1 <html devsite> 2 <head> 3 <title>3A Modes and State Transition</title> 4 <meta name="project_path" value="/_project.yaml" /> 5 <meta name="book_path" value="/_book.yaml" /> 6 </head> 7 <body> 8 <!-- 9 Copyright 2017 The Android Open Source Project 10 11 Licensed under the Apache License, Version 2.0 (the "License"); 12 you may not use this file except in compliance with the License. 13 You may obtain a copy of the License at 14 15 http://www.apache.org/licenses/LICENSE-2.0 16 17 Unless required by applicable law or agreed to in writing, software 18 distributed under the License is distributed on an "AS IS" BASIS, 19 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 20 See the License for the specific language governing permissions and 21 limitations under the License. 22 --> 23 24 25 26 <p> 27 While the actual 3A algorithms are up to the HAL implementation, a high-level 28 state machine description is defined by the HAL interface to allow the HAL 29 device and the framework to communicate about the current state of 3A and 30 trigger 3A events.</p> 31 <p>When the device is opened, all the individual 3A states must be STATE_INACTIVE. 32 Stream configuration does not reset 3A. For example, locked focus must be 33 maintained across the configure() call.</p> 34 <p>Triggering a 3A action involves simply setting the relevant trigger entry in the 35 settings for the next request to indicate start of trigger. For example, the 36 trigger for starting an autofocus scan is setting the entry 37 ANDROID_CONTROL_AF_TRIGGER to ANDROID_CONTROL_AF_TRIGGER_START for one request; 38 and cancelling an autofocus scan is triggered by setting 39 ANDROID_CONTROL_AF_TRIGGER to ANDROID_CONTRL_AF_TRIGGER_CANCEL. Otherwise, the 40 entry will not exist or be set to ANDROID_CONTROL_AF_TRIGGER_IDLE. Each request 41 with a trigger entry set to a non-IDLE value will be treated as an independent 42 triggering event.</p> 43 <p>At the top level, 3A is controlled by the ANDROID_CONTROL_MODE setting. It 44 selects between no 3A (ANDROID_CONTROL_MODE_OFF), normal AUTO mode 45 (ANDROID_CONTROL_MODE_AUTO), and using the scene mode setting 46 (ANDROID_CONTROL_USE_SCENE_MODE):</p> 47 <ul> 48 <li>In OFF mode, each of the individual Auto-focus(AF), auto-exposure (AE), and 49 auto-whitebalance (AWB) modes are effectively OFF, and none of the capture 50 controls may be overridden by the 3A routines.</li> 51 <li>In AUTO mode, AF, AE, and AWB modes all run their own independent algorithms, 52 and have their own mode, state, and trigger metadata entries, as listed in the 53 next section.</li> 54 <li>In USE_SCENE_MODE, the value of the ANDROID_CONTROL_SCENE_MODE entry must be 55 used to determine the behavior of 3A routines. In SCENE_MODEs other than 56 FACE_PRIORITY, the HAL must override the values of 57 ANDROID_CONTROL_AE/AWB/AF_MODE to be the mode it prefers for the selected 58 SCENE_MODE. For example, the HAL may prefer SCENE_MODE_NIGHT to use 59 CONTINUOUS_FOCUS AF mode. Any user selection of AE/AWB/AF_MODE when scene must 60 be ignored for these scene modes.</li> 61 <li>For SCENE_MODE_FACE_PRIORITY, the AE/AWB/AFMODE controls work as in 62 ANDROID_CONTROL_MODE_AUTO, but the 3A routines must bias toward metering and 63 focusing on any detected faces in the scene.