Sound friendly with Sandy
Using the video signal as an audio transport in multichannel recording practice has several advantages: Absolute synchronization of video and sound and reduced number of wires and connectors needed for video server connection in studio or OB Van. In most cases, this method is completely satisfactory.
Nevertheless, in some cases a different Workflow for working with audio is required. For example, during recording of concerts, when the multi-channel video server must record more audio channels than is possible using embedded audio or in situations when you want to record audio that is not tied to any of the video channels. Also, when required sound quality exceeds the standard quality of embedded audio. For example 96 kHz or 192 kHz sampling rate.
To solve such problems in Simple R Series servers, and for a greater integration with audio equipment, slomo.tv has developed the option «Sandy». It allows recording of up to 16 channels of audio in the professional standard AES / EBU and up to 128 channels of audio through MADI interface (optical and coaxial). The huge advantage of MADI is the ability to transmit over a single optical or coaxial cable up to 64 audio channels. Many modern audio mixers have MADI output which can dramatically reduce the number of connecting wires between the audio mixer and the recording system.
The total number of audio channels recorded by a video server equipped with Sandy can reach 240 channels for Simple R 662 and Simple R 662 Plus. Such a number of recording channels is a rarity even among professional multi-channel audio recording systems.
In case of using Sandy with existing sound equipment, it is mandatory to use common source for synchronizing audio and video. Otherwise the sample frequency used in digital audio will be different than desired multiple of 48KHz. This will lead to discarding of extra samples or sample duplication when their quantity is not enough. The problem can be solved by re-sampling of incoming audio, but in both cases the sound quality will suffer. That is why synchronization is so important!
The optimal solution for synchronizing video and audio is the use a Master clock generator, for example Evertz MC5601.
Another way is to use a special WordClock generator synchronized to video Genlock or to the video signal.