in building image coordinates system. can any one give me a hint or idea ???
here the image from cctv camera, and the image of building where the red line in cctv image is the line that i have and the red line in building image is the line i want to obtain.
CCTV camera image :
building image :
...ANSWER
Answered 2020-Aug-30 at 06:40So because the camera is projecting a 3D world down to 2D and then you want to get it from another 2D perspective there can be errors. For instance the center point of the rectangle of the person could either be ~2.7ft off the ground where they are standing OR could be the floor if the person wasn't there. Those would be 2 very different places on your birds eye view map.
However, since this is for tracking people, you could make the assumption that everyone is approximately the same height and assume the center of the rectangle is always approximately 2.7ft off the ground. If you make this assumption then the problem is more tractable.
With that assumption, what you could do is have a calibration phase. So you could have the person stand at the end of the hallway and see what coordinates that is on the camera and what coordinates on the map. Then have them walk up in front of the camera and see the coordinates on the camera and coordinates on the map. With these two points you could do a linear interpolation to be able to figure out where in the hallway someone is based on the camera. You would need to do this calibration for each camera that you have but it should give fairly accurate results.
Let (x1, y1)
be the camera coordinates at end of hall and (X1, Y1)
map coordinates at end of hall. Then let (x2, y2)
be camera coordinates when close to camera and (X2, Y2)
map coordinates close to camera. So then find a linear A
such that
A(x1, y1) = (X1, Y1)
and A(x2, y2) = (X2, Y2)
You can solve this as a matrix equation (not sure how to type math in here)
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