</li> 64 </ul> 65 <h2 id="auto-focus">Auto-focus settings and result entries</h2> 66 <p>Main metadata entries:<br/> 67 ANDROID_CONTROL_AF_MODE: Control for selecting the current autofocus mode. Set 68 by the framework in the request settings.<br/> 69 AF_MODE_OFF: AF is disabled; the framework/app directly controls lens position.<br/> 70 AF_MODE_AUTO: Single-sweep autofocus. No lens movement unless AF is triggered.<br/> 71 AF_MODE_MACRO: Single-sweep up-close autofocus. No lens movement unless AF is 72 triggered.<br/> 73 AF_MODE_CONTINUOUS_VIDEO: Smooth continuous focusing, for recording video. 74 Triggering immediately locks focus in current position. Canceling resumes 75 continuous focusing.<br/> 76 AF_MODE_CONTINUOUS_PICTURE: Fast continuous focusing, for zero-shutter-lag still 77 capture. Triggering locks focus once currently active sweep concludes. Canceling 78 resumes continuous focusing.<br/> 79 AF_MODE_EDOF: Advanced extended depth of field focusing. There is no autofocus 80 scan, so triggering one or canceling one has no effect. Images are focused 81 automatically by the HAL.<br/> 82 ANDROID_CONTROL_AF_STATE: Dynamic metadata describing the current AF algorithm 83 state, reported by the HAL in the result metadata.<br/> 84 AF_STATE_INACTIVE: No focusing has been done, or algorithm was reset. Lens is 85 not moving. Always the state for MODE_OFF or MODE_EDOF. When the device is 86 opened, it must start in this state.<br/> 87 AF_STATE_PASSIVE_SCAN: A continuous focus algorithm is currently scanning for 88 good focus. The lens is moving.<br/> 89 AF_STATE_PASSIVE_FOCUSED: A continuous focus algorithm believes it is well 90 focused. The lens is not moving. The HAL may spontaneously leave this state.<br/> 91 AF_STATE_PASSIVE_UNFOCUSED: A continuous focus algorithm believes it is not well 92 focused. The lens is not moving. The HAL may spontaneously leave this state.<br/> 93 AF_STATE_ACTIVE_SCAN: A scan triggered by the user is underway.<br/> 94 AF_STATE_FOCUSED_LOCKED: The AF algorithm believes it is focused. The lens is 95 not moving.<br/> 96 AF_STATE_NOT_FOCUSED_LOCKED: The AF algorithm has been unable to focus. The lens 97 is not moving.<br/> 98 ANDROID_CONTROL_AFTRIGGER: Control for starting an autofocus scan, the meaning 99 of which depends on mode and state. Set by the framework in the request 100 settings.<br/> 101 AF_TRIGGER_IDLE: No current trigger.<br/> 102 AF_TRIGGER_START: Trigger start of AF scan. Effect depends on mode and state.<br/> 103 AF_TRIGGER_CANCEL: Cancel current AF scan if any, and reset algorithm to 104 default.<br/> 105 Additional metadata entries:<br/> 106 ANDROID_CONTROL_AF_REGIONS: Control for selecting the regions of the field of 107 view (FOV) that should be used to determine good focus. This applies to all AF 108 modes that scan for focus. Set by the framework in the request settings.</p> 109 <h2 id="auto-exposure">Auto-exposure settings and result entries</h2> 110 <p>Main metadata entries:<br/> 111 ANDROID_CONTROL_AE_MODE: Control for selecting the current auto-exposure mode. 112 Set by the framework in the request settings.<br/> 113 AE_MODE_OFF: Autoexposure is disabled; the user controls exposure, gain, frame 114 duration, and flash.