The path a stream takes
OBS encodes audio and video, sends them over RTMP or RTMPS to an ingest server, and the platform distributes versions to your viewers. In local multistream, Corneta receives one signal and opens that path for each destination.
Connection terms
RTMP
A widely used protocol for carrying audio, video and data from the encoder to the platform. It describes the transport; it is not the picture quality.
RTMPS
RTMP protected by TLS. It encrypts the leg between your encoder and the server. Always prefer it when the platform offers it.
Ingest
The server that receives your stream. The ingest URL gives the address; the stream key says which channel should receive the signal.
Stream key
The secret that authorizes the broadcast. Treat it like a password: don't show it in screenshots, videos, logs or diagnostics.
Picture terms
Resolution
The number of pixels in the frame, such as 1280×720 or 1920×1080. More pixels only turn into more detail when bitrate and encoder keep up.
FPS
Frames per second. 60 FPS makes motion smoother, but doubles the volume of frames compared with 30 FPS.
Bitrate
The amount of data sent per second. In live streaming, it usually shows up in kbps or Mbps. Adding up output bitrates helps estimate upload; on its own, it doesn't measure the final quality.
Keyframe
A complete frame used as a reference point. Between keyframes, the encoder describes changes. Twitch, YouTube and Kick usually work with a 2-second interval.
CBR
Rate control that tries to keep the bitrate constant. It's the default recommended by the major platforms for live ingest.
Processing terms
Encoder
Turns frames and audio into a compressed stream. It can use the CPU, like x264, or dedicated hardware, like NVENC, QSV and AMF.
Codec
The compression standard the encoder uses, such as H.264, HEVC or AV1. The encoder does the work; the codec is the format of that work.
Copy or passthrough
Copies the already encoded stream without recreating the video. Saves CPU and GPU, but keeps the resolution, FPS, bitrate and orientation it received.
Transcode
Decodes and encodes another version. Lets you change resolution, FPS, bitrate or framing, but costs processing power and can lose quality.
Relay
An intermediary that receives a stream and forwards it somewhere else. It can be local, like Corneta, or in the cloud, like restream services.
Diagnostic terms
Dropped frames
Frames that didn't reach the destination because of a network problem. In OBS, don't confuse them with frames skipped because of rendering or encoding.
Render lag
OBS couldn't build the frames in time, usually because of a lack of GPU resources or a heavy scene.
Encoding lag
The encoder didn't finish the frames in time. It can point to CPU, GPU, preset or too many sessions.
When a counter gets worse, use the dropped frames, rendering and encoding decision tree before you change everything at once.