LiveKit Encoder Comparison

A Rust-based screen sharing application for testing and comparing different video codecs with LiveKit.

Prerequisites

• Rust (latest stable version)
• Cargo
• LiveKit server instance
• LiveKit access token

Environment Setup

Before running the screen_sharer, you need to set the following environment variables:

export LIVEKIT_URL="your_livekit_server_url"
export LIVEKIT_TOKEN="your_livekit_access_token"

Important: When testing both the screen_sharer and client together, ensure that both tokens are created for the same LiveKit room. You can generate tokens using the LiveKit CLI or programmatically using the LiveKit SDK.

Screen Sharer

The screen_sharer application captures your screen and streams it to a LiveKit room with configurable video encoding parameters.

Building

The encoder uses a LiveKit Rust SDK fork that exposes libwebrtc's DesktopCapturer. Before building the screen_sharer, you need to:

1. Build the updated libwebrtc library from our fork (which contains our patches)
2. Point to it using the LK_CUSTOM_WEBRTC environment variable

You can find instructions for building the custom libwebrtc in the LiveKit Rust SDK documentation.

Once the custom libwebrtc is built, navigate to the screen_sharer directory and build the application:

export LK_CUSTOM_WEBRTC="/path/to/your/custom/libwebrtc"
cd screen_sharer
cargo build --release

Running

Basic usage:

cargo run

Command Line Options

The screen_sharer supports various configuration options:

Option	Short	Description	Default	Available Values
--resolution	-r	Screen resolution	1080p	720p, 1080p, 1440p
--duration	-d	Recording duration in seconds	60	Any positive integer
--codec	-c	Video codec	VP9	VP8, VP9, H264, AV1
--bitrate	-b	Bitrate in kbps	4000	Any positive integer
--source	-s	Screen source index	0	Any valid screen index
--fps	-f	Frames per second	30	Any positive integer
--name	-n	Name for log file	test	Any string
--simulcast		Enable simulcast	false	Flag (no value needed)

Examples

Basic screen sharing with default settings:

cargo run

Record in 1440p with H264 codec for 2 minutes:

cargo run -- --resolution 1440p --codec H264 --duration 120

High bitrate VP9 encoding with simulcast:

cargo run -- --codec VP9 --bitrate 8000 --simulcast --name high_quality_test

AV1 encoding test:

cargo run -- --codec AV1 --bitrate 2000 --duration 180 --name av1_test

Output

The application will:

1. Connect to the specified LiveKit room
2. Start screen capture and streaming
3. Display configuration information
4. Generate CSV files with performance metrics
5. Save logs with the specified name

Generated files include CPU usage data and encoding performance metrics saved in the screen_sharer directory.

Client Application

The client application is designed to measure end-to-end latency by connecting to LiveKit rooms and receiving video streams. Unlike the screen_sharer, the client uses the standard LiveKit Rust SDK and doesn't require the custom fork.

Building the Client

Navigate to the client directory and build:

cd client
cargo build --release

Running the Client

The client requires the same environment variables as the screen_sharer:

export LIVEKIT_URL="your_livekit_server_url"
export LIVEKIT_TOKEN="your_livekit_access_token"

Run the client with an output file for latency measurements:

cargo run -- --output-file latency_results.csv

Command Line Options

Option	Short	Description	Required
--output-file	-o	Output file path for latency measurements	Yes

Usage Example

To measure end-to-end latency during a screen sharing session:

1. Start the screen_sharer in one terminal:

cd screen_sharer
cargo run -- --codec VP9 --duration 300 --name latency_test

2. Start the client in another terminal:

cd client
cargo run -- --output-file latency_vp9_test.csv

The client will automatically connect to the same LiveKit room and begin measuring latency as soon as it receives video frames from the screen_sharer.