jan老师的OpenMAX state切换示范程序

jan_OpenMAX_state_switch.c

/*
https://jan.newmarch.name/RPi/OpenMAX/State/wontwork.c
*/

/*
 * WARNING: THIS PROGRAM DOESN'T WORK  这个程序不可以直接运行
 */

#include <stdio.h>
#include <stdlib.h>

#include <OMX_Core.h>
#include <OMX_Component.h>

#include <bcm_host.h>  这个代码是给博通的树莓派的

char *err2str(int err) {
    switch (err) {
    case OMX_ErrorInsufficientResources: return "OMX_ErrorInsufficientResources";
    case OMX_ErrorUndefined: return "OMX_ErrorUndefined";
    case OMX_ErrorInvalidComponentName: return "OMX_ErrorInvalidComponentName";
    case OMX_ErrorComponentNotFound: return "OMX_ErrorComponentNotFound";
    case OMX_ErrorInvalidComponent: return "OMX_ErrorInvalidComponent";
    case OMX_ErrorBadParameter: return "OMX_ErrorBadParameter";
    case OMX_ErrorNotImplemented: return "OMX_ErrorNotImplemented";
    case OMX_ErrorUnderflow: return "OMX_ErrorUnderflow";
    case OMX_ErrorOverflow: return "OMX_ErrorOverflow";
    case OMX_ErrorHardware: return "OMX_ErrorHardware";
    case OMX_ErrorInvalidState: return "OMX_ErrorInvalidState";
    case OMX_ErrorStreamCorrupt: return "OMX_ErrorStreamCorrupt";
    case OMX_ErrorPortsNotCompatible: return "OMX_ErrorPortsNotCompatible";
    case OMX_ErrorResourcesLost: return "OMX_ErrorResourcesLost";
    case OMX_ErrorNoMore: return "OMX_ErrorNoMore";
    case OMX_ErrorVersionMismatch: return "OMX_ErrorVersionMismatch";
    case OMX_ErrorNotReady: return "OMX_ErrorNotReady";
    case OMX_ErrorTimeout: return "OMX_ErrorTimeout";
    case OMX_ErrorSameState: return "OMX_ErrorSameState";
    case OMX_ErrorResourcesPreempted: return "OMX_ErrorResourcesPreempted";
    case OMX_ErrorPortUnresponsiveDuringAllocation: return "OMX_ErrorPortUnresponsiveDuringAllocation";
    case OMX_ErrorPortUnresponsiveDuringDeallocation: return "OMX_ErrorPortUnresponsiveDuringDeallocation";
    case OMX_ErrorPortUnresponsiveDuringStop: return "OMX_ErrorPortUnresponsiveDuringStop";
    case OMX_ErrorIncorrectStateTransition: return "OMX_ErrorIncorrectStateTransition";
    case OMX_ErrorIncorrectStateOperation: return "OMX_ErrorIncorrectStateOperation";
    case OMX_ErrorUnsupportedSetting: return "OMX_ErrorUnsupportedSetting";
    case OMX_ErrorUnsupportedIndex: return "OMX_ErrorUnsupportedIndex";
    case OMX_ErrorBadPortIndex: return "OMX_ErrorBadPortIndex";
    case OMX_ErrorPortUnpopulated: return "OMX_ErrorPortUnpopulated";
    case OMX_ErrorComponentSuspended: return "OMX_ErrorComponentSuspended";
    case OMX_ErrorDynamicResourcesUnavailable: return "OMX_ErrorDynamicResourcesUnavailable";
    case OMX_ErrorMbErrorsInFrame: return "OMX_ErrorMbErrorsInFrame";
    case OMX_ErrorFormatNotDetected: return "OMX_ErrorFormatNotDetected";
    case OMX_ErrorContentPipeOpenFailed: return "OMX_ErrorContentPipeOpenFailed";
    case OMX_ErrorContentPipeCreationFailed: return "OMX_ErrorContentPipeCreationFailed";
    case OMX_ErrorSeperateTablesUsed: return "OMX_ErrorSeperateTablesUsed";
    case OMX_ErrorTunnelingUnsupported: return "OMX_ErrorTunnelingUnsupported";
    default: return "unknown error";
    }
}

void printState(OMX_HANDLETYPE handle) {
    OMX_STATETYPE state;
    OMX_ERRORTYPE err;

    err = OMX_GetState(handle, &state);  获取当前状态
    if (err != OMX_ErrorNone) {
        fprintf(stderr, "Error on getting state\n");
        exit(1);
    }
    switch (state) {
    case OMX_StateLoaded: printf("StateLoaded\n"); break;  加载了
    case OMX_StateIdle: printf("StateIdle\n"); break;  空闲
    case OMX_StateExecuting: printf("StateExecuting\n"); break; 执行中
    case OMX_StatePause: printf("StatePause\n"); break;  暂停
    case OMX_StateWaitForResources: printf("StateWait\n"); break;  等待
    case OMX_StateInvalid: printf("StateInvalid\n"); break;  不合理的状态
    default:  printf("State unknown\n"); break;  未知的状态
    }
}

这是一个回调函数
OMX_ERRORTYPE cEventHandler(
                            OMX_HANDLETYPE hComponent,
                            OMX_PTR pAppData,
                            OMX_EVENTTYPE eEvent,
                            OMX_U32 Data1,
                            OMX_U32 Data2,
                            OMX_PTR pEventData) {

    printf("Hi there, I am in the %s callback\n", __func__);
    printf("Event is %i\n", (int)eEvent);
    printf("Param1 is %i\n", (int)Data1);
    printf("Param2 is %i\n", (int)Data2);

    return OMX_ErrorNone;
}

回调
OMX_CALLBACKTYPE callbacks  = { .EventHandler = cEventHandler,
                                .EmptyBufferDone = NULL,
                                .FillBufferDone = NULL
};


int main(int argc, char** argv) {

    int i;
    char *componentName;
    OMX_ERRORTYPE err;
    OMX_HANDLETYPE handle;

    if (argc < 2) {
	fprintf(stderr, "Usage: %s component-name\n", argv[0]);
	exit(1);
    }
    componentName = argv[1];  组件名字

    bcm_host_init();

    err = OMX_Init();
    if(err != OMX_ErrorNone) {
	fprintf(stderr, "OMX_Init() failed %s\n", err2str(err));
	exit(1);
    }
    /** Ask the core for a handle to the component
     */
    err = OMX_GetHandle(&handle, componentName,   组件的句柄，传递了回调进来
                        // the next two fields are discussed later 
                        NULL, &callbacks);    
    if (err != OMX_ErrorNone) {
	fprintf(stderr, "OMX_GetHandle failed %s\n", err2str(err));
	exit(1);
    }

    // check our current state - should be Loaded
    printState(handle);

    // request a move to idle          切换状态到idle
    OMX_SendCommand(handle,
		    OMX_CommandStateSet, 
		    OMX_StateIdle,
		    NULL);

    int n = 0;
    while (n++ < 10) {
	sleep(1);
	// are we there yet?
	printState(handle);         这个时候应该切换成功了吧
    }
 
    exit(0);
}