Plain-English explanations of the technical words you'll meet. You don't need to know any of this to use Cosmik Streamer — it's here for when you're curious, or when a client asks for something by name.
Air unit
The video transmitter on your drone (a DJI O3 or O4 Air Unit Pro). It films, records to its own memory card, and beams the picture to your goggles.
Aspect ratio
The shape of the picture. 16:9 is widescreen (TVs, YouTube). 4:3 is taller — many pilots prefer it for flying because you see more ground and sky.
Bitrate
How much data the video uses per second, in megabits per second (Mb/s). More data generally means better quality but needs a stronger connection. If viewers report stuttering, lower this first.
Broadcast version / broadcast branch
A second copy of your flight that Cosmik Streamer creates — reshaped and branded for an audience — while your own view stays untouched.
Codec / H.264
The method used to squeeze video down small enough to send. H.264 is the most widely supported one; virtually every device can play it.
Crop
Filling the screen by trimming the edges off the picture. No black bars, but you lose a little from the sides or top and bottom. Opposite of Pad.
CSV
A simple spreadsheet file. Opens in Excel, Numbers, or Google Sheets. Cosmik Streamer uses one for the clip shot list.
ELRS (ExpressLRS)
A popular open-source radio control system. If you fly with a RadioMaster Boxer or similar, that's ELRS. It's what provides the signal readings.
FPS (frames per second)
How many pictures per second make up the video. Higher is smoother. 30 and 60 are common.
Gyro data / stabilisation
Your drone records how it moved — tilts, shakes, rotations — alongside the video. Software like GyroFlow uses that motion record to remove the shake afterwards, producing very smooth footage. It only works if the motion data was recorded in the first place — see the note in Media & Clip Requests.
Buffer (rolling clip buffer)
The last ten minutes of your live feed, held in the Streamer's memory. It is not a recording — it writes over itself constantly, so everything older than ten minutes is gone for good. Saving a clip out of it is coming soon and is not built yet, so today nothing comes back out of the buffer: only what you Record is kept. It is switched off until you turn it on, and you choose whether it lives in the Streamer's memory or on the memory card. See Media & Clip Requests.
Hardware encoding (HW)
Letting a dedicated chip do the heavy video work instead of the general processor. It's why Cosmik Streamer can produce a branded broadcast version without slowing your live picture.
HLS
A broadly compatible way of sending video, including to many smart TVs. It adds more delay than WebRTC, so it is a fallback rather than the first choice for a live view.
Latency / delay
How far behind real life the picture is. The pilot feed is passed through untouched to keep this as small as possible; the branded broadcast version is re-encoded, so it always runs a little further behind. We don't publish a figure for either yet.
Link Quality (LQ)
The percentage of radio signals successfully getting through between your radio and drone. 100% is perfect. Falling LQ means you're approaching the limit of your range.
Lower-third
A name bar across the bottom of the screen — like the caption under someone being interviewed on TV.
MPEG-TS
A way of sending video directly to another machine on a network. Used in professional outside-broadcast setups.
NDI
A studio standard for sending video between machines on a production network. Coming soon.
Pad / letterbox / pillarbox
Keeping the whole picture and filling the leftover space with black bars. Nothing is lost. Opposite of Crop.
Passthrough
Sending the video onward completely untouched — not re-processed. It's why the pilot feed stays fast and keeps its original quality.
Pilot feed
The live picture exactly as you see it, untouched and as fast as possible.
RSSI
Signal strength, measured in dBm. Always a negative number, and closer to zero is stronger — −40 is excellent, −100 is weak.
RTMP / RTMPS
The format YouTube, Facebook and Twitch use to receive live video. You paste in an address and a stream key. RTMPS is the encrypted version.
RTSP
A video address that some production gear can connect to directly. The link itself is fast — it is the player that usually buffers a few seconds before showing anything, and most players let you turn that buffer down. For OBS and vMix the browser address is still the easier first choice (OBS & Production Tools).
SNR (signal-to-noise ratio)
How clearly your signal stands out from background interference. Higher is better.
SRT
A broadcast-industry format designed to keep video intact over unreliable internet. If a client asks for SRT, they'll give you an address to paste in.
Stream key
A long password-like code from YouTube, Facebook or Twitch that identifies your channel. Keep it private — anyone with it can broadcast to your channel.
Telemetry
Live information from your radio and your aircraft. Signal strength comes from the radio and works as soon as it connects. Battery, position and altitude come from the aircraft's own flight controller, so they appear only if it is set up to send them — and position needs a GPS module fitted. See Signal & Telemetry.
Timecode
A running clock burned into the picture, so you and a client can refer to the exact same moment without ambiguity.
TX power
How hard your radio transmits, in milliwatts (mW). More power reaches further but drains the battery faster.
WebRTC
The technology behind the fast live view. It's what video-calling uses, which is why it's so quick. This is the link to send people who just want to watch.
Source: /docs/glossary.md