We're working on a system to stream live sports events from the local high school stadium. We're feeding three IP streaming cameras into a laptop and switching between them with a DirectShow application we built in Visual Studio. We would like to superimpose a scoreboard and subtitles identifying the people onscreen but have run up against a problem: Once the DirectShow filter graph is running, it doesn't allow the file capture filter to reload the file so we can't change the score or subtitles! We tried making StreamBufferSinks to isolate the file capture modules so we could shut them off to reload the graphics, but could never get that to work...
Are we barking up the wrong tree? Is there a better way to do this? If DirectShow is the best solution, what is the best way to superimpose multiple .TGA, PNG or XAML files onto the video being mixed in VMR9 in a way that they can be updated during the game?
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I have a device streaming data to the PC and I would like to use R to produce real-time streaming plots. I realize that Javascript is probably the best tool for this, but I don't have the skill set for reading data and plotting in Javascript.
I am aware of gganimate, gifski, etc. for animated gifs, but I don't think those will be able to stream data.
I have tried Shiny with invalidateLater and it works, but struggles to update faster than about 5 frames per second.
I have tried to run an R process to generate images on a timer and a simple html page that loads the image every 100 ms, but this produces frequent broken links when the html page is trying to load an image that R is actively writing.
Are there any other options in R that don't involve learning Javascript or Javascript packages? Any other general advice?
I'm currently working on a Qt Quick application that will provide a map viewer for a smallish area (1 square KM or so), the map details for which will be provided in a single geo-referenced image file (GeoTIFF, geo-referenced PDF, ESRI Shape file etc.), along with display of current location, operator identified points of interest etc. It's primarily responsibility is the display of custom maps (as opposed to generic maps retrieved from public map image service providers (OSM, MabBox, ESRI etc)), and it will often be used in areas with limited connectivity
An extensive web search has identified others who have made similar enquiries in the past (here, Qt forums etc), and the general suggestions for solutions are as follows:
ArcGIS Runtime with Qt SDK Doesn't work for me as down the track I'm intending to target an embedded linux device using an ARM processor, and ArcGIS doesn't make source available for cross-compilation for arbitrary targets. They've recently produced an Android release, but nothing for ARM linux in general)
QGIS developer libraries GPL licence not compatible with my commercial development
Use the Qt Location Map component with a local tile server or offline tile collection (some plugins have recently introduced support for this) Seems a bit of a hack, as noted I'm primarily using custom maps, as opposed to offline copies of public map server images, and my images won't be big enough to really warrant tiling otherwise
It would be feasible to develop a Qt Quick component from scratch to do this, but given that the existing Qt Location Map component provides a well defined pre-existing front end interface for everything my map would need to do and has an extendable plugin based architecture, writing a custom Qt Location GeoServices plugin seems the most sensible and elegant way forward.
I've started examining the source code of the existing plugins, but can't shake the feeling that in a world containing 8 billion people, with "nothing new under the sun", this would have been done already if it was a good idea....
Would anyone with more familiarity with the Qt Location module care to comment?
Since geo-referenced images can be arbitrarily large, it is the standard to convert them into a tile pyramid, to be able to efficiently display them on any hardware (at the cost of doubling the size, at worst, depending on how many layers you want).
Even if you would write your own geoservice plugin, you most likely will end up (directly or by using 3rd party code) tiling your geotiff.
This said, QtLocation does allow you to use custom tilesets ( http://doc.qt.io/qt-5/location-plugin-osm.html, look for osm.mapping.custom.host) served in most ways (http, https, file, qrc, etc.).
So go ahead, fire up QGis, install the QTiler plugin, and convert your images.
If you need to serve these pictures over the net directly to the clients (thus needing to do the conversion on the client), you can either see what QTiler does, or build up your gdal pipeline (gdal_translate, gdalwarp and gdal2tiles), and ship the relevant gdal bits with your application.
If you need multiple images at the same time, you can either use multiple Plugin elements with different plugin parameters, or you can fork the osm plugin and support multiple custom hosts.
Based upon Paul's response, and a couple of similar responses to the same enquiry on Qt forums and mailing lists, plus my own investigation, I'd conclude the following:
Generating a custom Qt Location GeoServices plugin to directly provide map imagery from a geo-referenced image file would not be a great idea as the implementation would be less than straightforward, and in practice any non-trivial map image would likely be large enough that an initial tiling step, followed by use of one of the standard tiled mapping plugins referencing a local tile set would be more appropriate anyway.
