diff --git a/include/hardware/camera3.h b/include/hardware/camera3.h index f4bae138..af918562 100644 --- a/include/hardware/camera3.h +++ b/include/hardware/camera3.h @@ -42,7 +42,8 @@ * S2. Startup and operation sequencing * S3. Operational modes * S4. 3A modes and state machines - * S5. Error management + * S5. Cropping + * S6. Error management */ /** @@ -744,7 +745,162 @@ */ /** - * S5. Error management: + * S5. Cropping: + * + * Cropping of the full pixel array (for digital zoom and other use cases where + * a smaller FOV is desirable) is communicated through the + * ANDROID_SCALER_CROP_REGION setting. This is a per-request setting, and can + * change on a per-request basis, which is critical for implementing smooth + * digital zoom. + * + * The region is defined as a rectangle (x, y, width, height), with (x, y) + * describing the top-left corner of the rectangle. The rectangle is defined on + * the coordinate system of the sensor active pixel array, with (0,0) being the + * top-left pixel of the active pixel array. Therefore, the width and height + * cannot be larger than the dimensions reported in the + * ANDROID_SENSOR_ACTIVE_PIXEL_ARRAY static info field. The minimum allowed + * width and height are reported by the HAL through the + * ANDROID_SCALER_MAX_DIGITAL_ZOOM static info field, which describes the + * maximum supported zoom factor. Therefore, the minimum crop region width and + * height are: + * + * {width, height} = + * { floor(ANDROID_SENSOR_ACTIVE_PIXEL_ARRAY[0] / + * ANDROID_SCALER_MAX_DIGITAL_ZOOM), + * floor(ANDROID_SENSOR_ACTIVE_PIXEL_ARRAY[1] / + * ANDROID_SCALER_MAX_DIGITAL_ZOOM) } + * + * If the crop region needs to fulfill specific requirements (for example, it + * needs to start on even coordinates, and its width/height needs to be even), + * the HAL must do the necessary rounding and write out the final crop region + * used in the output result metadata. Similarly, if the HAL implements video + * stabilization, it must adjust the result crop region to describe the region + * actually included in the output after video stabilization is applied. In + * general, a camera-using application must be able to determine the field of + * view it is receiving based on the crop region, the dimensions of the image + * sensor, and the lens focal length. + * + * Since the crop region applies to all streams, which may have different aspect + * ratios than the crop region, the exact sensor region used for each stream may + * be smaller than the crop region. Specifically, each stream should maintain + * square pixels and its aspect ratio by minimally further cropping the defined + * crop region. If the stream's aspect ratio is wider than the crop region, the + * stream should be further cropped vertically, and if the stream's aspect ratio + * is narrower than the crop region, the stream should be further cropped + * horizontally. + * + * In all cases, the stream crop must be centered within the full crop region, + * and each stream is only either cropped horizontally or vertical relative to + * the full crop region, never both. + * + * For example, if two streams are defined, a 640x480 stream (4:3 aspect), and a + * 1280x720 stream (16:9 aspect), below demonstrates the expected output regions + * for each stream for a few sample crop regions, on a hypothetical 3 MP (2000 x + * 1500 pixel array) sensor. + * + * Crop region: (500, 375, 1000, 750) (4:3 aspect ratio) + * + * 640x480 stream crop: (500, 375, 1000, 750) (equal to crop region) + * 1280x720 stream crop: (500, 469, 1000, 562) (marked with =) + * + * 0 1000 2000 + * +---------+---------+---------+----------+ + * | Active pixel array | + * | | + * | | + * + +-------------------+ + 375 + * | | | | + * | O===================O | + * | I 1280x720 stream I | + * + I I + 750 + * | I I | + * | O===================O | + * | | | | + * + +-------------------+ + 1125 + * | Crop region, 640x480 stream | + * | | + * | | + * +---------+---------+---------+----------+ 1500 + * + * Crop region: (500, 375, 1333, 750) (16:9 aspect ratio) + * + * 640x480 stream crop: (666, 375, 1000, 750) (marked with =) + * 1280x720 stream crop: (500, 375, 1333, 750) (equal to crop region) + * + * 0 1000 2000 + * +---------+---------+---------+----------+ + * | Active pixel array | + * | | + * | | + * + +---O==================O---+ + 375 + * | | I 640x480 stream I | | + * | | I I | | + * | | I I | | + * + | I I | + 750 + * | | I I | | + * | | I I | | + * | | I I | | + * + +---O==================O---+ + 1125 + * | Crop region, 1280x720 stream | + * | | + * | | + * +---------+---------+---------+----------+ 1500 + * + * Crop region: (500, 375, 750, 750) (1:1 aspect ratio) + * + * 640x480 stream crop: (500, 469, 750, 562) (marked with =) + * 1280x720 stream crop: (500, 543, 750, 414) (marged with #) + * + * 0 1000 2000 + * +---------+---------+---------+----------+ + * | Active pixel array | + * | | + * | | + * + +--------------+ + 375 + * | O==============O | + * | ################ | + * | # # | + * + # # + 750 + * | # # | + * | ################ 1280x720 | + * | O==============O 640x480 | + * + +--------------+ + 1125 + * | Crop region | + * | | + * | | + * +---------+---------+---------+----------+ 1500 + * + * And a final example, a 1024x1024 square aspect ratio stream instead of the + * 480p stream: + * + * Crop region: (500, 375, 1000, 750) (4:3 aspect ratio) + * + * 1024x1024 stream crop: (625, 375, 750, 750) (marked with #) + * 1280x720 stream crop: (500, 469, 1000, 562) (marked with =) + * + * 0 1000 2000 + * +---------+---------+---------+----------+ + * | Active pixel array | + * | | + * | 1024x1024 stream | + * + +--###############--+ + 375 + * | | # # | | + * | O===================O | + * | I 1280x720 stream I | + * + I I + 750 + * | I I | + * | O===================O | + * | | # # | | + * + +--###############--+ + 1125 + * | Crop region | + * | | + * | | + * +---------+---------+---------+----------+ 1500 + * + */ + +/** + * S6. Error management: * * Camera HAL device ops functions that have a return value will all return * -ENODEV / NULL in case of a serious error. This means the device cannot