What’s the problem?
One of the powerful things you can do with the internet nowadays is access web cameras and video sources from around the globe. Over the last 5+ years the team here at Webmad have been hosting web camera re-streaming services for https://taylorssurf.co.nz. The site runs a few IP cameras based at a local surf and recreation beach here in Christchurch, New Zealand. Since starting with this site, we’ve managed a number of different methods of getting the video from the various cameras, and for various clients as well.
So the problem we are trying to solve is how do we get the video from the cameras out to viewers on the internet so that hundreds of people can view the video streams at once. Typically a camera has a limit of around 20 connected users at a time if you are trying to access the camera directly, and if your camera is on a fairly limited bandwidth internet connection (at Taylors Mistake we can only get VDSL speeds at best) then multiple people trying to access the cameras at once will kill the streams pretty quickly. The other issue is that the default streams from the cameras we’ve got there are not in overly friendly formats for websites (rtsp etc) meaning you’d have to use flash based video players, which pretty much all web browsers look down on these days.
So… What can we do?
In New Zealand, ISP’s don’t charge for internet traffic between two endpoints within their networks. This is fantastic as it means there is no charge for bandwidth between the cameras at remote locations and our re-streaming server we host locally, provided we use the same internet provider. This allows us to cost effectively re-stream the video, meaning there is only one connection to each camera pulling in video feeds, and that can then re-broadcast the camera feeds on a high capacity internet connection allowing thousands of end users to connect to view the video images.
Solution 1: The mjpeg streamer
On cameras that only output an mjpeg stream, we developed the mjpeg-streamer. Basically what it does is it connects to the camera source, and then feeds that into a memory buffer. Then any consecutive requests to the script, instead of fetching the camera feed from the camera, will connect to that same memory buffer and return the camera feed to the end user as an mjpeg stream. By using php tools like imagemagick you can add image overlays onto the stream as needed. This system works really well so long as you have difference memory locations for each different camera you are looking to re-stream, and requires low resource usage on the server side, so it can be easily used on shared hosting. The downsides of using this type of streaming is that there is no ability to alter resolution easily, and mjpeg streams have questionable capability with most modern browsers, and have been known to crash browsers that can’t clear older frames from the video from their memory.
Solution 2: The RTSP / RTMP re-streamer
A camera upgrade eliminated our ability to use mjpeg streaming, so we were forced to update our streaming strategy. The best tools for the job came in the form of the open source Red5 flash streaming server and the open source FFMPEG application. The aim here is to use ffmpeg to pull the video from the camera, and feed it to the red5 flash streaming server. Clients must then use a flash based player to connect to red5 and play the video stream. This works well, and any overlays can be injected during the ffmpeg based ingest process. The code is at https://github.com/stephen-webmad/rtsp-restream
Where this falls over is that modern browsers no longer support flash based players. So, we had to move to something else.
Solution 3: HTTP live streaming
Remember how we are using ffmpeg in the solutioni above? Well – turns out there is another format it can output, HLS (HTTP Live Stream). What is HLS? It’s a sequence of bite sized chunks of the video stream, all tied together using an index file. Where HLS comes out tops for live streaming is that it enables you to pause and rewind the live stream, allowing you to go back as many chunks as are stored in the index, which can be real handy. The index file can be as big as you want. The player just polls the index file (checks in on it every few seconds) to see if there are any new video chunks to download, and grabs them if there are. You can see this in action at https://canview.nz
HLS is super handy for web browsers and mobile as its easily playable, and you only need to fetch small chunks of video, meaning page load times as measured by Google etc are typically much better. The downside of HLS streaming is that your live stream will be delayed a little as it needs to build up the video chunks for the players to download, but for most things, that is an acceptable compromise. For most of our video streams this is around the 30 second delay sort of mark, but this can be shortened by tweaking the settings.
We’ve not yet created a git repository outlining how we operate this form of live streaming – this is likely to come in the future, but for now, if you are looking to live stream a web camera from anywhere in New Zealand, or the world if you have friendly international traffic allowances, do please contact us and we can help make that happen, or if you’ve got the resources, we can assist with getting you all set up to run it yourself.