1、库的导出符号表——audio_effect_library_t

audio_effect_library_t的定义在hardware/libhardware/include/hardware/audio_effect.h中。

这个结构体在Android4.3+时有发生变化，query_num_effects()和query_effect()被删除。

如果希望做库兼容性，需要检测EFFECT_LIBRARY_API_VERSION，当其为

#ifEFFECT_API_VERSION_MAJOR(EFFECT_LIBRARY_API_VERSION) > 2时query_num_effects()和query_effect()不复存在。

typedef struct audio_effect_library_s {// tag must be initialized to AUDIO_EFFECT_LIBRARY_TAGuint32_t tag;// Version of the effect library API : 0xMMMMmmmm MMMM: Major, mmmm: minoruint32_t version;// Name of this libraryconst char *name;// Author/owner/implementor of the libraryconst char *implementor;////    Function:        query_num_effects////    Description:    Returns the number of different effects exposed by the//          library. Each effect must have a unique effect uuid (see//          effect_descriptor_t). This function together with EffectQueryEffect()//          is used to enumerate all effects present in the library.////    Input/Output://          pNumEffects:    address where the number of effects should be returned.////    Output://        returned value:    0          successful operation.//                          -ENODEV     library failed to initialize//                          -EINVAL     invalid pNumEffects//        *pNumEffects:     updated with number of effects in library//int32_t (*query_num_effects)(uint32_t *pNumEffects);////    Function:        query_effect////    Description:    Returns the descriptor of the effect engine which index is//          given as argument.//          See effect_descriptor_t for details on effect descriptors.//          This function together with EffectQueryNumberEffects() is used to enumerate all//          effects present in the library. The enumeration sequence is://              EffectQueryNumberEffects(&num_effects);//              for (i = 0; i < num_effects; i++)//                  EffectQueryEffect(i,...);////    Input/Output://          index:          index of the effect//          pDescriptor:    address where to return the effect descriptor.////    Output://        returned value:    0          successful operation.//                          -ENODEV     library failed to initialize//                          -EINVAL     invalid pDescriptor or index//                          -ENOSYS     effect list has changed since last execution of//                                      EffectQueryNumberEffects()//                          -ENOENT     no more effect available//        *pDescriptor:     updated with the effect descriptor.//int32_t (*query_effect)(uint32_t index,effect_descriptor_t *pDescriptor);////    Function:        create_effect////    Description:    Creates an effect engine of the specified implementation uuid and//          returns an effect control interface on this engine. The function will allocate the//          resources for an instance of the requested effect engine and return//          a handle on the effect control interface.////    Input://          uuid:    pointer to the effect uuid.//          sessionId:  audio session to which this effect instance will be attached. All effects//              created with the same session ID are connected in series and process the same signal//              stream. Knowing that two effects are part of the same effect chain can help the//              library implement some kind of optimizations.//          ioId:   identifies the output or input stream this effect is directed to at audio HAL.//              For future use especially with tunneled HW accelerated effects////    Input/Output://          pHandle:        address where to return the effect interface handle.////    Output://        returned value:    0          successful operation.//                          -ENODEV     library failed to initialize//                          -EINVAL     invalid pEffectUuid or pHandle//                          -ENOENT     no effect with this uuid found//        *pHandle:         updated with the effect interface handle.//int32_t (*create_effect)(const effect_uuid_t *uuid,int32_t sessionId,int32_t ioId,effect_handle_t *pHandle);////    Function:        release_effect////    Description:    Releases the effect engine whose handle is given as argument.//          All resources allocated to this particular instance of the effect are//          released.////    Input://          handle:         handle on the effect interface to be released.////    Output://        returned value:    0          successful operation.//                          -ENODEV     library failed to initialize//                          -EINVAL     invalid interface handle//int32_t (*release_effect)(effect_handle_t handle);////    Function:        get_descriptor////    Description:    Returns the descriptor of the effect engine which implementation UUID is//          given as argument.////    Input/Output://          uuid:           pointer to the effect uuid.//          pDescriptor:    address where to return the effect descriptor.////    Output://        returned value:    0          successful operation.//                          -ENODEV     library failed to initialize//                          -EINVAL     invalid pDescriptor or uuid//        *pDescriptor:     updated with the effect descriptor.//int32_t (*get_descriptor)(const effect_uuid_t *uuid,effect_descriptor_t *pDescriptor);
} audio_effect_library_t;

