| page.title=3A Modes and State Transition |
| @jd:body |
| |
| <!-- |
| Copyright 2013 The Android Open Source Project |
| |
| Licensed under the Apache License, Version 2.0 (the "License"); |
| you may not use this file except in compliance with the License. |
| You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| --> |
| <div id="qv-wrapper"> |
| <div id="qv"> |
| <h2>In this document</h2> |
| <ol id="auto-toc"> |
| </ol> |
| </div> |
| </div> |
| |
| <p> |
| While the actual 3A algorithms are up to the HAL implementation, a high-level |
| state machine description is defined by the HAL interface to allow the HAL |
| device and the framework to communicate about the current state of 3A and |
| trigger 3A events.</p> |
| <p>When the device is opened, all the individual 3A states must be STATE_INACTIVE. |
| Stream configuration does not reset 3A. For example, locked focus must be |
| maintained across the configure() call.</p> |
| <p>Triggering a 3A action involves simply setting the relevant trigger entry in the |
| settings for the next request to indicate start of trigger. For example, the |
| trigger for starting an autofocus scan is setting the entry |
| ANDROID_CONTROL_AF_TRIGGER to ANDROID_CONTROL_AF_TRIGGER_START for one request; |
| and cancelling an autofocus scan is triggered by setting |
| ANDROID_CONTROL_AF_TRIGGER to ANDROID_CONTRL_AF_TRIGGER_CANCEL. Otherwise, the |
| entry will not exist or be set to ANDROID_CONTROL_AF_TRIGGER_IDLE. Each request |
| with a trigger entry set to a non-IDLE value will be treated as an independent |
| triggering event.</p> |
| <p>At the top level, 3A is controlled by the ANDROID_CONTROL_MODE setting. It |
| selects between no 3A (ANDROID_CONTROL_MODE_OFF), normal AUTO mode |
| (ANDROID_CONTROL_MODE_AUTO), and using the scene mode setting |
| (ANDROID_CONTROL_USE_SCENE_MODE):</p> |
| <ul> |
| <li>In OFF mode, each of the individual Auto-focus(AF), auto-exposure (AE), and |
| auto-whitebalance (AWB) modes are effectively OFF, and none of the capture |
| controls may be overridden by the 3A routines.</li> |
| <li>In AUTO mode, AF, AE, and AWB modes all run their own independent algorithms, |
| and have their own mode, state, and trigger metadata entries, as listed in the |
| next section.</li> |
| <li>In USE_SCENE_MODE, the value of the ANDROID_CONTROL_SCENE_MODE entry must be |
| used to determine the behavior of 3A routines. In SCENE_MODEs other than |
| FACE_PRIORITY, the HAL must override the values of |
| ANDROID_CONTROL_AE/AWB/AF_MODE to be the mode it prefers for the selected |
| SCENE_MODE. For example, the HAL may prefer SCENE_MODE_NIGHT to use |
| CONTINUOUS_FOCUS AF mode. Any user selection of AE/AWB/AF_MODE when scene must |
| be ignored for these scene modes.</li> |
| <li>For SCENE_MODE_FACE_PRIORITY, the AE/AWB/AFMODE controls work as in |
| ANDROID_CONTROL_MODE_AUTO, but the 3A routines must bias toward metering and |
| focusing on any detected faces in the scene.</li> |
| </ul> |
| <h2 id="auto-focus">Auto-focus settings and result entries</h2> |
| <p>Main metadata entries:<br/> |
| ANDROID_CONTROL_AF_MODE: Control for selecting the current autofocus mode. Set |
| by the framework in the request settings.<br/> |
| AF_MODE_OFF: AF is disabled; the framework/app directly controls lens position.<br/> |
| AF_MODE_AUTO: Single-sweep autofocus. No lens movement unless AF is triggered.<br/> |
| AF_MODE_MACRO: Single-sweep up-close autofocus. No lens movement unless AF is |
| triggered.<br/> |
| AF_MODE_CONTINUOUS_VIDEO: Smooth continuous focusing, for recording video. |
| Triggering immediately locks focus in current position. Canceling resumes |
| continuous focusing.<br/> |
| AF_MODE_CONTINUOUS_PICTURE: Fast continuous focusing, for zero-shutter-lag still |
| capture. Triggering locks focus once currently active sweep concludes. Canceling |