<br/> 115 AE_MODE_ON: Standard autoexposure, with flash control disabled. User may set 116 flash to fire or to torch mode.<br/> 117 AE_MODE_ON_AUTO_FLASH: Standard autoexposure, with flash on at HAL's discretion 118 for precapture and still capture. User control of flash disabled.<br/> 119 AE_MODE_ON_ALWAYS_FLASH: Standard autoexposure, with flash always fired for 120 capture, and at HAL's discretion for precapture. User control of flash disabled.<br/> 121 AE_MODE_ON_AUTO_FLASH_REDEYE: Standard autoexposure, with flash on at HAL's 122 discretion for precapture and still capture. Use a flash burst at end of 123 precapture sequence to reduce redeye in the final picture. User control of flash 124 disabled.<br/> 125 ANDROID_CONTROL_AE_STATE: Dynamic metadata describing the current AE algorithm 126 state, reported by the HAL in the result metadata.<br/> 127 AE_STATE_INACTIVE: Initial AE state after mode switch. When the device is 128 opened, it must start in this state.<br/> 129 AE_STATE_SEARCHING: AE is not converged to a good value and is adjusting 130 exposure parameters.<br/> 131 AE_STATE_CONVERGED: AE has found good exposure values for the current scene, and 132 the exposure parameters are not changing. HAL may spontaneously leave this state 133 to search for a better solution.<br/> 134 AE_STATE_LOCKED: AE has been locked with the AE_LOCK control. Exposure values 135 are not changing.<br/> 136 AE_STATE_FLASH_REQUIRED: The HAL has converged exposure but believes flash is 137 required for a sufficiently bright picture. Used for determining if a 138 zero-shutter-lag frame can be used.<br/> 139 AE_STATE_PRECAPTURE: The HAL is in the middle of a precapture sequence. 140 Depending on AE mode, this mode may involve firing the flash for metering or a 141 burst of flash pulses for redeye reduction.<br/> 142 ANDROID_CONTROL_AE_PRECAPTURE_TRIGGER: Control for starting a metering sequence 143 before capturing a high-quality image. Set by the framework in the request 144 settings.<br/> 145 PRECAPTURE_TRIGGER_IDLE: No current trigger.<br/> 146 PRECAPTURE_TRIGGER_START: Start a precapture sequence. The HAL should use the 147 subsequent requests to measure good exposure/white balance for an upcoming 148 high-resolution capture.<br/> 149 Additional metadata entries:<br/> 150 ANDROID_CONTROL_AE_LOCK: Control for locking AE controls to their current 151 values.<br/> 152 ANDROID_CONTROL_AE_EXPOSURE_COMPENSATION: Control for adjusting AE algorithm 153 target brightness point.<br/> 154 ANDROID_CONTROL_AE_TARGET_FPS_RANGE: Control for selecting the target frame rate 155 range for the AE algorithm. The AE routine cannot change the frame rate to be 156 outside these bounds.<br/> 157 ANDROID_CONTROL_AE_REGIONS: Control for selecting the regions of the FOV that 158 should be used to determine good exposure levels. This applies to all AE modes 159 besides OFF.</p> 160 <h2 id="auto-wb">Auto-whitebalance settings and result entries</h2> 161 <p>Main metadata entries:<br/> 162 ANDROID_CONTROL_AWB_MODE: Control for selecting the current white-balance mode.<br/> 163 AWB_MODE_OFF: Auto-whitebalance is disabled. User controls color matrix.<br/> 164 AWB_MODE_AUTO: Automatic white balance is enabled; 3A controls color transform, 165 possibly using more complex transforms than a simple matrix.