How it works
Editing cues
Open a video and an SRT or VTT file, or start empty. Each cue has text, a start and an end. Times accept 1:02.5, 00:01:02,500 or plain seconds. The number beside a cue jumps the video to it, and the plus button adds a cue at the playhead that ends before the next cue begins.
The caption shows over the picture as you play or scrub, drawn the same way it will be burnt, so what you see is what you get.
Burning in
Burning decodes the video frame by frame, paints the caption on every frame where a cue is showing, and encodes the result with WebCodecs into MP4 or WebM. Audio is kept. The choice of encoder depends on what your browser can encode at the video's size: H.264 is the safest for sharing.
Because the video is encoded again, quality depends on the bitrate, which is set from the frame size and rate.
bitrate ≈ width × height × frames per second × 0.12, kept between 1 and 40 Mb/s
