1# Use Case<a name="EN-US_TOPIC_0000001055301733"></a> 2 3This use case takes **camera\_sample** \(contained in the source code\) as an example for photographing, recording, and previewing on the development board. 4 5- You can obtain source code of the sample from **applications/sample/camera/media/camera\_sample.cpp**. 6- 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). 7 8 > **NOTE**<br/> 9 >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. 10 >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**. 11 12- 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**. 13 14 Modify the first **output\_dir** in the source code path **applications/sample/camera/media/BUILD.gn**. 15 16 - Before: **output\_dir = "$root\_out\_dir/dev\_ools"** 17 - After: **output\_dir = "$root\_out\_dir/"** 18 19 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. 20 21 > **NOTICE**<br/> 22 >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. 23 >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. 24 25- Perform the following steps to run the sample: 26 271. 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. 28 29 **Figure 1** Starting camera\_sample<a name="fig380985885020"></a> 30  31 32 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. 33 342. Press **1** to take a photo in JPG format. The photo is saved in the **/sdcard** directory and named **Capture\***. 35 36 **Figure 2** Serial port logs displayed after the photographing command is executed<a name="fig17819185018384"></a> 37  38 39 To view the saved file, exit the program and enter the file system. To start the program again, return to the previous step. 40 41 **Figure 3** Saved files<a name="fig166391743154619"></a> 42  43 443. 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. 45 46 **Figure 4** Serial port logs displayed after the recording command is executed<a name="fig6340814174317"></a> 47  48 494. Press **3** to start preview. The preview is displayed on the screen. Press **S** to stop preview. 50 51 **Figure 5** Serial port logs displayed after the preview command is executed<a name="fig9658148124414"></a> 52  53 54 The following figure shows the preview. 55 56 **Figure 6** Preview effect<a name="fig24541759597"></a> 57  58 595. Press **Q** to exit. 60 61 **Figure 7** Serial port logs displayed after the exit command is executed<a name="fig1755682174514"></a> 62  63 64 65
