SDI — Serial Digital Interface
Definition
SDI (Serial Digital Interface) is a family of broadcast standards for transmitting uncompressed digital video over 75Ω coaxial cable with BNC connectors. The main data rates are 1.485 Gbps for HD-SDI (SMPTE ST 292-1), 2.97 Gbps for 3G-SDI (SMPTE ST 424) at 1080p60, 5.94 Gbps for 6G-SDI (SMPTE ST 2081) at 4K30 and 11.88 Gbps for 12G-SDI (SMPTE ST 2082) at 4K60. SDI carries embedded audio: 16 channels in HD and 32 in 3G-SDI (SMPTE ST 299-1 and ST 299-2). Reach depends mainly on the data rate: around 300 m in standard definition, about 100 m in HD and a few tens of metres in 12G, depending on the cable. The connectors lock mechanically, and SDI is preferred over HDMI on critical broadcast paths.
In the field
SDI runs are usually tested with a signal analyser before an event, because cable faults that cause intermittent errors at full data rate pass a visual inspection. A single damaged metre of cable can be enough to interrupt the signal during the show.
Related lessons
Sources
- SMPTE ST 292-1 : HD-SDI 1,485 et 1,485/1,001 Gb/s sur coaxial 75 Ω · en.wikipedia.org
- SMPTE ST 424 (3G, 2,97 Gb/s), ST 2081 (6G, 5,94 Gb/s, 2160p30), ST 2082 (12G, 11,88 Gb/s, 2160p60) · pub.smpte.org
- SMPTE ST 299-1 / ST 299-2, audio embarqué : 16 canaux en HD, 32 canaux en 3G-SDI · standards.globalspec.com
- SMPTE ST 292 : portée définie par 20 dB de perte à la moitié de la fréquence d'horloge (environ 100 m en HD) · extron.com
- Belden, 1694A : environ 78 m conformes en 3G/6G ; le 12G nécessite un coaxial dédié · belden.com