The audio objects can be set to one of the following states from the GTT:
- Normal (default state on boot-up)
- Bypass
- Mute
- Stop
These options are available to all regular audio objects with equal number of input and output channels. For source objects like Waveform generator, only Normal and Mute states are allowed. This feature is not available to the interface objects like Audio-in/out, Control-in/out. For the compound audio objects, the selected state will be applied to all inner audio objects.
Following are the tasks carried out every time an audio interrupt is received for each state:
- Normal: Normal operation with update of necessary internal states of the audio object; normal output.
- Bypass: Normal operation with update of necessary internal states of the audio object; input channel buffer data copied to the output channel buffers.
- Mute: Normal operation with update of necessary internal states of the audio object; output channel buffers cleared to zero.
- Stop: Input channel buffer data copied to the output channel buffers (no update of internal states).
Ramping
To ensure smooth transition across states, linear ramping is provided with the ramp-up OR ramp-down time of 50 ms. Ramping is not provided for any transitions involving Bypass state and the individual audio object need to support this.
For transition between Normal and Stop states, first the output is ramped down from the present state to mute state and then ramped up to the target state.