| resumes continuous focusing.<br/> |
| AF_MODE_EDOF: Advanced extended depth of field focusing. There is no autofocus |
| scan, so triggering one or canceling one has no effect. Images are focused |
| automatically by the HAL.<br/> |
| ANDROID_CONTROL_AF_STATE: Dynamic metadata describing the current AF algorithm |
| state, reported by the HAL in the result metadata.<br/> |
| AF_STATE_INACTIVE: No focusing has been done, or algorithm was reset. Lens is |
| not moving. Always the state for MODE_OFF or MODE_EDOF. When the device is |
| opened, it must start in this state.<br/> |
| AF_STATE_PASSIVE_SCAN: A continuous focus algorithm is currently scanning for |
| good focus. The lens is moving.<br/> |
| AF_STATE_PASSIVE_FOCUSED: A continuous focus algorithm believes it is well |
| focused. The lens is not moving. The HAL may spontaneously leave this state.<br/> |
| AF_STATE_PASSIVE_UNFOCUSED: A continuous focus algorithm believes it is not well |
| focused. The lens is not moving. The HAL may spontaneously leave this state.<br/> |
| AF_STATE_ACTIVE_SCAN: A scan triggered by the user is underway.<br/> |
| AF_STATE_FOCUSED_LOCKED: The AF algorithm believes it is focused. The lens is |
| not moving.<br/> |
| AF_STATE_NOT_FOCUSED_LOCKED: The AF algorithm has been unable to focus. The lens |
| is not moving.<br/> |
| ANDROID_CONTROL_AFTRIGGER: Control for starting an autofocus scan, the meaning |
| of which depends on mode and state. Set by the framework in the request |
| settings.<br/> |
| AF_TRIGGER_IDLE: No current trigger.<br/> |
| AF_TRIGGER_START: Trigger start of AF scan. Effect depends on mode and state.<br/> |
| AF_TRIGGER_CANCEL: Cancel current AF scan if any, and reset algorithm to |
| default.<br/> |
| Additional metadata entries:<br/> |
| ANDROID_CONTROL_AF_REGIONS: Control for selecting the regions of the field of |
| view (FOV) that should be used to determine good focus. This applies to all AF |
| modes that scan for focus. Set by the framework in the request settings.</p> |
| <h2 id="auto-exposure">Auto-exposure settings and result entries</h2> |
| <p>Main metadata entries:<br/> |
| ANDROID_CONTROL_AE_MODE: Control for selecting the current auto-exposure mode. |
| Set by the framework in the request settings.<br/> |
| AE_MODE_OFF: Autoexposure is disabled; the user controls exposure, gain, frame |
| duration, and flash.<br/> |
| AE_MODE_ON: Standard autoexposure, with flash control disabled. User may set |
| flash to fire or to torch mode.<br/> |
| AE_MODE_ON_AUTO_FLASH: Standard autoexposure, with flash on at HAL's discretion |
| for precapture and still capture. User control of flash disabled.<br/> |
| AE_MODE_ON_ALWAYS_FLASH: Standard autoexposure, with flash always fired for |
| capture, and at HAL's discretion for precapture. User control of flash disabled.<br/> |
| AE_MODE_ON_AUTO_FLASH_REDEYE: Standard autoexposure, with flash on at HAL's |
| discretion for precapture and still capture. Use a flash burst at end of |
| precapture sequence to reduce redeye in the final picture. User control of flash |
| disabled.<br/> |
| ANDROID_CONTROL_AE_STATE: Dynamic metadata describing the current AE algorithm |
| state, reported by the HAL in the result metadata.<br/> |
| AE_STATE_INACTIVE: Initial AE state after mode switch. When the device is |
| opened, it must start in this state.<br/> |
| AE_STATE_SEARCHING: AE is not converged to a good value and is adjusting |
| exposure parameters.<br/> |
| AE_STATE_CONVERGED: AE has found good exposure values for the current scene, and |
| the exposure parameters are not changing. HAL may spontaneously leave this state |
| to search for a better solution.<br/> |
| AE_STATE_LOCKED: AE has been locked with the AE_LOCK control. Exposure values |
| are not changing.<br/> |
