ffmpeg讀取攝像頭并且推流 · 音視頻/C++/k8s/Docker等等學習筆記

[TOC] 雷神傳送門：[https://blog.csdn.net/leixiaohua1020/article/details/39702113](https://blog.csdn.net/leixiaohua1020/article/details/39702113) ## 概述 FFmpeg中有一個和多媒體設備交互的類庫：Libavdevice。使用這個庫可以讀取電腦（或者其他設備上）的多媒體設備的數據，或者輸出數據到指定的多媒體設備上。 ## libavdevice使用使用libavdevice的時候需要包含其頭文件： ``` #include "libavdevice/avdevice.h" ``` 然后，在程序中需要注冊libavdevice： ``` avdevice_register_all(); ``` 接下來就可以使用libavdevice的功能了。使用libavdevice讀取數據和直接打開視頻文件比較類似。因為系統的設備也被FFmpeg認為是一種輸入的格式（即AVInputFormat）。使用FFmpeg打開一個普通的視頻文件使用如下函數： ``` AVFormatContext *pFormatCtx = avformat_alloc_context(); avformat_open_input(&pFormatCtx, "test.h265",NULL,NULL); ``` 使用libavdevice的時候，唯一的不同在于需要首先查找用于輸入的設備。在這里使用av_find_input_format()完成： ``` AVFormatContext *pFormatCtx = avformat_alloc_context(); AVInputFormat *ifmt=av_find_input_format("vfwcap"); avformat_open_input(&pFormatCtx, 0, ifmt,NULL); ``` 上述代碼首先指定了vfw設備作為輸入設備，然后在URL中指定打開第0個設備（在我自己計算機上即是攝像頭設備）。在Windows平臺上除了使用vfw設備作為輸入設備之外，還可以使用DirectShow作為輸入設備： ``` AVFormatContext *pFormatCtx = avformat_alloc_context(); AVInputFormat *ifmt=av_find_input_format("dshow"); avformat_open_input(&pFormatCtx,"video=Integrated Camera",ifmt,NULL) ; ``` ## 調用攝像頭 [https://blog.csdn.net/weixin\_39743893/article/details/80714217](https://blog.csdn.net/weixin_39743893/article/details/80714217) 遇到的問題，就是直接使用引用庫就行。在mac上不要使用vcpkg生成的變量${FFMPEG_LIBRARIES} 會造成qt調用obcj的問題。 ``` Undefined symbols for architecture x86\_64: "\_AVMediaTypeAudio", referenced from: \_avf\_read\_header in libavdevice.a(avfoundation.o) "\_AVMediaTypeMuxed", referenced from: \_avf\_read\_header in libavdevice.a(avfoundation.o) "\_AVMediaTypeVideo", referenced from: \_avf\_read\_header in libavdevice.a(avfoundation.o) "\_CGBitmapContextCreate", referenced from: \_apply\_filter in libavfilter.a(vf\_coreimage.o) "\_CGColorSpaceCreateWithName", referenced from: \_init in libavfilter.a(vf\_coreimage.o) "\_CGContextDrawImage", referenced from: \_apply\_filter in libavfilter.a(vf\_coreimage.o) "\_CGContextRelease", referenced from: \_apply\_filter in libavfilter.a(vf\_coreimage.o) "\_CGGetActiveDisplayList", referenced from: \_avf\_read\_header in libavdevice.a(avfoundation.o) "\_CGImageGetHeight", referenced from: \_apply\_filter in libavfilter.a(vf\_coreimage.o) "\_CGImageGetWidth", referenced from: \_apply\_filter in libavfilter.a(vf\_coreimage.o) "\_CGLGetCurrentContext", referenced from: \_init in libavfilter.a(vf\_coreimage.o) "\_NSRectFromString", referenced from: \_apply\_filter in libavfilter.a(vf\_coreimage.o) "\_NSUndefinedKeyException", referenced from: \_avf\_read\_header in libavdevice.a(avfoundation.o) \_apply\_filter in libavfilter.a(vf\_coreimage.o) "\_OBJC\_CLASS\_$\_AVCaptureAudioDataOutput", referenced from: objc-class-ref in libavdevice.a(avfoundation.o) "\_OBJC\_CLASS\_$\_AVCaptureDevice", referenced from: objc-class-ref in libavdevice.a(avfoundation.o) "\_OBJC\_CLASS\_$\_AVCaptureDeviceInput", referenced from: objc-class-ref in libavdevice.a(avfoundation.o) "\_OBJC\_CLASS\_$\_AVCaptureScreenInput", referenced from: objc-class-ref in libavdevice.a(avfoundation.o) "\_OBJC\_CLASS\_$\_AVCaptureSession", referenced from: objc-class-ref in libavdevice.a(avfoundation.o) "\_OBJC\_CLASS\_$\_AVCaptureVideoDataOutput", referenced from: objc-class-ref in libavdevice.a(avfoundation.o) "\_OBJC\_CLASS\_$\_CIColor", referenced from: objc-class-ref in libavfilter.a(vf\_coreimage.o) "\_OBJC\_CLASS\_$\_CIContext", referenced from: objc-class-ref in libavfilter.a(vf\_coreimage.o) "\_OBJC\_CLASS\_$\_CIFilter", referenced from: objc-class-ref in