<br/> 166 AWB_MODE_INCANDESCENT: Fixed white balance settings good for indoor incandescent 167 (tungsten) lighting, roughly 2700K.<br/> 168 AWB_MODE_FLUORESCENT: Fixed white balance settings good for fluorescent 169 lighting, roughly 5000K.<br/> 170 AWB_MODE_WARM_FLUORESCENT: Fixed white balance settings good for fluorescent 171 lighting, roughly 3000K.<br/> 172 AWB_MODE_DAYLIGHT: Fixed white balance settings good for daylight, roughly 173 5500K.<br/> 174 AWB_MODE_CLOUDY_DAYLIGHT: Fixed white balance settings good for clouded 175 daylight, roughly 6500K.<br/> 176 AWB_MODE_TWILIGHT: Fixed white balance settings good for near-sunset/sunrise, 177 roughly 15000K.<br/> 178 AWB_MODE_SHADE: Fixed white balance settings good for areas indirectly lit by 179 the sun, roughly 7500K.<br/> 180 ANDROID_CONTROL_AWB_STATE: Dynamic metadata describing the current AWB algorithm 181 state, reported by the HAL in the result metadata.<br/> 182 AWB_STATE_INACTIVE: Initial AWB state after mode switch. When the device is 183 opened, it must start in this state.<br/> 184 AWB_STATE_SEARCHING: AWB is not converged to a good value and is changing color 185 adjustment parameters.<br/> 186 AWB_STATE_CONVERGED: AWB has found good color adjustment values for the current 187 scene, and the parameters are not changing. HAL may spontaneously leave this 188 state to search for a better solution.<br/> 189 AWB_STATE_LOCKED: AWB has been locked with the AWB_LOCK control. Color 190 adjustment values are not changing.<br/> 191 Additional metadata entries:<br/> 192 ANDROID_CONTROL_AWB_LOCK: Control for locking AWB color adjustments to their 193 current values.<br/> 194 ANDROID_CONTROL_AWB_REGIONS: Control for selecting the regions of the FOV that 195 should be used to determine good color balance. This applies only to 196 auto-whitebalance mode.</p> 197 <h2 id="state-transition">General state machine transition notes</h2> 198 <p>Switching between AF, AE, or AWB modes always resets the algorithm's state to 199 INACTIVE. Similarly, switching between CONTROL_MODE or CONTROL_SCENE_MODE if 200 CONTROL_MODE == USE_SCENE_MODE resets all the algorithm states to INACTIVE.<br/> 201 The tables below are per-mode.</p> 202 <h2 id="af-state">AF state machines</h2> 203 <table> 204 <tr> 205 <td><strong>mode = AF_MODE_OFF or AF_MODE_EDOF</strong></td> 206 <td></td> 207 <td></td> 208 <td></td> 209 </tr> 210 <tr> 211 <th>State</th> 212 <th>Transformation cause</th> 213 <th>New state</th> 214 <th>Notes</th> 215 </tr> 216 <tr> 217 <td>INACTIVE</td> 218 <td></td> 219 <td></td> 220 <td>AF is disabled</td> 221 </tr> 222 <tr> 223 <td><strong>mode = AF_MODE_AUTO or AF_MODE_MACRO</strong></td> 224 <td></td> 225 <td></td> 226 <td></td> 227 </tr> 228 <tr> 229 <th>State</th> 230 <th>Transformation cause</th> 231 <th>New state</th> 232 <th>Notes</th> 233 </tr> 234 <tr> 235 <td>INACTIVE</td> 236 <td>AF_TRIGGER</td> 237 <td>ACTIVE_SCAN</td> 238 <td>Start AF sweep 239 Lens now moving</td> 240 </tr> 241 <tr> 242 <td>ACTIVE_SCAN</td> 243 <td>AF sweep done</td> 244 <td>FOCUSED_LOCKED</td> 245 <td>If AF successful 246 Lens now locked</td> 247 </tr> 248 <tr> 249 <td>ACTIVE_SCAN</td> 250 <td>AF sweep done</td> 251 <td>NOT_FOCUSED_LOCKED</td> 252 <td>If AF successful 253 Lens now