| AE_STATE_FLASH_REQUIRED: The HAL has converged exposure but believes flash is |
| required for a sufficiently bright picture. Used for determining if a |
| zero-shutter-lag frame can be used.<br/> |
| AE_STATE_PRECAPTURE: The HAL is in the middle of a precapture sequence. |
| Depending on AE mode, this mode may involve firing the flash for metering or a |
| burst of flash pulses for redeye reduction.<br/> |
| ANDROID_CONTROL_AE_PRECAPTURE_TRIGGER: Control for starting a metering sequence |
| before capturing a high-quality image. Set by the framework in the request |
| settings.<br/> |
| PRECAPTURE_TRIGGER_IDLE: No current trigger.<br/> |
| PRECAPTURE_TRIGGER_START: Start a precapture sequence. The HAL should use the |
| subsequent requests to measure good exposure/white balance for an upcoming |
| high-resolution capture.<br/> |
| Additional metadata entries:<br/> |
| ANDROID_CONTROL_AE_LOCK: Control for locking AE controls to their current |
| values.<br/> |
| ANDROID_CONTROL_AE_EXPOSURE_COMPENSATION: Control for adjusting AE algorithm |
| target brightness point.<br/> |
| ANDROID_CONTROL_AE_TARGET_FPS_RANGE: Control for selecting the target frame rate |
| range for the AE algorithm. The AE routine cannot change the frame rate to be |
| outside these bounds.<br/> |
| ANDROID_CONTROL_AE_REGIONS: Control for selecting the regions of the FOV that |
| should be used to determine good exposure levels. This applies to all AE modes |
| besides OFF.</p> |
| <h2 id="auto-wb">Auto-whitebalance settings and result entries</h2> |
| <p>Main metadata entries:<br/> |
| ANDROID_CONTROL_AWB_MODE: Control for selecting the current white-balance mode.<br/> |
| AWB_MODE_OFF: Auto-whitebalance is disabled. User controls color matrix.<br/> |
| AWB_MODE_AUTO: Automatic white balance is enabled; 3A controls color transform, |
| possibly using more complex transforms than a simple matrix.<br/> |
| AWB_MODE_INCANDESCENT: Fixed white balance settings good for indoor incandescent |
| (tungsten) lighting, roughly 2700K.<br/> |
| AWB_MODE_FLUORESCENT: Fixed white balance settings good for fluorescent |
| lighting, roughly 5000K.<br/> |
| AWB_MODE_WARM_FLUORESCENT: Fixed white balance settings good for fluorescent |
| lighting, roughly 3000K.<br/> |
| AWB_MODE_DAYLIGHT: Fixed white balance settings good for daylight, roughly |
| 5500K.<br/> |
| AWB_MODE_CLOUDY_DAYLIGHT: Fixed white balance settings good for clouded |
| daylight, roughly 6500K.<br/> |
| AWB_MODE_TWILIGHT: Fixed white balance settings good for near-sunset/sunrise, |
| roughly 15000K.<br/> |
| AWB_MODE_SHADE: Fixed white balance settings good for areas indirectly lit by |
| the sun, roughly 7500K.<br/> |
| ANDROID_CONTROL_AWB_STATE: Dynamic metadata describing the current AWB algorithm |
| state, reported by the HAL in the result metadata.<br/> |
| AWB_STATE_INACTIVE: Initial AWB state after mode switch. When the device is |
| opened, it must start in this state.<br/> |
| AWB_STATE_SEARCHING: AWB is not converged to a good value and is changing color |
| adjustment parameters.<br/> |
| AWB_STATE_CONVERGED: AWB has found good color adjustment values for the current |
| scene, and the parameters are not changing. HAL may spontaneously leave this |
| state to search for a better solution.<br/> |
| AWB_STATE_LOCKED: AWB has been locked with the AWB_LOCK control. Color |
| adjustment values are not changing.<br/> |
| Additional metadata entries:<br/> |
| ANDROID_CONTROL_AWB_LOCK: Control for locking AWB color adjustments to their |
| current values.<br/> |
| ANDROID_CONTROL_AWB_REGIONS: Control for selecting the regions of the FOV that |
| should be used to determine good color balance. This applies only to |
| auto-whitebalance mode.</p> |
| <h2 id="state-transition">General state machine transition notes</h2> |
