Master Clock
The master clock allows devices that require accurate timing to be synchronised. The clock signal is distributed through the Facility Panels.
Clock synchronisation is critically important when pairing audio and video, or when using multiple audio or video devices together. If devices do not receive accurate clock signals they will drift, causing artefacts and communication problems.
Rates
The clock rates have been chosen to provide the greatest degree of interoperability between devices according to standards set by the AES.
- Audio clock rate: 48kHz
- Video clock rate: 1080i50 (HD)
The house clock rates cannot be changed. If you require different clock rates, you must use standalone clocking generated by a local device as the master.
It is recommended that 48kHz be used in preference to 44.1kHz for audio recording [1], which provides the highest quality for the latest audio format standards (eg. Blu-ray and Dolby Atmos) and the greatest degree of compatibility. However, the recording studios each default to local 44.1kHz clocking for historical reasons.
Clocking
Devices can be clocked locally or synchronised to a high definition master clock which ensures every device receives the same timing pulse. This can be used to ensure a transmission 'lock' can be maintained between digital devices and is especially critical when working with audio for video content.
Hardware
New Adelphi uses an Antelope Isochrone Trinity master clock. This unit provides three audio clock outputs, three HD video clock outputs and four SD clock outputs.
- ↑ Audio Engineering Society, Inc., AES recommended practice for professional digital audio - Preferred sampling frequencies for applications employing pulse-code modulation (Audio Engineering Society, 2008) - AES5-2008