HD-SDI

Embedded audio

Both the HD and SD serial interfaces provide for 16 channels of embedded audio. The two interfaces use different audio encapsulation methods--SD uses the SMPTE 272M standard, whereas HD uses the SMPTE 299M standard. In either case, a SDI signal may contain up to sixteen audio channels (8 pairs) embedded 48 kHz, 24-bit audio channels along with the video. Typically, 48 kHz, 24-bit (20-bit in SD) PCM audio is stored, in a manner directly compatible with the AES3 digital audio interface. These are placed in the (horizontal) blanking periods, when the SDI signal carries nothing useful, since the receiver generates its own blanking signals from the TRS.

In dual-link applications, 32 channels of audio are available, as each link may carry 16 channels.

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