# SRT to WHEP This application ingests one MPEG-TS over SRT stream and outputs to WebRTC recvonly clients using WHEP as signaling protocol. Example of use cases: - Browser based confidence monitor of an incoming stream - Program or preview output monitor in a browser or tablet Supports SRT streams in caller and listener mode. Runs on MacOS and Ubuntu. ![screenshot](docs/screenshot.png) ## Design Principles When conceiving this project, we made deliberate design choices to shape its functionality and behavior in alignment with our vision: - No Video Transcoding: We have intentionally refrained from implementing video transcoding within this component. This decision stems from the desire to maintain the integrity of the original video stream. This approach caters to use cases like confidence monitoring or preview. If you wish to transcode video anyway, here is an [example](https://github.com/Eyevinn/srt-whep/issues/36#issuecomment-1667880628) to do that. - Server-Side Initiation Mode: Our project does not currently support the client-side initiation mode of [WebRTC-HTTP Egress Protocol (WHEP)](./docs/whep.md). Instead, we have adopted a server-side initiation approach. In this mode, the server provides the SDP offer, as it possesses knowledge of the available streams. - Focus on SDP Offer/Answer Exchange: Our server's primary focus is on the exchange of SDP (Session Description Protocol) offers and answers. While WebRTC typically involves ICE (Interactive Connectivity Establishment) negotiation for establishing peer-to-peer connections, we have opted not to include ICE negotiation within the scope of our project at this time. Our emphasis remains on the effective exchange of SDP-related information. ## Compliance Table Here we have a list of supported production software. | Source Type | Supported | Details | |-------------------|----------------------|------------------------------------------| | FFMpeg | :white_check_mark: | A complete, cross-platform solution to record, convert and stream audio and video | | [OBS](https://obsproject.com) | :white_check_mark: | Free and open source software for video recording and live streaming | | GStreamer | :white_check_mark: | A pipeline-based multimedia framework | | [Agile Live](https://docs.agilecontent.com/docs/acl/) | :white_check_mark: | A software-based platform for production of media using standard, off-the-shelf hardware and datacenter building blocks. | | [Intinor Direkt](https://intinor.com/) | :white_check_mark: | Intinor Direkt series is a product line of encoders and decoders for live video over the internet. | ## Getting Started It is suggested that - Mac Users: Follow our comprehensive build instructions and use Chrome for streaming. - Ubuntu Users: Either build the program from source or use Docker for running. Both methods are supported. Some useful commands can be found [here](./docs/useful_commands.md). ## Install ``` cargo install srt_whep # recommended for pretty log viewer (optional) cargo install bunyan ``` Generate an SRT test source for example using our testsrc Docker container: ``` docker run --rm -p 1234:1234/udp eyevinntechnology/testsrc ``` An SRT stream (in listener mode) is then available at `srt://127.0.0.1:1234`. Then run the `srt-whep` application: ``` srt-whep -i 127.0.0.1:1234 -o 127.0.0.1:8888 -p 8000 -s caller | bunyan ``` It will connect to the SRT test stream in caller mode as the generated SRT stream is in listener mode. WHEP endpoint is available at `http://localhost:8000/channel`. You can then play it for example using the WHEP [Player](https://webrtc.player.eyevinn.technology/?type=whep). Possible issues are discussed in [Issues](#issues). If you don't have Rust install you can use the Docker Container image published on Docker Hub: ``` docker run --rm --network host eyevinntechnology/srt-whep \ -i 127.0.0.1:1234 \ -o 0.0.0.0:8888 \ -p 8000 -s caller ``` Note that the container needs to run in host-mode (supported only on Linux). ## Build from Source ### OSX Requirements: - XCode command line tools installed - GStreamer [binaries](https://gstreamer.freedesktop.org/data/pkg/osx/) from GStreamer's website installed - Rust and cargo installed Make sure you have the following env variables defined: ``` export PATH=$PATH:/Library/Frameworks/GStreamer.framework/Versions/Current/bin export PKG_CONFIG_PATH=/Library/Frameworks/GStreamer.framework/Versions/Current/lib/pkgconfig export GST_PLUGIN_PATH=/Library/Frameworks/GStreamer.framework/Versions/Current/lib export DYLD_FALLBACK_LIBRARY_PATH=$GST_PLUGIN_PATH ``` Build with Cargo ``` cargo check cargo install bunyan # Optional, for pretty printing of logs cargo build --release ``` The binary is then available at `./target/release/srt-whep`. See below for how to run it. ### Debian (bullseye / bookworm) Requirements: - Rust and cargo installed Install GStreamer build dependencies. ``` apt-get update apt-get -y install build-essential \ curl \ pkg-config \ libssl-dev \ libunwind-dev \ libgstreamer1.0-dev \ libgstreamer-plugins-base1.0-dev \ libgstreamer-plugins-bad1.0-dev \ gstreamer1.0-plugins-base \ gstreamer1.0-plugins-good \ gstreamer1.0-plugins-bad \ gstreamer1.0-plugins-ugly \ gstreamer1.0-libav \ gstreamer1.0-tools \ gstreamer1.0-x \ gstreamer1.0-alsa \ gstreamer1.0-gl \ gstreamer1.0-gtk3 \ gstreamer1.0-qt5 \ gstreamer1.0-pulseaudio \ gstreamer1.0-nice ``` Build with Cargo ``` cargo check cargo install bunyan # Optional, for pretty printing of logs cargo build --release ``` The binary is then available at `./target/release/srt-whep`. See below for how to run it. ## Docker Container Build container (uses multi-stage