Rendering large DWG files as such has shown performance degradation to large extent. Planning to use the concept of map tiles using leaflet. Need some pointers/information on how to convert DWG files to map tiles.
After too many hours, searching everywhere for a solution to convert DWG/DXF files using any automated command line tool, finally I found QCAD.org.
And that works even on Windows, MacOS and Linux.
After a quick look in documentation, I found the section for command line tools.
They are:
dwg2bmp, dwg2png, dwg2jpeg, dwg2tiff, dxf2png, dxf2jpeg, dxf2tiff
and the awesome:
dwg2maptiles and dxf2maptiles
Using this tool, they came up with a beautiful sample using leaflet.js:
http://qcad.org/res/map/
The project is OpenSource, but this scripts are only avaliable at QCAD Professional edition.
You can use the free open source QCAD Community Edition by downloading the trial version for your platform (Win, Mac, Linux) and then remove the QCAD Professional add-on running in trial mode. Alternatively, you may compile your own package from sources.
PS: I'm very happy to support the project buying a professional copy.
The easiest approach may be to save your DWG files as PDF and use MapTiler to create the raster tiles and leaflet viewer for you.
You can render such PDF by drag&drop into MapTiler while choosing the "raster" profile - just follow the video tutorial: https://youtu.be/9iYKmRsGoxg?list=PLGHe6Moaz52PiQd1mO-S9QrCjqSn1v-ay
If you need to assign coordinates for later on placing markers or polygons on specified position over the DWG tiles - it is possible with advanced tiles.
If you need help with using MapTiler - write details and provide sample file you need to process to https://www.maptiler.com/support/community/.
If you data are sensitive or you need a guarantee on the answering of your request you seek directly the support from us, the authors of MapTiler.
I'd like to take multiple video streams and display them one at a time, with the ability to swap between them. I was thinking about taking the video output from OBS and stream it to a private server using RMTP and nginx. Then I'd write some code (C/C++ maybe) to swap which stream is being displayed.
My first question is, would this even work? Would I be able to process the video being streamed to the server using this method, or would I need to send it to the server a different way? (preferably still using OBS)
My second question is, what would be a good place to get started for processing the streams? Are there any tutorials or forms that could be helpful?
I've never done any sort of video processing, so if I'm missing a key component I apologize ahead of time.
If I understand you correctly OBS gives you a couple of options to achieve this. You can create a different scene for each video input, select the scene to display the input of your choice. If you use the studio version it has a built in transition effects. Alternatively you can add all the video sources to one scene then move your desired source to the top. Using this method you can resize the sources and display more than one at a time.
Yes,upstairs is right.or you can use mimoLive.app if you are a macOS user
I've been doing some work in VB.Net with Directshow over the past 3-4 weeks. I'm creating an application to keep tags on a video and eventually want to be able to extract the tagged parts of the video to a new file. In a video that is 2 hours long I might want to extract say 50 10-15 second "clips" up to 15 times (event tagging). This will be for a free application.
I've found it brilliant (and easy) to render / seek / play clips, etc on XP-Win7 with no issues. I've "discovered" the joys of GraphEdit, creating graphs, the issues with COM in VB.NET, GMFBridge, ....etc.
Now I need some advice. Am I using the right technology. Directshow seems to be very resistant to the idea of "open video", "seek to clip", "write clip to file", .....repeat for all clips, close file. I can sort of do this already if I visibly render the video but would need to do it as a background task faster than realtime render speed.
Things that seem to be missing are:
- an example of anyone doing anything similar (export multiple clips to a single file)
- no easily available 64bit compressors (lots of 32bit stuff around)
- all the references and examples I do find are VERY old
- VB.NET is not the first "port of call" for DirectShow developers
So, the question is, should I be using something else?
If not, has anyone done anything similar before. I'm not looking for their code, I just want some guidelines as it takes ages to figure things out in DirectShow and VB.Net just using trial & error (and Google).
I've looked at AFORGE (no sound), FFMPEG (command line toolset), Media Foundation (reluctant to throw away XP) and a variety of commercial helper libraries but not really getting any further.
Apologies for the length but I wanted readers to understand the background.
All help appreciated.
To output clips to a single file Microsoft had created the "DirectShow Editing Services". Sometimes it works, sometimes not. We use it in our software to create videos from clips like you. With a little bit work you can also include effects to the video.
It is also possible to use AviSynth. It's a scripting system and frameserver for DirectShow.
As I know, with MediaFoundation you can also create a video from multiple clips, but I never tried this.