In the world of digital entertainment, live streaming has taken center stage, revolutionizing how we consume content.

Have you ever wondered what happens behind the scenes to ensure a seamless and immersive livestreaming experience? Let's dive into the system design of a live-streaming application! 👇

The journey to your screens starts with capturing the digital video and audio. Key considerations here include:

1. Encoding and Compression: Choosing the right video and audio codecs is crucial for efficient compression quality. H.264 for video and Advanced Audio Coding (AAC) for audio are the popular choices.

2. Real-Time Messaging Protocol (RTMP): RTMP helps transmit data further between the services. It sits on top of TCP and ensures reliable and real-time delivery of video and audio stream allowing for low-latency communication between the source and the processing servers.

3. Transcoding and packaging: The content then goes through transcoding and packaging. This process involves converting the encoded content into multiple bit-rate and resolution renditions. Why do we need this? See below.

   1. Resolutions: Live streams need to cater to a wide range of devices and network conditions. Adaptive streaming techniques enable us to dynamically adjust resolutions, from 360p to 4k, to provide the best quality for each viewer.

   2. Adaptive-bitrate(ABR): ABR ensures a seamless viewing experience by dynamically adjusting the bitrate based on network conditions. This ensures that viewers with varying internet speeds can enjoy the stream without the buffering issues.

Hence multiple versions of the video stream need to be generated to support the combination of resolution and supported bit rate streaming protocol. For instance, you might have renditions at 1080 p with bitrates ranging from 5Mbps to 1Mbps.

1. Content delivery: The next step is to distribute the content efficiently to the end users' devices. The requested content from the player can be served through protocols like HLS (HTTP live streaming) and DASH (Dynamic Adaptive Streaming over HTTP) that support ABR for efficient delivery. A content delivery network (CDN) can be used to further ensure low-latency streams.

2. Player: On the users' end, the player logic is responsible for selecting the appropriate stream based on network conditions and device capabilities. It seamlessly switches between different renditions to maintain the best possible quality.

Conclusion: The system design behind a live-streaming application lies in the careful orchestration of codecs, resolutions, adaptive bitrate technologies, and streaming protocols like RTMP, HLS, and DASH.