Overlay on a webcast
The names, the laps and the clock over the camera picture: TABLEAU draws on a green background that the production software removes, and delays its display to stay in sync with a video that arrives late.
Example: the Coupe Hollywood streamed live on the Internet. The ECRAN-VIDEO computer has two screens: the first, in full screen, is captured by the video mixer; the second holds the control panel.
- The screen background, green “#00FF00”: everything green disappears.
- Two cards at the bottom of the picture: starting colour, name, last lap, cumulative; backgrounds at 80% opacity.
- The race clock, in the banner, placed at the bottom right.
1. The overlay view
- The green background
Duplicate the default view. View tab: Screen background “#00FF00” (in the ▾ palette).
- The cards at the bottom
Banner height 860: the cards start at 866 pixels, in the bottom fifth of the picture; Row height 70, Bottom margin 0. With a race in pairs, two lines. Remove what clutters (avatar, team).
- See the track through
On the name, the last lap and the cumulative: Background opacity (%) 80. Only the background becomes transparent: the text stays solid and sharp. Avoid green in the elements.
- The clock
“Race timer” in the banner, at Offset X 1610, Offset Y 866 (banner elements can be placed anywhere on the screen). The top banner stays empty: no “Competition” or “Current time”.
TABLEAU's text is smoothed in greyscale: once the green is removed, there are no coloured fringes around the letters.
2. The computer
- The panel on the second screen
Detach: the panel moves into its own window; put it on the second screen. Nothing you do there appears in the video, and closing it only hides it (F2 opens it again).
- Full screen
On the first screen, F11. The mixer captures this screen (HDMI output, capture card, screen capture) and removes the green (chroma key).
- The view
Panel: “Starford overlay” for the Race and Results moments; for Presentation and Pause, an empty green view (or the overlay as well). Advertising after 0: no full-screen advertising in the video.
3. The display delay
The camera, the mixer and the encoder delay the picture: without correction, a skater's time is displayed before she is seen crossing the line. The delay is set in TABLEAU, by eye, live:
- Watch the mixer output
On the mixer's monitor (not on the TABLEAU screen), watch a crossing of the line and the moment “Lap N” changes.
- Adjust
DURATIONS → Display delay (ms, 0 to 10,000): 400, then 600, 800… until the time lands with the crossing. Applied on the fly: nothing is lost or shown twice; when increased, the clock jumps back by the difference.
Under the panel's clock: “Display delay: 800 ms”. Nothing is added to the broadcast picture.