O gerenciamento e o uso da configuração da câmera e do sistema também foram atualizados no Extended View System (EVS) 1.1. Como o EVS 1.0 não fornece métodos para consultar as informações do dispositivo da câmera e a configuração do sistema, o desenvolvedor do aplicativo deve obter essas informações por conta própria. Por exemplo, o cliente deve ter dados de calibração da câmera se implementar alguns aplicativos de visão computacional.
Para aliviar essa circunstância, o EVS 1.1 estende um descritor de dispositivo de câmera com metadados de câmera e fornece vários métodos que permitem que os clientes obtenham informações de dispositivo de câmera e configuração do sistema.
import android.frameworks.cameraservice.device@2.0::CameraMetadata;
import android.frameworks.cameraservice.common@2.0::CameraMetadataType;
/**
* Structure describing the basic properties of an EVS camera, extended
* from its v1.0 declaration.
*
* The HAL is responsible for filling out this structure for each
* EVS camera in the system.
*/
struct CameraDesc {
@1.0::CameraDesc v1;
/**
* Store camera metadata such as lens characteristics.
*/
CameraMetadata metadata;
};
CameraDesc é estendido para ter metadados de dispositivo de câmera e esse tipo é importado de android.frameworks.cameraservice.device@2.0 . Essa escolha de design permite que os fornecedores usem camera_metadata_t em suas implementações e aproveitem as APIs definidas em ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS . O driver EVS pode usar esse tipo para identificar quais configurações de fluxo são compatíveis. Além disso, os fornecedores não podem usar seus próprios tipos de metadados para fornecer outras informações não definidas no Android , conforme explicado em ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS . O driver EVS pode usar esse tipo para identificar quais configurações de fluxo são suportadas
Abra um dispositivo de câmera com a configuração de fluxo desejada
import android.hardware.camera.device@3.2::Stream; /** * Get the IEvsCamera associated with a cameraId from a CameraDesc * * Given a camera's unique cameraId from CameraDesc, returns the * IEvsCamera interface associated with the specified camera. When * done using the camera, the caller may release it by calling closeCamera(). * * @param cameraId A unique identifier of the camera. * @param streamCfg A stream configuration the client wants to use. * @return evsCamera EvsCamera object associated with a given cameraId. */ openCamera_1_1(string cameraId, Stream streamCfg) generates (IEvsCamera evsCamera);
Um dos campos de metadados que o Android define é ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS . O driver EVS pode usar esse tipo para identificar quais configurações de fluxo suportadas por cada módulo de câmera. Por exemplo, a implementação de referência fornecida abaixo lista as informações de ou de cada configuração de stream suportada:
- ID da transmissão
- Largura
- Altura
- Direção (entrada ou saída)
- Taxa de quadros
Vários clientes em uma única instância HW de câmera
Se um cliente solicitar a abertura de um dispositivo de câmera já ativo, o gerenciador EVS compara uma configuração de fluxo solicitada com a configuração ativa. Se forem diferentes, o gerenciador EVS retorna um objeto IEvsCamera nulo. O cliente DEVE lidar adequadamente com essa possível falha.
Arquivo de configuração de referência
O arquivo de configuração de referência incluído no EVS 1.1 é escrito em XML e os fornecedores podem usar o arquivo DTD incluído (mostrado abaixo) para validar um arquivo de configuração de amostra (modificado) ou usar seu próprio arquivo se quiserem usar o mesmo formato. O arquivo DTD também fornece descrições detalhadas para cada elemento e atributo.
<?xml version='1.0' encoding='utf-8'?>
<!-- Copyright (C) 2019 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.
-->
<!-- Author : changyeon@google.com
Version: 1.0
-->
<!ELEMENT configuration (system,camera,display)>
<!-- System Configuration that contains below informations:
- The dimension of the vehicle.
- Number of cameras available to EVS.
- List of predefined use cases.
