1# Multimedia<a name="EN-US_TOPIC_0000001078026808"></a> 2 3## Introduction<a name="section11660541593"></a> 4 5The multimedia subsystem provides a set of simple and easy-to-use APIs for you to access the system and media resources. 6 7This subsystem offers various media services covering audio, videos, and cameras, which provide the following capabilities: 8 9- Audio playback and recording 10- Video playback and recording 11- Photographing and recording \(with cameras\) 12 13## System Architecture<a name="section11660541594"></a> 14 15**Figure 1** Architecture of the multimedia subsystem<a name="fig99659301300"></a> 16 17 18 19- **Media**: provides playback and recording APIs for applications, and invokes the Gstreamer, Histreamer, or other engines through cross-process calling or direct calling. 20 - For the mini system, the media component invokes Histreamer to support audio playback. 21 - For the small system, the media component invokes recorder_lite to support audio/video recording and invokes player_lite by default to support audio/video playback. If the system variable **debug.media_service.histreamer** is set to **1**, the component invokes Histreamer to support audio/video playback. For details, see [syspara Module](https://gitee.com/openharmony/docs/blob/master/en/device-dev/subsystems/subsys-boot-init-sysparam.md) or [syspara_lite](https://gitee.com/openharmony/startup_syspara_lite). 22 - For the standard system, the media component invokes Gstreamer to support audio/video playback and recording. 23- **Audio**: supports audio input and output, policy management, and audio focus management. 24- **Camera**: provides camera operation APIs for preview, photographing, and video recording. 25- **Image**: supports encoding and decoding of common image formats. 26- **MediaLibrary**: supports local and distributed media data access management. 27- **Histreamer**: a lightweight media engine that supports file/network streaming media input, audio/video decoding and playback, audio/video encoding and recording, and plugin extension. 28- **Gstreamer**: an open-source GStreamer engine that supports streaming media, audio and video playback, and recording. 29 30## Directory Structure<a name="section161941989596"></a> 31 32The structure of the repository directory is as follows: 33 34``` 35/foundation/multimedia # Service code 36├── audio_lite # Audio module for the small system 37│ ├── figures # Architecture and process figures of the audio module for the small system 38│ ├── frameworks # Audio framework implementation for the small system 39│ └── interfaces # Audio module APIs for the small system 40├── audio_standard # Audio module for the standard system 41│ ├── figures # Architecture and process figures of the audio module for the standard system 42│ ├── frameworks # Audio framework implementation for the standard system 43│ ├── interfaces # Audio module APIs for the standard system 44│ ├── sa_profile # Audio service profile for the standard system 45│ └── services # Audio service implementation for the standard system 46├── camera_lite # Camera module for the small system 47│ ├── figures # Architecture and process figures of the camera module for the small system 48│ ├── frameworks # Camera framework implementation for the small system 49│ └── interfaces # Camera module APIs for the small system 50├── camera_standard # Camera module for the standard system 51│ ├── figures # Architecture and process figures of the camera module for the standard system 52│ ├── frameworks # Camera framework implementation for the standard system 53│ └── interfaces # Camera module APIs for the standard system 54├── media_lite # Playback and recording module for the small system 55│ ├── figures # Architecture and process figures of the playback and recording module for the small system 56│ ├── frameworks # Playback and recording framework implementation for the small system 57│ ├── interfaces # Playback and recording module APIs for the small system 58│ └── services # Playback and recording service implementation for the small system 59├── media_standard # Playback and recording module for the standard system 60│ ├── figures # Architecture and process figures of the playback and recording module for the standard system 61│ ├── frameworks # Playback and recording framework implementation for the standard system 62│ └── interfaces # Playback and recording module APIs for the standard system 63├── histreamer # Histreamer engine 64│ └── engine # Media engine 65│ ├── player # Encapsulated player 66│ ├── foundation # Basic tools 67│ ├── pipeline # Pipeline framework 68│ └── plugin # Plugin framework 69│ └── plugins # Platform software plugins 70└── utils # Subsystem utility module 71 └── lite # Utility module for the small system 72 ├── figures # Architecture and process figures of the utility module for the small system 73 ├── hals # Hardware abstraction interfaces of the subsystem for the small system 74 ├── interfaces # Utility module APIs for the standard system 75 └── src # Utility module framework implementation for the small system 76``` 77 78## Constraints<a name="section119744591305"></a> 79 80Hardware-based decoding and encoding functions of audio and video data are device-specific. 81 82## Usage Guidelines<a name="section1312121216216"></a> 83 84You can use the APIs in any of the provided classes based on your development requirements. 85 86- For details about how to call media APIs to implement the video recording, preview, and playback, see [Multimedia Development Guide](../application-dev/media). 87- For a simple player, use **Player** and **Recorder** classes to quickly implement the playback and recording features. 88- The **CameraKit** class provides a group of effective methods for controlling a camera, which facilitates the camera development. 89- You can create a **CameraKit** object and register various callbacks to respond to many events in the multimedia module. Then, create a **Camera** object to operate camera resources, for example, to start preview, recording, and stream capturing, and set related parameters. 90 91## Installation<a name="section11914418405"></a> 92 93Load the kernel and related drivers before installing the repository. For details, see readme files of kernel and driver subsystems. 94 95## Repositories Involved<a name="section1371113476307"></a> 96 97[multimedia\_camera\_lite](https://gitee.com/openharmony/multimedia_camera_lite) 98 99[multimedia\_audio\_lite](https://gitee.com/openharmony/multimedia_audio_lite) 100 101[multimedia\_media\_lite](https://gitee.com/openharmony/multimedia_media_lite) 102 103[multimedia\_utils\_lite](https://gitee.com/openharmony/multimedia_utils_lite) 104 105[multimedia\_histreamer](https://gitee.com/openharmony/multimedia_histreamer) 106 107[multimedia\_camera\_standard](https://gitee.com/openharmony/multimedia_camera_standard) 108 109[multimedia\_audio\_standard](https://gitee.com/openharmony/multimedia_audio_standard) 110 111[multimedia\_media\_standard](https://gitee.com/openharmony/multimedia_media_standard) 112
