Stream live video from Raspberry Pi Camera to Android App - amazon-s3

Question

I have multiple Raspberry Pi Devices with the native camera in my home and office (PUBLISHERS). - Publisher(Pi) they are on a local network behind a firewall/router and connected to the internet.
I have an EC2 webserver (BROKER). It is publicly accessible over a public IP Address.
I have an Android App on my phone. It has internet connectivity through a 4G Network. (SUBSCRIBER/CONSUMER/CLIENT)
I am trying to view the live feed of each of the raspberry cameras on my Android app. The problem is more conceptual than technical. I am unable to decide what should be the right approach and most efficient way to achieve this in terms of costs and latency.
Approaches, I have figured out based on my research on this:-
Approach 1:
1. Stream the camera in RTSP / RTMP in the pi device via raspvid/ffmpeg
2. Have a code in the pi device that reads the RTSP stream saves it to AWS S3
3. Have a middleware that transcodes the RTSP stream and saves it in a format accessible to mobile app via S3 url
Approach 2:
1. Stream the camera in RTSP / RTMP in the pi device via raspvid/ffmpeg
2. Have a code in the pi device that reads the RTSP stream pushes it to a remote frame gathering (ImageZMQ) server. EC2 can be used here.
3. Have a middleware that transcodes the frames to an RTSP stream and saves it in a format on S3 that is accessible to the mobile app via pubicly accessible S3 URL
Approach 3:
1. Stream the camera in WebRTC format by launching a web browser.
2. Send the stream to a media server like Kurento. EC2 can be used here.
3. Generate a unique webrtc pubicly accessible url to each stream
4. Access the webrtc video via mobile app
Approach 4:
1. Stream the camera in RTSP / RTMP in the pi device via raspvid/ffmpeg
2. Grab the stream via Amazon Kinesis client installed on the devices.
3. Publish the Kinesis stream to AWS Cloud
4. Have a Lambda store to transcode it and store it in S3
5. Have the mobile app access the video stream via publicly accessible S3 url
Approach 5: - (Fairly complex involving STUN/TURN Servers to bypass NAT)
1. Stream the camera in RTSP / RTMP in the pi device via raspvid/ffmpeg
2. Grab the stream and send it a to mediaserver like gstreamer. EC2 can be used here.
3. Use a live555 proxy or ngnix RTMP module. EC2 can be used here.
4. Generate a unique publicly accessible link for each device but running on the same port
5. Have the mobile app access the video stream via the device link
I am open to any video format as long as I am not using any third-party commercial solution like wowza, antmedia, dataplicity, aws kinesis. The most important constraint I have is all my devices are headless and I can only access them via ssh. As such I excluded any such option that involves manual setup or interacting with desktop interface of the PUBLISHERS(Pis). I can create scripts to automate all of this.
End goal is I wish to have public urls for each of Raspberry PI cams but all running on the same socket/port number like this:-
rtsp://cam1-frontdesk.mycompany.com:554/
rtsp://cam2-backoffice.mycompany.com:554/
rtsp://cam3-home.mycompany.com:554/
rtsp://cam4-club.mycompany.com:554/

Answer 1

Basically, with raspvid/ffmpeg you have a simple IP camera. So any architecture applicable in this case would work for you. As example, take a look at this architecture where you install Nimble Streamer on your AWS machine, then process that stream there and get URL for playback (HLS or any other suitable protocol). That URL can be played in any hardware/software player upon your choice and be inserted into any web player as well.
So it's your Approach 3 which HLS instead of WerRTC.

Answer 2

Which solution is appropriate depends mostly on whether you're viewing the video in a native application (e.g. VLC) and what you mean by "live" -- typically, "live streaming" uses HLS, which typically adds at least 5 and often closer to 30 seconds of latency as it downloads and plays sequences of short video files.
If you can tolerate the latency, HLS is the simplest solution.
If you want something real-time (< 0.300 seconds of latency) and are viewing the video via a native app, RTSP is the simplest solution.
If you would like something real-time and would like to view it in the web browser, Broadway.js, Media Source Extensions (MSE), and WebRTC are the three available solutions. Broadway.js is limited to H.264 Baseline, and only performs decently with GPU-accelerated canvas support -- not supported on all browsers. MSE is likewise not supported on all browsers. WebRTC has the best support, but is also the most complex of the three.
For real-time video from a Raspberry Pi that works in any browser, take a look at Alohacam.io (full disclosure: I am the author).