-->
<!ELEMENT system (dimension,num_cameras,supported_use_case*)>
<!-- The x, y, and z dimension of the vehicle in the unit of centimeters. Axes are defined at
https://source.android.com/docs/core/interaction/sensors/sensor-types#auto_axes
-->
<!ELEMENT dimension EMPTY>
<!ATTLIST dimension
x CDATA '0'
y CDATA '0'
z CDATA '0'
>
<!-- The number of cameras that are available to EVS on the vehicle.
This must be equal to the number of camera elements of the device element.
-->
<!ELEMENT num_cameras EMPTY>
<!ATTLIST num_cameras
value CDATA #REQUIRED
>
<!-- List of predefined use cases -->
<!ELEMENT supported_use_case (use_case)*>
<!-- Predefined configurations for each of listed use cases.
@attr id : Unique string identifier of this use case.
@attr camera : ID of either a single camera device or a camera group.
@attr stream_id: Preferred stream configuration of camera device/group
that is set by camera attribute.
-->
<!ELEMENT use_case EMPTY>
<!ATTLIST use_case
id CDATA #REQUIRED
camera CDATA #REQUIRED
stream_id CDATA #REQUIRED
>
<!-- Device descriptions -->
<!ELEMENT camera (group|device)*>
<!-- Camera group descriptor
@attr group_id : Unique logical camera group identifier. Camera device use this to be
a member of the group.
@attr device_id : Comma-separated list of unique camera identifiers of member camera
devices.
@attr synchronized: Boolean field that tells whether or not this camera is synchronized
with other cameras in the same group. This will be ineffective if
there is a single camera in the group or a group is invalid.
-->
<!ELEMENT group (caps)>
<!ATTLIST group
group_id CDATA #REQUIRED
device_id CDATA #REQUIRED
synchronized CDATA #REQUIRED
>
<!-- Please note that a camera may have stream configurations. If it has, all stream
configurations must be supported by each camera device in the group.
-->
<!-- Camera device descriptor
@attr id : Unique camera identifier.
@attr position : Must be one of front, rear, left, or right.
-->
<!ELEMENT device (caps,characteristics*)>
<!ATTLIST device
id CDATA #REQUIRED
position CDATA #REQUIRED
>
<!-- Camera metadata that contains:
- A list of supported controls.
- A list of supported stream configurations.
-->
<!ELEMENT caps (supported_controls|stream)*>
<!-- A list of supported controls.
This must be a subset of android.hardware.automotive.evs@1.1::CameraParam.
-->
<!ELEMENT supported_controls EMPTY>
<!ATTLIST supported_controls
value CDATA #REQUIRED
>
<!-- A list of supported output sizes. -->
<!ELEMENT stream EMPTY>
<!ATTLIST stream
id CDATA #REQUIRED
width CDATA #REQUIRED
height CDATA #REQUIRED
format CDATA #REQUIRED
>
<!-- Camera module characteristics including its optics and imaging sensor. -->
<!ELEMENT characteristics (parameter)*>
<!ELEMENT parameter EMPTY>
<!-- A name of camera characteristic. This must be a subset of
android.hardware.automotive.evs@1.1::CameraCharacteristics.
-->
<!ATTLIST parameter
name CDATA #REQUIRED
type CDATA #REQUIRED
size CDATA #REQUIRED
value CDATA #REQUIRED
>
<!-- Available display devices -->
<!ELEMENT display (display_device)*>
<!-- Display device descriptor
@attr id : Unique display identifier.
@attr position: Display mount location.
-->
<!ELEMENT display_device (supported_formats)*>
<!ATTLIST display_device
id CDATA #REQUIRED
position CDATA #REQUIRED
>
<!-- A list of supported input data formats.
@attr value: A comma separated list of input data formats
-->
<!ELEMENT supported_formats EMPTY>
<!ATTLIST supported_formats
value CDATA #REQUIRED
>
Um arquivo de configuração de exemplo é mostrado abaixo (o exemplo contém dados numéricos fictícios).
<?xml version='1.0' encoding='utf-8'?>
<!-- Copyright (C) 2019 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.
