《V4L2 spec 中文 v0.625》pdf

【实例截图】

【核心代码】

目 录
Chapter 1. 通用 API（Common API Elements） .............................................................................................1
1.1. 打开和关闭设备（Opening and Closing Devices）.......................................................................1
1.1.1. 设备命名(Device Naming)....................................................................................................1
1.1.2. 相关设备(Related Devices) ..................................................................................................2
1.1.3. 并发打开(Multiple Opens)...................................................................................................3
1.1.4. 共享数据流(Shared Data Streams) ......................................................................................3
1.1.5. 函数(Functions) ....................................................................................................................3
1.2. 功能查询(Querying Capabilities) ....................................................................................................3
1.3. 应用程序的优先级(Application Priority)........................................................................................4
1.4. 视频输入/输出(Video Inputs and Outputs)....................................................................................4
1.5. 音频输入/输出(Audio Inputs and Outputs)....................................................................................5
1.6. 高频头和调制器（Tuners and Modulators）................................................................................8
1.6.1. 高频头(Tuners) .....................................................................................................................8
1.6.2. 调制器（Modulators）........................................................................................................9
1.6.3. 无线频率(Radio Frequency).................................................................................................9
1.6.4. 卫星接收器(Satellite Receivers).........................................................................................10
1.7. 视频标准(Video Standards) ..........................................................................................................10
1.8. 用户控制(User Controls) ...............................................................................................................14
1.9. 扩展控制(Extended Controls) .......................................................................................................20
1.9.1. 介绍(Introduction)..............................................................................................................20
1.9.2. 扩展类控制 API(The Extended Control API） ...................................................................21
1.9.3. 扩展 control 值的枚举(Enumeration Extended Controls).................................................21
1.9.4. 创建 control 面板(Creating Control Panels).......................................................................22
1.9.5. MPEG Control Reference ....................................................................................................22
1.9.6. 摄像头 control 参考(Camera Control Reference)..............................................................27
1.10. 数据格式(Data Formats) .............................................................................................................27
1.10.1. 协商数据格式(Data Format Negotiation)........................................................................27
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1.10.2. 枚举图片格式(Image Format Enumeration) ...................................................................28
1.11. 图片修剪，插入和缩放(Image Cropping，Insertion and Scalling)...........................................28
1.11.1. 修剪结构(Cropping Structures)........................................................................................29
1.11.2. 缩放调整(Scaling Adjustments) .......................................................................................30
1.11.3. 样例程序(Examples).........................................................................................................30
1.12. Streaming 参数(Streaming Parameters)......................................................................................34
Notes........................................................................................................................................................34
Chapter 2. 图像格式(Image Formats) ............................................................................................................35
2.1. 标准图片格式(Standard Image Formats) .....................................................................................36
2.2. 色彩空间(Colorspaces)..................................................................................................................37
2.3. 索引格式(Indexed Format)............................................................................................................40
2.4. RGB 格式(RGB Formats) ................................................................................................................40
2.5. YUV 格式(YUV Formats) ................................................................................................................43
2.6. 压缩格式(Compressed Formats)...................................................................................................44
2.7. 保留的格式标识符(Reserved Format Identifiers) ........................................................................45
Chapter 3. 输入/输出(Input/Output).............................................................................................................46
3.1. 读和写(Read/Write) ......................................................................................................................46
3.2. 流式 I/O(内存映射缓冲区)(Streaming I/O(Memory Mapping))..................................................47
3.3. 流 I/O(用户空间缓冲区(用户指针))(Streaming I/O(User Pointers)) ...........................................50
3.4. 异步 I/O(Asynchronous I/O)..........................................................................................................52
3.5. 缓冲(Buffers)..................................................................................................................................52
3.5.1. 时码(Timecodes) ................................................................................................................55
3.6. field 次序(Field Order)...................................................................................................................55
Notes........................................................................................................................................................56
Chapter 4. 接口(Interface)..............................................................................................................................57
4.1. 视频采集接口(Video Capture Interface) ........................................................................................57
4.1.1. 查询设备属性(Querying Capabilities) .................................................................................57
4.1.2. 附加功能(Supplemental Functions).....................................................................................57
4.1.3. 图片格式协商(Image Format Negotiation) .........................................................................58
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4.1.4. 读取图片(Reading Images)...................................................................................................58
4.2. Video Overlay Interface ....................................................................................................................58
4.2.1. 查询设备属性(Querying Capabilities）...............................................................................59
4.2.2. 附加功能(Supplemental Functions).....................................................................................59
4.2.3. 设置(Setup)...........................................................................................................................59
4.2.4．Overlay 窗口（Overlay Window）.....................................................................................59
4.2.5. 使能 overlay（Enabling Overlay）.......................................................................................60
4.3. 视频输出接口(Video Output Interface) .........................................................................................61
4.3.1. 设备功能查询(Querying Capabilities) .................................................................................61
4.3.2. 附加功能（Supplemental Functions） ...............................................................................61
4.3.3. 图片格式协商（Images Format Negotiation） ..................................................................61
4.3.4. 写图片（Writing Image）....................................................................................................61
4.4. 视频输出 overlay 接口（Video Output Overlay Interface）.........................................................62
4.4.1. 设备功能查询（Querying Capabilities）............................................................................62
4.4.2. 帧缓冲（Framebuffer） ......................................................................................................62
4.4.3. overlay 窗口和缩放...............................................................................................................63
4.4.4. 使能 overlay（Enabling Overlay）.......................................................................................63
4.5. 编码接口（Codec Interface）........................................................................................................64
4.6. 特效设备接口（Effect Devices Interface）....................................................................................64
4.7. 原始 VBI 数据接口（Raw VBI Data Interface）.............................................................................64
4.8. 分离 VBI 数据接口（Sliced VBI Data Interface） ..........................................................................64
4.9. 图文电视接口（Teltext Interface） ...............................................................................................64
4.10. 无线电接口（Radio Interface）...................................................................................................65
4.11. 无线数据广播系统（Radio Data Interface） ..............................................................................65
Notes........................................................................................................................................................65
Chapter 5. 驱动编写.......................................................................................................................................66