builds): ``` docker build -t srt-whep:dev . ``` Container must be running in host-mode (only works on Linux hosts, and is not supported on Docker Desktop for Mac, Docker Desktop for Windows) ``` docker run --rm --network host srt-whep:dev \ -i : \ -o 0.0.0.0:8888 \ -p 8000 -s caller ``` ## Usage To ingest an SRT stream with address `srt://127.0.0.1:1234` in listener mode and expose WHEP endpoint on port 8000 run the application with this command. ``` cargo run --release -- -i 127.0.0.1:1234 -o 127.0.0.1:8888 -p 8000 -s caller | bunyan ``` This will also make a pass-through of the SRT stream on `srt://127.0.0.1:8888` in listener mode. To watch the pass-through stream in ffplay, VLC or GStreamer you run: ``` ffplay srt://127.0.0.1:8888 # or gst-launch-1.0 playbin uri="srt://127.0.0.1:8888" ``` WHEP endpoint is available then at `http://localhost:8000/channel`. You can then play it for example using the WHEP [Player](https://webrtc.player.eyevinn.technology/?type=whep). If the SRT stream to ingest is in caller mode you run the application with this command. ``` cargo run --release -- -i 127.0.0.1:1234 -o 127.0.0.1:8888 -p 8000 -s listener | bunyan ``` This also expects the SRT address `127.0.0.1:8888` to be running in caller mode. ## Tips for Successful Streaming When working with SRT streams, there are several important considerations that can affect the success of your streaming experience: 1. **Stream Generation and Playback Tools:** - Different tools, such as FFMpeg, GStreamer, FFPlay, and VLC, can be used to generate and play SRT streams. We've tested our program with these tools, so you can choose the one that suits your needs. - Be aware of the mode option in the SRT stream configuration, which can be set as `caller`, `listener`, or `rendezvous`. This option determines the behavior of the stream, and it needs to be configured correctly for successful streaming. 2. **Bitrate Parameter in FFMpeg Streams:** - When generating streams using FFMpeg, it's essential to specify the Bitrate parameter. Failing to do so might result in VLC/GStreamer being unable to play the stream. 3. **Video Codecs and Profiles:** - WebRTC connection failures can often be attributed to incompatible video codecs. While we strive to support both H.264 (AVC) and H.265 (HEVC) streams, it's important to note that most mainstream browsers only support AVC for WebRTC. - Safari, which is the only browser supporting H.265, has its own RTP payload format and custom video profile requirements, different from the standard ([RFC 7798](https://www.rfc-editor.org/rfc/rfc7798.html)). So it does not work directly out of box. There is a [PR](https://github.com/WebKit/WebKit/pull/15494) available for fixing this H265 packetization issue in WebKit project but no one is viewing it for the moment. - Based on the [discussion](https://github.com/AlexxIT/Blog/issues/5), it seems rather challenging to support H.265 / HEVC right now. 4. **Codecs and Profiles Compatibility:** - Video profiles, such as Baseline, Main, and High for H.264, play a crucial role in stream compatibility. While Chrome supports all profiles, Safari only accepts the Baseline profile. For further details, please refer to [this](./docs/supported_codecs.md) table. 5. **SRT Stream Latency:** - SRT streams can be configured to have different latencies. For example, if you're using GStreamer to generate SRT streams, you can set the latency parameter of `srtsink` or `srtsrc` to fit your need. For example, `latency=200` sets the latency to 200ms, which is appropriate for most use cases. - Our tool adds a minimun latency to the stream by default. If you want to measure the end-to-end latency, you can try to generate a stream using OBS with a clock overlay (which adds a very low latency). Then you can compare the clock in the stream with the built-in clock from our WHEP player. The end-to-end latency should be around 300~500 ms. ## Discussion and Issues All relevant discussions are tracked in [issues](https://github.com/Eyevinn/srt-whep/issues/). Please feel free to open a new issue if you have any questions. - We have a set of known limitations recorded [here](./docs/known_limitations.md). You might want to check it out if running into an issue. - If you doubt a plugin is missing in gstreamer you can check it using `gst-inspect-1.0 `. For example, `gst-inspect-1.0 srtsink`. - To get more verbose logging you can set the `GST_DEBUG` environment variable to `2`. For example, run in terminal: `export GST_DEBUG=2` ## License (Apache-2.0) Copyright 2023 Eyevinn Technology AB Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ## Support Join our [community on Slack](http://slack.streamingtech.se) where you can post any questions regarding any of our open source projects. Eyevinn's consulting business can also offer you: - Further development of this component - Customization and integration of this component into your platform - Support and maintenance agreement Contact [sales@eyevinn.se](mailto:sales@eyevinn.se) if you are interested. ## About Eyevinn Technology Eyevinn Technology is an independent consultant firm specialized in video and streaming. Independent in a way that we are not commercially tied to any platform or technology vendor. At Eyevinn, every software developer consultant has a dedicated budget reserved for open source development and contribution to the open source community. This give us room for innovation, team building and personal competence development. And also gives us as a company a way to contribute back to the open source community. Want to know more about Eyevinn and how it is to work here. Contact us at work@eyevinn.se!