locked</td> 254 </tr> 255 <tr> 256 <td>ACTIVE_SCAN</td> 257 <td>AF_CANCEL</td> 258 <td>INACTIVE</td> 259 <td>Cancel/reset AF 260 Lens now locked</td> 261 </tr> 262 <tr> 263 <td>FOCUSED_LOCKED</td> 264 <td>AF_CANCEL</td> 265 <td>INACTIVE</td> 266 <td>Cancel/reset AF</td> 267 </tr> 268 <tr> 269 <td>FOCUSED_LOCKED</td> 270 <td>AF_TRIGGER</td> 271 <td>ACTIVE_SCAN</td> 272 <td>Start new sweep 273 Lens now moving</td> 274 </tr> 275 <tr> 276 <td>NOT_FOCUSED_LOCKED</td> 277 <td>AF_CANCEL</td> 278 <td>INACTIVE</td> 279 <td>Cancel/reset AF</td> 280 </tr> 281 <tr> 282 <td>NOT_FOCUSED_LOCKED</td> 283 <td>AF_TRIGGER</td> 284 <td>ACTIVE_SCAN</td> 285 <td>Start new sweep 286 Lens now moving</td> 287 </tr> 288 <tr> 289 <td>All states</td> 290 <td>mode change</td> 291 <td>INACTIVE</td> 292 <td></td> 293 </tr> 294 <tr> 295 <td><strong>mode = AF_MODE_CONTINUOUS_VIDEO</strong></td> 296 <td></td> 297 <td></td> 298 <td></td> 299 </tr> 300 <tr> 301 <th>State</th> 302 <th>Transformation cause</th> 303 <th>New state</th> 304 <th>Notes</th> 305 </tr> 306 <tr> 307 <td>INACTIVE</td> 308 <td>HAL initiates new scan</td> 309 <td>PASSIVE_SCAN</td> 310 <td>Start AF sweep 311 Lens now moving</td> 312 </tr> 313 <tr> 314 <td>INACTIVE</td> 315 <td>AF_TRIGGER</td> 316 <td>NOT_FOCUSED_LOCKED</td> 317 <td>AF state query 318 Lens now locked</td> 319 </tr> 320 <tr> 321 <td>PASSIVE_SCAN</td> 322 <td>HAL completes current scan</td> 323 <td>PASSIVE_FOCUSED</td> 324 <td>End AF scan 325 Lens now locked </td> 326 </tr> 327 <tr> 328 <td>PASSIVE_SCAN</td> 329 <td>AF_TRIGGER</td> 330 <td>FOCUSED_LOCKED</td> 331 <td>Immediate transformation 332 if focus is good 333 Lens now locked</td> 334 </tr> 335 <tr> 336 <td>PASSIVE_SCAN</td> 337 <td>AF_TRIGGER</td> 338 <td>NOT_FOCUSED_LOCKED</td> 339 <td>Immediate transformation 340 if focus is bad 341 Lens now locked</td> 342 </tr> 343 <tr> 344 <td>PASSIVE_SCAN</td> 345 <td>AF_CANCEL</td> 346 <td>INACTIVE</td> 347 <td>Reset lens position 348 Lens now locked</td> 349 </tr> 350 <tr> 351 <td>PASSIVE_FOCUSED</td> 352 <td>HAL initiates new scan</td> 353 <td>PASSIVE_SCAN</td> 354 <td>Start AF scan 355 Lens now moving</td> 356 </tr> 357 <tr> 358 <td>PASSIVE_FOCUSED</td> 359 <td>AF_TRIGGER</td> 360 <td>FOCUSED_LOCKED</td> 361 <td>Immediate transformation 362 if focus is good 363 Lens now locked</td> 364 </tr> 365 <tr> 366 <td>PASSIVE_FOCUSED</td> 367 <td>AF_TRIGGER</td> 368 <td>NOT_FOCUSED_LOCKED</td> 369 <td>Immediate transformation 370 if focus is bad 371 Lens now locked</td> 372 </tr> 373 <tr> 374 <td>FOCUSED_LOCKED</td> 375 <td>AF_TRIGGER</td> 376 <td>FOCUSED_LOCKED</td> 377 <td>No effect</td> 378 </tr> 379 <tr> 380 <td>FOCUSED_LOCKED</td> 381 <td>AF_CANCEL</td> 382 <td>INACTIVE</td> 383 <td>Restart AF scan</td> 384 </tr> 385 <tr> 386 <td>NOT_FOCUSED_LOCKED</td> 387 <td>AF_TRIGGER</td> 388 <td>NOT_FOCUSED_LOCKED</td> 389 <td>No effect</td> 390 </tr> 391 <tr> 392 <td>NOT_FOCUSED_LOCKED</td> 393 <td>AF_CANCEL</td> 394 <td>INACTIVE</td> 395 <td>Restart AF scan</td> 396 </tr> 397 <tr> 398 <td><strong>mode = AF_MODE_CONTINUOUS_PICTURE</strong></td> 399 <td></td> 400 <td></td> 401 <td></td> 402 </tr> 403 <tr> 404 <th>State</th> 405 <th>Transformation cause</th> 406 <th>New state</th> 407 <th>Notes</th> 408 </tr> 409 <tr> 410 <td>INACTIVE</td> 411 <td>HAL initiates new scan</td> 412 <td>PASSIVE_SCAN</td> 413 <td>Start AF scan 414 Lens now moving</td> 415 </tr> 416 <tr> 417 <td>INACTIVE</td> 418 <td>AF_TRIGGER</td> 419 <td>NOT_FOCUSED_LOCKED</td> 420 <td>AF state query 421 Lens now locked</td> 422 </tr> 423 <tr> 424 <td>PASSIVE_SCAN</td> 425 <td>HAL completes current scan</td> 426 <td>PASSIVE_FOCUSED</td> 427 <td>End AF scan 428 Lens now locked</td> 429 </tr> 430 <tr> 431 <td>PASSIVE_SCAN</td> 432 <td>AF_TRIGGER</td> 433 <td>FOCUSED_LOCKED</td> 434 <td>Eventual transformation once focus good 435 Lens now locked</td> 436 </tr> 437 <tr> 438 <td>PASSIVE_SCAN</td> 439 <td>AF_TRIGGER</td> 440 <td>NOT_FOCUSED_LOCKED</td> 441 <td>Eventual transformation if cannot focus 442 Lens now locked</td> 443 </tr> 444 <tr> 445 <td>PASSIVE_SCAN</td> 446 <td>AF_CANCEL</td> 447 <td>INACTIVE</td> 448 <td>Reset lens position 449 Lens now locked</td> 450 </tr> 451 <tr> 452 <td>PASSIVE_FOCUSED</td> 453 <td>HAL initiates new scan</td> 454 <td>PASSIVE_SCAN</td> 455 <td>Start AF scan 456 Lens now moving</td> 457 </tr> 458 <tr> 459 <td>PASSIVE_FOCUSED</td> 460 <td>AF_TRIGGER</td> 461 <td>FOCUSED_LOCKED</td> 462 <td>Immediate transformation if focus is good 463 Lens now locked</td> 464 </tr> 465 <tr> 466 <td>PASSIVE_FOCUSED</td> 467 <td>AF_TRIGGER</td> 468 <td>NOT_FOCUSED_LOCKED</td> 469 <td>Immediate transformation if focus is bad 470 Lens now locked</td> 471 </tr> 472 <tr> 473 <td>FOCUSED_LOCKED</td> 474 <td>AF_TRIGGER</td> 475 <td>FOCUSED_LOCKED</td> 476 <td>No effect</td> 477 </tr> 478 <tr> 479 <td>FOCUSED_LOCKED</td> 480 <td>AF_CANCEL</td> 481 <td>INACTIVE</td> 482 <td>Restart AF scan</td> 483 </tr> 484 <tr> 485 <td>NOT_FOCUSED_LOCKED</td> 486 <td>AF_TRIGGER</td> 487 <td>NOT_FOCUSED_LOCKED</td> 488 <td>No effect</td> 489 </tr> 490 <tr> 491 <td>NOT_FOCUSED_LOCKED</td> 492 <td>AF_CANCEL</td> 493 <td>INACTIVE</td> 494 <td>Restart AF scan</td> 495 </tr> 496 </table> 497 <h2 id="ae-wb">AE and AWB state machines</h2> 498 <p>The AE and AWB state machines are mostly identical. AE has additional 499 FLASH_REQUIRED and PRECAPTURE states. So rows below that refer to those two 500 states should be ignored for the AWB state machine.</p> 501 <table> 502 <tr> 503 <td><strong>mode = AE_MODE_OFF / AWB mode not AUTO</strong></td> 504 <td></td> 505 <td></td> 506 <td></td> 507 </tr> 508 <tr> 509 <th>State</th> 510 <th>Transformation cause</th> 511 <th>New state</th> 512 <th>Notes</th> 513 </tr> 514 <tr> 515 <td>INACTIVE</td> 516 <td></td> 517 <td></td> 518 <td>AE/AWB disabled</td> 519 </tr> 520 <tr> 521 <td><strong>mode = AE_MODE_ON_* / AWB_MODE_AUTO</strong></td> 522 <td></td> 523 <td></td> 524 <td></td> 525 </tr> 526 <tr> 527 <th>State</th> 528 <th>Transformation cause</th> 529 <th>New state</th> 530 <th>Notes</th> 531 </tr> 532 <tr> 533 <td>INACTIVE</td> 534 <td>HAL initiates AE/AWB scan</td> 535 <td>SEARCHING</td> 536 <td></td> 537 </tr> 538 <tr> 539 <td>INACTIVE</td> 540 <td>AE/AWB_LOCK on</td> 541 <td>LOCKED</td> 542 <td>Values locked</td> 543 </tr> 544 <tr> 545 <td>SEARCHING</td> 546 <td>HAL finishes AE/AWB scan</td> 547 <td>CONVERGED</td> 548 <td>Good values, not changing</td> 549 </tr> 550 <tr> 551 <td>SEARCHING</td> 552 <td>HAL finishes AE scan</td> 553 <td>FLASH_REQUIRED</td> 