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MultiCam Boards Documentation > MultiCam Documentation > MultiCam User Guide > MultiCam Basics > Acquisition > Acquisition Sequence
Acquisition Sequence

An acquisition sequence is a succession of acquisition phases.

The successive acquisition phases are not necessarily contiguous in time. Intervening gaps of various duration can be present between acquisition phases.

An acquisition sequence starts at SAS event (Start of Acquisition Sequence). It occurs either at TE (Trigger Event), or automatically according to the chosen acquisition mode.

When completing the acquisition sequence, the channel issues an event called EAS (End of Acquisition Sequence).

Acquisition sequence

For more information, refer to the MultiCam Acquisition Principles application note.

Speeding-Up the Start of Acquisition Sequence

Normally, starting an acquisition sequence involves no delay. The time interval between the software activation and the effective SAS event is less than one millisecond.

However, under certain circumstances, the activation time can be longer (several tens of milliseconds).

The circumstances for a slowed down channel activation are as follows:

A format-related parameter is a channel-, processor- or surface-class parameter the update of which induces a change in the format characteristics of the destination surface. Specifically, any change of size, bit-width or plane structure in the acquisition or processing destination surface will be taken into account at the next channel activation, and this will take a noticeable amount of time.

MultiCam provides a way to speed up the channel activation to alleviate this restriction.

When a channel is in the IDLE state, as reflected by the channel parameter ChannelState, the application software is allowed to set this parameter to the pseudo-state READY.

In doing this, the MultiCam system will try to make ready everything inside the channel in such a way that the next time the ChannelState parameter is set to ACTIVE, the channel activation is immediate (less than one millisecond).

Setting ChannelState to READY takes a short time to complete. The channel's state changes to READY if all required grabber resources are available. Otherwise, ChannelState remains ORPHAN.

For more information, see also Understanding Automatic Switching.