xref: /docs/en/device-dev/guide/device-camera-control-example.md

# Use Case<a name="EN-US_TOPIC_0000001055301733"></a>

This use case takes **camera\_sample** \(contained in the source code\) as an example for photographing, recording, and previewing on the development board.

-   You can obtain source code of the sample from **applications/sample/camera/media/camera\_sample.cpp**.
-   Before running the sample camera, you need to compile, burn, and run the image. For details, see  [Quick Start Overview](../quick-start/quickstart-overview.md).

    >![](../public_sys-resources/icon-note.gif) **NOTE**<br/>
    >After the development board is started, the home screen is loaded and displayed above the media layer by default. To prevent covering **camera\_sample**, you should remove the home screen during compilation or packaging.
    >How to Remove: In **build/lite/components/applications.json**, comment out or delete the **//applications/sample/camera/launcher:launcher\_hap** line from the **target** field of **camera\_sample\_app**.

-   The compilation result of the sample code is stored in **out/hi3516dv300/ipcamera\_hi3516dv300\_liteos/dev\_tools/bin**. To ensure that the code can be executed on the development board, you can copy the file to a TF card through a card reader, or modify the compilation script of **camera\_sample** to copy the compilation result to **rootfs.img**.

    Modify the first **output\_dir** in the source code path **applications/sample/camera/media/BUILD.gn**.

    -   Before: **output\_dir = "$root\_out\_dir/dev\_ools"**
    -   After: **output\_dir = "$root\_out\_dir/"**

    Recompile the source code repository and burn the code into the development board. Then you can find the **camera\_sample** file in the **bin** directory of the board.

    >![](../public_sys-resources/icon-notice.gif) **NOTICE**<br/>
    >You should insert a TF card \(up to 128 GB supported\) for photographing and video recording before system startup. This way, the TF card will be automatically mounted to the **/sdcard** directory. If you insert the TF card after the system is started, you have to manually mount the TF card.
    >To view the photos and videos in the TF card, copy them to a computer. If you just want to preview photos and videos, you do not need to insert a TF card.

-   Perform the following steps to run the sample:

1.  Run the **cd** command to go to the end path of the executable program and start **camera\_sample** by running the command in the following figure.

    **Figure 1** Starting camera\_sample<a name="fig380985885020"></a>  
    ![](figures/starting-camera_sample.png "starting-camera_sample")

    The control commands are displayed as shown in the preceding figure. Press **S** to stop the current operation \(including video recording and preview\), and press **Q** to exit the program.

2.  Press **1** to take a photo in JPG format. The photo is saved in the **/sdcard** directory and named **Capture\***.

    **Figure 2** Serial port logs displayed after the photographing command is executed<a name="fig17819185018384"></a>  
    ![](figures/serial-port-logs-displayed-after-the-photographing-command-is-executed.png "serial-port-logs-displayed-after-the-photographing-command-is-executed")

    To view the saved file, exit the program and enter the file system. To start the program again, return to the previous step.

    **Figure  3** Saved files<a name="fig166391743154619"></a>  
    ![](figures/saved-files.png "saved-files")

3.  Press **2** to start recording. The video file is in MP4 format and saved in the **/sdcard** directory with the name **Record\***. Press **S** to stop recording.

    **Figure 4** Serial port logs displayed after the recording command is executed<a name="fig6340814174317"></a>  
    ![](figures/serial-port-logs-displayed-after-the-recording-command-is-executed.png "serial-port-logs-displayed-after-the-recording-command-is-executed")

4.  Press **3** to start preview. The preview is displayed on the screen. Press **S** to stop preview.

    **Figure 5** Serial port logs displayed after the preview command is executed<a name="fig9658148124414"></a>  
    ![](figures/serial-port-logs-displayed-after-the-preview-command-is-executed.png "serial-port-logs-displayed-after-the-preview-command-is-executed")

    The following figure shows the preview.

    **Figure 6** Preview effect<a name="fig24541759597"></a>  
    ![](figures/preview-effect.jpg "preview-effect")

5.  Press **Q** to exit.

    **Figure 7** Serial port logs displayed after the exit command is executed<a name="fig1755682174514"></a>  
    ![](figures/serial-port-logs-displayed-after-the-exit-command-is-executed.png "serial-port-logs-displayed-after-the-exit-command-is-executed")