/webrtc-snapshot-example

This is example code for connecting to a WebRTC WHEP endpoint and saving an incoming frame to file

Primary LanguageC#

WebRTC Snapshot Example

This is some example code for connecting to a WHEP endpoint and saving a snapshot of a frame, written in C# using .NET 8. It was written to be used in connection with Broadcast Box, but could be repurposed for any other WHEP endpoint.

Run this locally

To run this locally you will be required to make some changes to this program to target the correct OS, FFMPEG library, and stream.

Clone

Clone this repo and navigate to the program directory

git clone https://github.com/richardtatum/webrtc-snapshot-example.git webrtc-snapshot-example
cd webrtc-snapshot-example/Snapshot

Update variables

Update the url, streamKey, imageFileName and ffmpegLibLocation variables as required

# Program.cs
- var url = "https://b.siobud.com/api/whep"; 
+ var url = "https://hosted.broadcast.box/api/whep";

- var streamKey = "stream-key";
+ var streamKey = "richard-test";

- var imageFileName = $"/path/to/frame-{streamKey}.jpg"
+ var imageFileName = $"/home/rt/Pictures/snapshot/frame-{streamKey}.jpg"

- var ffmpegLibLocation = "/usr/lib64";
+ var ffmpegLibLocation = "/usr/lib/x86_64-linux-gnu";

Run

You can then run the program with dotnet run:

dotnet run

After starting, if everything is setup correctly, you will see an output similar to the following:

[PROGRAM] Connecting to WHEP endpoint...
[CONNECTION] Answer received
[CONNECTION] ICE state changed: checking
[CONNECTION] Remote description set. Response: OK
[PROGRAM] Press any key to exit...
[CONNECTION] ICE state changed: connected
[CONNECTION] State changed: connecting
[CONNECTION] State changed: connected

You can then start your stream through OBS/streaming software of choice, ensuring that the provided stream key matches the one setup in Update Variables:

[STREAM] Frame received. Size: 2024x848 Format: Rgb
[PROGRAM] Frame saved to file. Path: /home/rt/Pictures/snapshot/frame-richard-test.jpg

By default, this will continue to override the image every 30 seconds:

[TIMER] Snapshot timer reset.
[STREAM] Frame received. Size: 2024x848 Format: Rgb
[PROGRAM] Frame saved to file. Path: /home/rt/Pictures/snapshot/frame-richard-test.jpg

Troubleshooting

Below are some troubleshooting steps that may help if you have issues

  • If the stream does not connect, ensure the url and key are set correctly
  • If the SDP offer is rejected, it is possible you have set an incorrect VideoCodec for the endpoint in question
  • If FFMPEG cannot be initialised, make sure you are not setting it as the location of the executable, but the libs. For Arch linux ffmpeg lives at /sbin/ffmpeg but the lib is at /usr/lib64
  • If you are using Windows or MacOS and can't get FFMPEG initialised, check the issues over at SIPSorceryMedia.FFMPEG
  • If the saved image quality is poor, you can increase it by setting the Quality config variable in SaveFrameToFile > image.SaveAsJpeg. This is line 155 by default.