| <p>Switching between AF, AE, or AWB modes always resets the algorithm's state to |
| INACTIVE. Similarly, switching between CONTROL_MODE or CONTROL_SCENE_MODE if |
| CONTROL_MODE == USE_SCENE_MODE resets all the algorithm states to INACTIVE.<br/> |
| The tables below are per-mode.</p> |
| <h2 id="af-state">AF state machines</h2> |
| <table> |
| <tr> |
| <td><strong>mode = AF_MODE_OFF or AF_MODE_EDOF</strong></td> |
| <td></td> |
| <td></td> |
| <td></td> |
| </tr> |
| <tr> |
| <th>State</th> |
| <th>Transformation cause</th> |
| <th>New state</th> |
| <th>Notes</th> |
| </tr> |
| <tr> |
| <td>INACTIVE</td> |
| <td></td> |
| <td></td> |
| <td>AF is disabled</td> |
| </tr> |
| <tr> |
| <td><strong>mode = AF_MODE_AUTO or AF_MODE_MACRO</strong></td> |
| <td></td> |
| <td></td> |
| <td></td> |
| </tr> |
| <tr> |
| <th>State</th> |
| <th>Transformation cause</th> |
| <th>New state</th> |
| <th>Notes</th> |
| </tr> |
| <tr> |
| <td>INACTIVE</td> |
| <td>AF_TRIGGER</td> |
| <td>ACTIVE_SCAN</td> |
| <td>Start AF sweep |
| Lens now moving</td> |
| </tr> |
| <tr> |
| <td>ACTIVE_SCAN</td> |
| <td>AF sweep done</td> |
| <td>FOCUSED_LOCKED</td> |
| <td>If AF successful |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>ACTIVE_SCAN</td> |
| <td>AF sweep done</td> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>If AF successful |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>ACTIVE_SCAN</td> |
| <td>AF_CANCEL</td> |
| <td>INACTIVE</td> |
| <td>Cancel/reset AF |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>FOCUSED_LOCKED</td> |
| <td>AF_CANCEL</td> |
| <td>INACTIVE</td> |
| <td>Cancel/reset AF</td> |
| </tr> |
| <tr> |
| <td>FOCUSED_LOCKED</td> |
| <td>AF_TRIGGER</td> |
| <td>ACTIVE_SCAN</td> |
| <td>Start new sweep |
| Lens now moving</td> |
| </tr> |
| <tr> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>AF_CANCEL</td> |
| <td>INACTIVE</td> |
| <td>Cancel/reset AF</td> |
| </tr> |
| <tr> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>AF_TRIGGER</td> |
| <td>ACTIVE_SCAN</td> |
| <td>Start new sweep |
| Lens now moving</td> |
| </tr> |
| <tr> |
| <td>All states</td> |
| <td>mode change</td> |
| <td>INACTIVE</td> |
| <td></td> |
| </tr> |
| <tr> |
| <td><strong>mode = AF_MODE_CONTINUOUS_VIDEO</strong></td> |
| <td></td> |
| <td></td> |
| <td></td> |
| </tr> |
| <tr> |
| <th>State</th> |
| <th>Transformation cause</th> |
| <th>New state</th> |
| <th>Notes</th> |
| </tr> |
| <tr> |
| <td>INACTIVE</td> |
| <td>HAL initiates new scan</td> |
| <td>PASSIVE_SCAN</td> |
| <td>Start AF sweep |
| Lens now moving</td> |
| </tr> |
| <tr> |
| <td>INACTIVE</td> |
| <td>AF_TRIGGER</td> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>AF state query |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_SCAN</td> |
| <td>HAL completes current scan</td> |
| <td>PASSIVE_FOCUSED</td> |
| <td>End AF scan |
| Lens now locked </td> |
| </tr> |
| <tr> |
| <td>PASSIVE_SCAN</td> |
| <td>AF_TRIGGER</td> |
| <td>FOCUSED_LOCKED</td> |
| <td>Immediate transformation |
| if focus is good |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_SCAN</td> |
| <td>AF_TRIGGER</td> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>Immediate transformation |
| if focus is bad |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_SCAN</td> |
| <td>AF_CANCEL</td> |
| <td>INACTIVE</td> |
| <td>Reset lens position |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_FOCUSED</td> |
| <td>HAL initiates new scan</td> |
| <td>PASSIVE_SCAN</td> |
| <td>Start AF scan |
| Lens now moving</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_FOCUSED</td> |
| <td>AF_TRIGGER</td> |
| <td>FOCUSED_LOCKED</td> |
| <td>Immediate transformation |
| if focus is good |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_FOCUSED</td> |
| <td>AF_TRIGGER</td> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>Immediate transformation |
