Closed Captions

Quadra supports EIA CEA-708 closed captions for H.264, H.265, and AV1. There are no special encoder parameters to set, the Quadra decoder automatically passes closed captions up to FFmpeg if present in the bitstream and the Quadra encoder will automatically insert closed captions in the encoded bitstream if they are present in the incoming stream to encoder. FFmpeg stores CE708 closed captions as ATSC A53 Part 4 Closed Captions side data. Closed captions are stored in the encoded bitstreams as T.35 payloads formatted according to CEA-708.