libavfilter.a(vf\_coreimage.o) "\_OBJC\_CLASS\_$\_CIImage", referenced from: objc-class-ref in libavfilter.a(vf\_coreimage.o) "\_OBJC\_CLASS\_$\_CIVector", referenced from: objc-class-ref in libavfilter.a(vf\_coreimage.o) "\_OBJC\_CLASS\_$\_NSAutoreleasePool", referenced from: objc-class-ref in libavdevice.a(avfoundation.o) "\_OBJC\_CLASS\_$\_NSNumber", referenced from: objc-class-ref in libavdevice.a(avfoundation.o) objc-class-ref in libavfilter.a(vf\_coreimage.o) "\_OBJC\_CLASS\_$\_NSOpenGLPixelFormat", referenced from: objc-class-ref in libavfilter.a(vf\_coreimage.o) "\_OBJC\_CLASS\_$\_NSString", referenced from: objc-class-ref in libavfilter.a(vf\_coreimage.o) "\_SDL\_CreateTexture", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) "\_SDL\_CreateWindowAndRenderer", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) "\_SDL\_DestroyRenderer", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) \_sdl2\_write\_packet in libavdevice.a(sdl2.o) \_sdl2\_write\_trailer in libavdevice.a(sdl2.o) "\_SDL\_DestroyTexture", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) \_sdl2\_write\_packet in libavdevice.a(sdl2.o) \_sdl2\_write\_trailer in libavdevice.a(sdl2.o) "\_SDL\_DestroyWindow", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) \_sdl2\_write\_packet in libavdevice.a(sdl2.o) \_sdl2\_write\_trailer in libavdevice.a(sdl2.o) "\_SDL\_GetError", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) "\_SDL\_Init", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) "\_SDL\_PollEvent", referenced from: \_sdl2\_write\_packet in libavdevice.a(sdl2.o) "\_SDL\_Quit", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) \_sdl2\_write\_packet in libavdevice.a(sdl2.o) \_sdl2\_write\_trailer in libavdevice.a(sdl2.o) "\_SDL\_RenderClear", referenced from: \_sdl2\_write\_packet in libavdevice.a(sdl2.o) "\_SDL\_RenderCopy", referenced from: \_sdl2\_write\_packet in libavdevice.a(sdl2.o) "\_SDL\_RenderPresent", referenced from: \_sdl2\_write\_packet in libavdevice.a(sdl2.o) "\_SDL\_SetWindowPosition", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) "\_SDL\_SetWindowTitle", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) "\_SDL\_ShowWindow", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) "\_SDL\_UpdateTexture", referenced from: \_sdl2\_write\_packet in libavdevice.a(sdl2.o) "\_SDL\_UpdateYUVTexture", referenced from: \_sdl2\_write\_packet in libavdevice.a(sdl2.o) "\_SDL\_WasInit", referenced from: \_sdl2\_write\_header in libavdevice.a(sdl2.o) "\_kCGColorSpaceGenericRGB", referenced from: \_init in libavfilter.a(vf\_coreimage.o) "\_kCIAttributeClass", referenced from: \_init in libavfilter.a(vf\_coreimage.o) "\_kCIAttributeDefault", referenced from: \_init in libavfilter.a(vf\_coreimage.o) "\_kCIAttributeSliderMax", referenced from: \_init in libavfilter.a(vf\_coreimage.o) "\_kCIAttributeSliderMin", referenced from: \_init in libavfilter.a(vf\_coreimage.o) "\_kCIAttributeType", referenced from: \_init in libavfilter.a(vf\_coreimage.o) "\_kCICategoryGenerator", referenced from: \_init in libavfilter.a(vf\_coreimage.o) "\_kCIFormatARGB8", referenced from: \_apply\_filter in libavfilter.a(vf\_coreimage.o) "\_kCIInputImageKey", referenced from: \_apply\_filter in libavfilter.a(vf\_coreimage.o) "\_kCIOutputImageKey", referenced from: \_apply\_filter in libavfilter.a(vf\_coreimage.o) ld: symbol(s) not found for architecture x86\_64 ``` ## Video codec rawvideo not compatible with flv 在mac上捕獲不到攝像頭，捕獲屏幕，然后推流出現的錯誤。原因文件使用的視頻格式是 rawvideo，這個太新了，由于flv 已經不更新了，所以不能在 flv文件中寫入 rawvideo格式的視頻。你轉成? flv文件之所以可以推流是因為在轉格式的時候視頻格式也發生了變化，就成了flv可以支持的視頻格式，所以才能推流成功。