| if focus is bad |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>FOCUSED_LOCKED</td> |
| <td>AF_TRIGGER</td> |
| <td>FOCUSED_LOCKED</td> |
| <td>No effect</td> |
| </tr> |
| <tr> |
| <td>FOCUSED_LOCKED</td> |
| <td>AF_CANCEL</td> |
| <td>INACTIVE</td> |
| <td>Restart AF scan</td> |
| </tr> |
| <tr> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>AF_TRIGGER</td> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>No effect</td> |
| </tr> |
| <tr> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>AF_CANCEL</td> |
| <td>INACTIVE</td> |
| <td>Restart AF scan</td> |
| </tr> |
| <tr> |
| <td><strong>mode = AF_MODE_CONTINUOUS_PICTURE</strong></td> |
| <td></td> |
| <td></td> |
| <td></td> |
| </tr> |
| <tr> |
| <th>State</th> |
| <th>Transformation cause</th> |
| <th>New state</th> |
| <th>Notes</th> |
| </tr> |
| <tr> |
| <td>INACTIVE</td> |
| <td>HAL initiates new scan</td> |
| <td>PASSIVE_SCAN</td> |
| <td>Start AF scan |
| Lens now moving</td> |
| </tr> |
| <tr> |
| <td>INACTIVE</td> |
| <td>AF_TRIGGER</td> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>AF state query |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_SCAN</td> |
| <td>HAL completes current scan</td> |
| <td>PASSIVE_FOCUSED</td> |
| <td>End AF scan |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_SCAN</td> |
| <td>AF_TRIGGER</td> |
| <td>FOCUSED_LOCKED</td> |
| <td>Eventual transformation once focus good |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_SCAN</td> |
| <td>AF_TRIGGER</td> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>Eventual transformation if cannot focus |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_SCAN</td> |
| <td>AF_CANCEL</td> |
| <td>INACTIVE</td> |
| <td>Reset lens position |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_FOCUSED</td> |
| <td>HAL initiates new scan</td> |
| <td>PASSIVE_SCAN</td> |
| <td>Start AF scan |
| Lens now moving</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_FOCUSED</td> |
| <td>AF_TRIGGER</td> |
| <td>FOCUSED_LOCKED</td> |
| <td>Immediate transformation if focus is good |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>PASSIVE_FOCUSED</td> |
| <td>AF_TRIGGER</td> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>Immediate transformation if focus is bad |
| Lens now locked</td> |
| </tr> |
| <tr> |
| <td>FOCUSED_LOCKED</td> |
| <td>AF_TRIGGER</td> |
| <td>FOCUSED_LOCKED</td> |
| <td>No effect</td> |
| </tr> |
| <tr> |
| <td>FOCUSED_LOCKED</td> |
| <td>AF_CANCEL</td> |
| <td>INACTIVE</td> |
| <td>Restart AF scan</td> |
| </tr> |
| <tr> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>AF_TRIGGER</td> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>No effect</td> |
| </tr> |
| <tr> |
| <td>NOT_FOCUSED_LOCKED</td> |
| <td>AF_CANCEL</td> |
| <td>INACTIVE</td> |
| <td>Restart AF scan</td> |
| </tr> |
| </table> |
| <h2 id="ae-wb">AE and AWB state machines</h2> |
| <p>The AE and AWB state machines are mostly identical. AE has additional |
| FLASH_REQUIRED and PRECAPTURE states. So rows below that refer to those two |
| states should be ignored for the AWB state machine.</p> |
| <table> |
| <tr> |
| <td><strong>mode = AE_MODE_OFF / AWB mode not AUTO</strong></td> |
| <td></td> |
| <td></td> |
| <td></td> |
| </tr> |
| <tr> |
| <th>State</th> |
| <th>Transformation cause</th> |
| <th>New state</th> |
| <th>Notes</th> |
| </tr> |
| <tr> |
| <td>INACTIVE</td> |
| <td></td> |
| <td></td> |
| <td>AE/AWB disabled</td> |
| </tr> |
| <tr> |
| <td><strong>mode = AE_MODE_ON_* / AWB_MODE_AUTO</strong></td> |
| <td></td> |
| <td></td> |
| <td></td> |
| </tr> |
| <tr> |
| <th>State</th> |
| <th>Transformation cause</th> |
| <th>New state</th> |
| <th>Notes</th> |
| </tr> |
| <tr> |
| <td>INACTIVE</td> |
| <td>HAL initiates AE/AWB scan</td> |
| <td>SEARCHING</td> |
| <td></td> |