-->
<!-- Extended View System Example Configuration
Android Automotive axes are used to define coordinates.
See https://source.android.com/docs/core/interaction/sensors/sensor-types#auto_axes
Use evs_configuration.dtd with xmllint tool, to validate XML configuration file
-->
<configuration>
<!-- system configuration -->
<system>
<!-- reference dimension of the vehicle in the unit of centimeters -->
<dimension x='200' y='400' z='100' />
<!-- number of cameras available to EVS -->
<num_cameras value='2'/>
<!-- list of supported use cases -->
<supported_use_case>
<!-- use case configuration -->
<use_case
id='rear_view'
camera='/dev/video1'
stream_id='1'
/>
<!-- use case configuration -->
<use_case
id='surround_view'
camera='group1'
stream_id='0'
/>
</supported_use_case>
</system>
<!-- camera device information -->
<camera>
<!-- camera group 0 -->
<group group_id='group0'
device_id='/dev/video1,/dev/video2'
synchronized='false'
>
<caps>
<stream id='0' width='640' height='360' format='V4L2_PIX_UYUV'/>
</caps>
</group>
<!-- camera device starts -->
<device id='/dev/video1' position='rear'>
<caps>
<!-- list of supported controls -->
<supported_controls
value='BRIGHTNESS,
CONTRAST,
AUTO_WHITE_BALANCE,
WHITE_BALANCE_TEMPERATURE,
SHARPNESS,
AUTO_EXPOSURE,
ABSOLUTE_EXPOSURE,
AUTO_FOCUS,
ABSOLUTE_ZOOM'
/>
<!-- list of supported stream configurations -->
<stream id='0' width='1280' height='1080' format='V4L2_PIX_NV21'/>
<stream id='1' width='1280' height='1080' format='V4L2_PIX_YUYV'/>
<stream id='2' width='1280' height='1080' format='V4L2_PIX_UYUV'/>
<stream id='3' width='640' height='360' format='V4L2_PIX_NV21'/>
<stream id='4' width='640' height='360' format='V4L2_PIX_YUYV'/>
<stream id='5' width='640' height='360' format='V4L2_PIX_UYUV'/>
<stream id='6' width='320' height='240' format='V4L2_PIX_NV21'/>
<stream id='7' width='320' height='240' format='V4L2_PIX_YUYV'/>
<stream id='8' width='320' height='240' format='V4L2_PIX_UYUV'/>
</caps>
<!-- list of parameters -->
<characteristics>
<!-- Lens distortion information. See
https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics.html#LENS_DISTORTION
-->
<parameter
name='LENS_DISTORTION'
type='float'
size='5'
value='0.0,0.0,0.0,0.0,0.0'
/>
<!-- Camera intrinsic calibration matrix. See
https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics.html#LENS_INTRINSIC_CALIBRATION
-->
<parameter
name='LENS_INTRINSIC_CALIBRATION'
type='float'
size='5'
value='0.0,0.0,0.0,0.0,0.0'
/>
<!-- Camera pose translation and rotation. See
https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics.html#LENS_POSE_TRANSLATION
https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics.html#LENS_POSE_ROTATION
-->
<parameter
name='LENS_POSE_TRANSLATION'
type='float'
size='3'
value='0.0,0.0,0.0'
/>
<parameter
name='LENS_POSE_ROTATION'
type='float'
size='4'
value='0.0,0.0,0.0,0.0'
/>
</characteristics>
</device>
<device id='/dev/video2' position='front'>
<caps>
<!-- list of supported stream configurations -->
<stream id='0' width='1280' height='1080' format='V4L2_PIX_NV21'/>
</caps>
</device>
</camera>
<!-- display device starts -->
<display>
<display_device id='display0' position='driver'>
<!-- list of supported input formats
This must be a subset of android_pixel_format_t enum.
-->
<supported_formats
value='RGBA_8888,
YUYV,
UYVY'
/>
</display_device>
</display>
</configuration>