554 <td>Converged but too dark without flash</td> 555 </tr> 556 <tr> 557 <td>SEARCHING</td> 558 <td>AE/AWB_LOCK on</td> 559 <td>LOCKED</td> 560 <td>Values locked</td> 561 </tr> 562 <tr> 563 <td>CONVERGED</td> 564 <td>HAL initiates AE/AWB scan</td> 565 <td>SEARCHING</td> 566 <td>Values locked</td> 567 </tr> 568 <tr> 569 <td>CONVERGED</td> 570 <td>AE/AWB_LOCK on</td> 571 <td>LOCKED</td> 572 <td>Values locked</td> 573 </tr> 574 <tr> 575 <td>FLASH_REQUIRED</td> 576 <td>HAL initiates AE/AWB scan</td> 577 <td>SEARCHING</td> 578 <td>Values locked</td> 579 </tr> 580 <tr> 581 <td>FLASH_REQUIRED</td> 582 <td>AE/AWB_LOCK on</td> 583 <td>LOCKED</td> 584 <td>Values locked</td> 585 </tr> 586 <tr> 587 <td>LOCKED</td> 588 <td>AE/AWB_LOCK off</td> 589 <td>SEARCHING</td> 590 <td>Values not good after unlock</td> 591 </tr> 592 <tr> 593 <td>LOCKED</td> 594 <td>AE/AWB_LOCK off</td> 595 <td>CONVERGED</td> 596 <td>Values good after unlock</td> 597 </tr> 598 <tr> 599 <td>LOCKED</td> 600 <td>AE_LOCK off</td> 601 <td>FLASH_REQUIRED</td> 602 <td>Exposure good, but too dark</td> 603 </tr> 604 <tr> 605 <td>All AE states</td> 606 <td>PRECAPTURE_START</td> 607 <td>PRECAPTURE</td> 608 <td>Start precapture sequence</td> 609 </tr> 610 <tr> 611 <td>PRECAPTURE</td> 612 <td>Sequence done, AE_LOCK off</td> 613 <td>CONVERGED</td> 614 <td>Ready for high-quality capture</td> 615 </tr> 616 <tr> 617 <td>PRECAPTURE</td> 618 <td>Sequence done, AE_LOCK on</td> 619 <td>LOCKED</td> 620 <td>Ready for high-quality capture</td> 621 </tr> 622 </table> 623 <h2 id="manual-control">Enabling manual control</h2> 624 <p>Several controls are also involved in configuring the device 3A blocks to allow 625 for direct application control.</p> 626 <p>The HAL model for 3A control is that for each request, the HAL inspects the 627 state of the 3A control fields. If any 3A routine is enabled, then that routine 628 overrides the control variables that relate to that routine, and these override 629 values are then available in the result metadata for that capture. So for 630 example, if auto-exposure is enabled in a request, the HAL should overwrite the 631 exposure, gain, and frame duration fields (and potentially the flash fields, 632 depending on AE mode) of the request. The list of relevant controls is:</p> 633 <table> 634 <tr> 635 <th>Control name</th> 636 <th>Unit</th> 637 <th>Notes</th> 638 </tr> 639 <tr> 640 <td>android.control.mode</td> 641 <td>enum: OFF, AUTO, USE_SCENE_MODE</td> 642 <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. 643 When set to AUTO, the individual algorithm controls in android.control.* are in effect, such as android.control.afMode. 644 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> 645 </tr> 646 <tr> 647 <td>android.control.afMode</td> 648 <td>enum</td> 649 <td>OFF means manual control of lens focusing through android.lens.focusDistance.</td> 650 </tr> 651 <tr> 652 <td>android.control.aeMode</td> 653 <td>enum</td> 654 <td>OFF means manual control of exposure/gain/frame duration through android.sensor.exposureTime / .sensitivity / .frameDuration</td> 655 </tr> 656 <tr> 657 <td>android.control.awbMode</td> 658 <td>enum</td> 659 <td>OFF means manual control of white balance. </td> 660 </tr> 661 </table> 662 663 </body> 664 </html> 665