| </tr> |
| <tr> |
| <td>INACTIVE</td> |
| <td>AE/AWB_LOCK on</td> |
| <td>LOCKED</td> |
| <td>Values locked</td> |
| </tr> |
| <tr> |
| <td>SEARCHING</td> |
| <td>HAL finishes AE/AWB scan</td> |
| <td>CONVERGED</td> |
| <td>Good values, not changing</td> |
| </tr> |
| <tr> |
| <td>SEARCHING</td> |
| <td>HAL finishes AE scan</td> |
| <td>FLASH_REQUIRED</td> |
| <td>Converged but too dark without flash</td> |
| </tr> |
| <tr> |
| <td>SEARCHING</td> |
| <td>AE/AWB_LOCK on</td> |
| <td>LOCKED</td> |
| <td>Values locked</td> |
| </tr> |
| <tr> |
| <td>CONVERGED</td> |
| <td>HAL initiates AE/AWB scan</td> |
| <td>SEARCHING</td> |
| <td>Values locked</td> |
| </tr> |
| <tr> |
| <td>CONVERGED</td> |
| <td>AE/AWB_LOCK on</td> |
| <td>LOCKED</td> |
| <td>Values locked</td> |
| </tr> |
| <tr> |
| <td>FLASH_REQUIRED</td> |
| <td>HAL initiates AE/AWB scan</td> |
| <td>SEARCHING</td> |
| <td>Values locked</td> |
| </tr> |
| <tr> |
| <td>FLASH_REQUIRED</td> |
| <td>AE/AWB_LOCK on</td> |
| <td>LOCKED</td> |
| <td>Values locked</td> |
| </tr> |
| <tr> |
| <td>LOCKED</td> |
| <td>AE/AWB_LOCK off</td> |
| <td>SEARCHING</td> |
| <td>Values not good after unlock</td> |
| </tr> |
| <tr> |
| <td>LOCKED</td> |
| <td>AE/AWB_LOCK off</td> |
| <td>CONVERGED</td> |
| <td>Values good after unlock</td> |
| </tr> |
| <tr> |
| <td>LOCKED</td> |
| <td>AE_LOCK off</td> |
| <td>FLASH_REQUIRED</td> |
| <td>Exposure good, but too dark</td> |
| </tr> |
| <tr> |
| <td>All AE states</td> |
| <td>PRECAPTURE_START</td> |
| <td>PRECAPTURE</td> |
| <td>Start precapture sequence</td> |
| </tr> |
| <tr> |
| <td>PRECAPTURE</td> |
| <td>Sequence done, AE_LOCK off</td> |
| <td>CONVERGED</td> |
| <td>Ready for high-quality capture</td> |
| </tr> |
| <tr> |
| <td>PRECAPTURE</td> |
| <td>Sequence done, AE_LOCK on</td> |
| <td>LOCKED</td> |
| <td>Ready for high-quality capture</td> |
| </tr> |
| </table> |
| <h2 id="manual-control">Enabling manual control</h2> |
| <p>Several controls are also involved in configuring the device 3A blocks to allow |
| for direct application control.</p> |
| <p>The HAL model for 3A control is that for each request, the HAL inspects the |
| state of the 3A control fields. If any 3A routine is enabled, then that routine |
| overrides the control variables that relate to that routine, and these override |
| values are then available in the result metadata for that capture. So for |
| example, if auto-exposure is enabled in a request, the HAL should overwrite the |
| exposure, gain, and frame duration fields (and potentially the flash fields, |
| depending on AE mode) of the request. The list of relevant controls is:</p> |
| <table> |
| <tr> |
| <th>Control name</th> |
| <th>Unit</th> |
| <th>Notes</th> |
| </tr> |
| <tr> |
| <td>android.control.mode</td> |
| <td>enum: OFF, AUTO, USE_SCENE_MODE</td> |
| <td>High-level 3A control. When set to OFF, all 3A control by the HAL is disabled. The application must set the fields for capture parameters itself. |
| When set to AUTO, the individual algorithm controls in android.control.* are in effect, such as android.control.afMode. |
| When set to USE_SCENE_MODE, the individual controls in android.control.* are mostly disabled, and the HAL implements one of the scene mode settings (such as ACTION, SUNSET, or PARTY) as it wishes.</td> |
| </tr> |
| <tr> |
| <td>android.control.afMode</td> |
| <td>enum</td> |
| <td>OFF means manual control of lens focusing through android.lens.focusDistance.</td> |
| </tr> |
| <tr> |
| <td>android.control.aeMode</td> |
| <td>enum</td> |
| <td>OFF means manual control of exposure/gain/frame duration through android.sensor.exposureTime / .sensitivity / .frameDuration</td> |
| </tr> |
| <tr> |
| <td>android.control.awbMode</td> |
| <td>enum</td> |
| <td>OFF means manual control of white balance. </td> |
| </tr> |
| </table> |