示例：

__attribute__ ((visibility ("default")))
audio_effect_library_t AUDIO_EFFECT_LIBRARY_INFO_SYM = {tag : AUDIO_EFFECT_LIBRARY_TAG,version : EFFECT_LIBRARY_API_VERSION,name : "Downmix Library",implementor : "The Android Open Source Project",create_effect : DownmixLib_Create,release_effect : DownmixLib_Release,get_descriptor : DownmixLib_GetDescriptor,
};

此处定义了创建和销毁的方法，但是作为效果链，怎么可能连个process处理都没有，稍安勿躁。

2、接口定义——effect_handle_t

这里，process和command都出现了。

typedef struct effect_interface_s **effect_handle_t;
struct effect_interface_s {////    Function:       process////    Description:    Effect process function. Takes input samples as specified//          (count and location) in input buffer descriptor and output processed//          samples as specified in output buffer descriptor. If the buffer descriptor//          is not specified the function must use either the buffer or the//          buffer provider function installed by the EFFECT_CMD_SET_CONFIG command.//          The effect framework will call the process() function after the EFFECT_CMD_ENABLE//          command is received and until the EFFECT_CMD_DISABLE is received. When the engine//          receives the EFFECT_CMD_DISABLE command it should turn off the effect gracefully//          and when done indicate that it is OK to stop calling the process() function by//          returning the -ENODATA status.////    NOTE: the process() function implementation should be "real-time safe" that is//      it should not perform blocking calls: malloc/free, sleep, read/write/open/close,//      pthread_cond_wait/pthread_mutex_lock...////    Input://          self:       handle to the effect interface this function//              is called on.//          inBuffer:   buffer descriptor indicating where to read samples to process.//              If NULL, use the configuration passed by EFFECT_CMD_SET_CONFIG command.////          outBuffer:   buffer descriptor indicating where to write processed samples.//              If NULL, use the configuration passed by EFFECT_CMD_SET_CONFIG command.////    Output://        returned value:    0 successful operation//                          -ENODATA the engine has finished the disable phase and the framework//                                  can stop calling process()//                          -EINVAL invalid interface handle or//                                  invalid input/output buffer descriptionint32_t (*process)(effect_handle_t self,audio_buffer_t *inBuffer,audio_buffer_t *outBuffer);////    Function:       command////    Description:    Send a command and receive a response to/from effect engine.////    Input://          self:       handle to the effect interface this function//              is called on.//          cmdCode:    command code: the command can be a standardized command defined in//              effect_command_e (see below) or a proprietary command.//          cmdSize:    size of command in bytes//          pCmdData:   pointer to command data//          pReplyData: pointer to reply data////    Input/Output://          replySize: maximum size of reply data as input//                      actual size of reply data as output////    Output://          returned value: 0       successful operation//                          -EINVAL invalid interface handle or//                                  invalid command/reply size or format according to command code//              The return code should be restricted to indicate problems related to the this//              API specification. Status related to the execution of a particular command should be//              indicated as part of the reply field.////          *pReplyData updated with command response//int32_t (*command)(effect_handle_t self,uint32_t cmdCode,uint32_t cmdSize,void *pCmdData,uint32_t *replySize,void *pReplyData);////    Function:        get_descriptor////    Description:    Returns the effect descriptor////    Input://          self:       handle to the effect interface this function//              is called on.////    Input/Output://          pDescriptor:    address where to return the effect descriptor.////    Output://        returned value:    0          successful operation.//                          -EINVAL     invalid interface handle or invalid pDescriptor//        *pDescriptor:     updated with the effect descriptor.//int32_t (*get_descriptor)(effect_handle_t self,effect_descriptor_t *pDescriptor);////    Function:       process_reverse////    Description:    Process reverse stream function. This function is used to pass//          a reference stream to the effect engine. If the engine does not need a reference//          stream, this function pointer can be set to NULL.//          This function would typically implemented by an Echo Canceler.////    Input://          self:       handle to the effect interface this function//              is called on.//          inBuffer:   buffer descriptor indicating where to read samples to process.//              If NULL, use the configuration passed by EFFECT_CMD_SET_CONFIG_REVERSE command.////          outBuffer:   buffer descriptor indicating where to write processed samples.//              If NULL, use the configuration passed by EFFECT_CMD_SET_CONFIG_REVERSE command.//              If the buffer and buffer provider in the configuration received by//              EFFECT_CMD_SET_CONFIG_REVERSE are also NULL, do not return modified reverse//              stream data////    Output://        returned value:    0 successful operation//                          -ENODATA the engine has finished the disable phase and the framework//                                  can stop calling process_reverse()//                          -EINVAL invalid interface handle or//                                  invalid input/output buffer descriptionint32_t (*process_reverse)(effect_handle_t self,audio_buffer_t *inBuffer,audio_buffer_t *outBuffer);};

