Proposal: WebSocket video streaming with MPEG1 transcoding (support H265) using go-astiav (CGO / FFmpeg)

[LongND0105]

Hi author,

I’d like to share a feature I’ve recently implemented while working with lkmio/lkm, and ask whether it would be appropriate to contribute it via a Pull Request.

What I’ve implemented

I added a new video streaming path that:

• Streams video over WebSocket
• Transcodes the input stream to mpeg1video in real time
• Pushes the output as MPEG-TS packets to connected WebSocket clients

Technical details

• The transcoding pipeline is implemented using CGO bindings via go-astiav
• FFmpeg components used include:
  • libavformat
  • libavcodec
  • libavutil
• Decoding, filtering (if needed), and encoding are handled directly through FFmpeg APIs exposed by go-astiav
• No external ffmpeg binary process is spawned; everything runs in-process via CGO

This design keeps the implementation:

• Consistent with existing FFmpeg-based logic in the project
• Efficient for real-time streaming
• Easier to extend for other codecs or transports in the future

Use cases

• Low-latency video preview
• Browser-based playback using WebSocket players (e.g. jsmpeg-like clients)
• Debugging / monitoring live video streams without HLS/DASH

Backward compatibility

• The new WebSocket streaming path is isolated and does not affect existing APIs or streaming flows

Next step

Before preparing a Pull Request, I’d like to ask: Would you be open to accepting a PR for this feature?

If so, I’m happy to:

• Refactor or simplify the code if needed
• Align with project conventions
• Add documentation or example usage

Thanks for your time, and I look forward to your feedback.

[ydajiang]

it's great!
I am looking forward to your pr very much. I will create a new branch called "feature/transcode" for this new feature.

My previous idea for video transcoding was to enable transcoding in the HTTP hook publish event. The transcoding service uses the RTMP protocol to pull the stream from LKM and then transcode it. Finally, the original codec's pull address and the generated codec's pull address are merged together.

Welcome to communicate. The LKM project is still in its early stages and is very open.

[ydajiang]

Very good. Implement it according to your idea, using LKM for transcoding. This will achieve both the original LKM streaming service and the LKM transcoding service.