Package ascii converts raw video frames into truecolor terminal art.
Each character cell renders two vertical pixels using the upper-half block
(▀): foreground colors the top pixel, background the bottom — the same
technique doom-ascii uses. A WxH terminal therefore displays a Wx(2H)
pixel image.
FrameRGB renders a packed RGB24 frame (w*h*3 bytes, as ffmpeg's rawvideo
rgb24 emits) sized exactly for the target cell grid: w columns, h*2 rows
of pixels. Rows are joined with \r\n so the output is PTY-safe.