3、定制方法

库导出符号：

__attribute__ ((visibility("default")))
audio_effect_library_t AUDIO_EFFECT_LIBRARY_INFO_SYM = {tag : AUDIO_EFFECT_LIBRARY_TAG,version : EFFECT_LIBRARY_API_VERSION,name : "Downmix Library",implementor : "The Android Open Source Project",create_effect : DownmixLib_Create,release_effect : DownmixLib_Release,get_descriptor : DownmixLib_GetDescriptor,
};

库的接口：

const struct effect_interface_s gDownmixInterface = {Downmix_Process,Downmix_Command,Downmix_GetDescriptor,NULL /* no process_reverse function, no reference stream needed */
};

库的内部参数：

typedef struct XXX_module_s {const structeffect_interface_s *itfe;XXconfig;
} XXX_module_t;

gDownmixInterface的用途，在create_effect中创建XXX_module_t，并设置

module->itfe = &gDownmixInterface;

注意：必须把conststruct effect_interface_s *itfe;作为结构体的第一个元素！

安卓音效AudioEffect源码剖析2——音效库接口相关推荐

ZStack源码剖析之核心库鉴赏——FlowChain
本文首发于泊浮目的专栏:https://segmentfault.com/blog... 前言在ZStack(或者说产品化的IaaS软件)中的任务通常有很长的执行路径,错误可能发生在路径的任意一处. ...
AudioEffect源码解析
音效AudioEffect 如下图,应用程序开发者使用android.media.audiofx.AudioEffect来控制音效,它的子类包括:BassBoost, Environmental ...
老李推荐：第5章5节《MonkeyRunner源码剖析》Monkey原理分析-启动运行: 获取系统服务引用 1...
老李推荐:第5章5节<MonkeyRunner源码剖析>Monkey原理分析-启动运行: 获取系统服务引用上一节我们描述了monkey的命令处理入口函数run是如何调用optionPro ...
老李推荐：第8章4节《MonkeyRunner源码剖析》MonkeyRunner启动运行过程-启动AndroidDebugBridge 1...
老李推荐: 第8章4节<MonkeyRunner源码剖析>MonkeyRunner启动运行过程-启动AndroidDebugBridge 上一节我们看到在启动AndroidDebugBri ...
老李推荐：第3章2节《MonkeyRunner源码剖析》脚本编写示例: MonkeyDevice API使用示例 1...
老李推荐: 第3章2节<MonkeyRunner源码剖析>脚本编写示例: MonkeyDevice API使用示例上一节我们学习了如何通过MonkeyRunner这个类的静态方法wait ...
老李推荐：第14章4节《MonkeyRunner源码剖析》 HierarchyViewer实现原理-装备ViewServer-端口转发 1...
老李推荐:第14章4节<MonkeyRunner源码剖析> HierarchyViewer实现原理-装备ViewServer-端口转发在初始化HierarchyViewer的实例过程中, ...
JS魔法堂：mmDeferred源码剖析
一.前言 avalon.js的影响力愈发强劲,而作为子模块之一的mmDeferred必然成为异步调用模式学习之旅的又一站呢!本文将记录我对mmDeferred的认识,若有纰漏请各位指正,谢谢.项目请见 ...
Kafka源码剖析 —— 网络I/O篇 —— 浅析KafkaSelector
为什么80%的码农都做不了架构师?>>> ##NioSelector和KafkaSelector有什么区别? 先说结论,KafkaSelector(org.apache.kaf ...
Mongoose源码剖析：Introduction and Installation
引言要剖析Mongoose的源码,首先你得知道它的一些基本情况和特性.并去使用它.本文就是介绍Mongoose是个什么东西?及如何安装和使用?这里假设你知道什么web服务器软件.web服务器使用什么 ...
老李推荐：第3章3节《MonkeyRunner源码剖析》脚本编写示例: MonkeyImage API使用示例 1...
老李推荐:第3章3节<MonkeyRunner源码剖析>脚本编写示例: MonkeyImage API使用示例在上一节的第一个"增加日记"的示例中,我们并没有看到日记 ...

安卓音效AudioEffect源码剖析2——音效库接口

1、库的导出符号表——audio_effect_library_t

2、接口定义——effect_handle_t

3、定制方法

安卓音效AudioEffect源码剖析2——音效库接口相关推荐

最新文章

热门文章