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• Draw FFmpeg AVFrame data with OpenGL in Go

  27 avril 2018, par nevernew

  I’m making a video player in Go (on Windows) using FFmpeg and OpenGl, with the go wrappers goav and go-gl respectively. I want to set the pixels (stored in AVFrame->data) as a texture to display with OpenGL.

  I have it drawing pixels from a test array I created in Go, but it’s not taking the AVFrame data at all. The gl wrapper is giving me an error panic: reflect: call of reflect.Value.Pointer on uintptr Value with this code, I’ve tried different ways, trying to cast the data to the right type to be accepted but to no avail.

  This is the offending code where f is of type *Frame :

  type Frame C.struct_AVFrame
  
  
  
  dataPtr := (*uint8)(unsafe.Pointer((*C.uint8_t)(unsafe.Pointer(&f.data))))
  
  dataAddr := uintptr(unsafe.Pointer(dataPtr))
  
  
  
  glPixelPointer := gl.Ptr(dataAddr) // reflect error happens here, so the pointer is wrong

  Trying to get the data from this C struct :

  #include 
  
  
  
  typedef struct AVFrame {
  
  #define AV_NUM_DATA_POINTERS 8
  
      uint8_t *data[AV_NUM_DATA_POINTERS];
  
  }

  I can provide the rest of the code if needed, but there’s a lot of it to get the example running.

• Draw FFmpeg AVFrame data with OpenGL with Go

  27 avril 2018, par nevernew

  I’m making a video player in Go (on Windows) using FFmpeg and OpenGl, with the go wrappers goav and go-gl respectively. I want to set the pixels (stored in AVFrame->data) as a texture to display with OpenGL.

  I have it drawing pixels from a test array I created in Go, but it’s not taking the AVFrame data at all. The gl wrapper is giving me an error panic: reflect: call of reflect.Value.Pointer on uintptr Value with this code, I’ve tried different ways, trying to cast the data to the right type to be accepted but to no avail.

  This is the offending code where f is of type *Frame :

  type Frame C.struct_AVFrame
  
  
  
  dataPtr := (*uint8)(unsafe.Pointer((*C.uint8_t)(unsafe.Pointer(&f.data))))
  
  dataAddr := uintptr(unsafe.Pointer(dataPtr))
  
  
  
  glPixelPointer := gl.Ptr(dataAddr) // reflect error happens here, so the pointer is wrong

  Trying to get the data from this C struct :

  #include 
  
  
  
  typedef struct AVFrame {
  
  #define AV_NUM_DATA_POINTERS 8
  
      uint8_t *data[AV_NUM_DATA_POINTERS];
  
  }

  I can provide the rest of the code if needed, but there’s a lot of it to get the example running.

• How to make ffmpeg configure add to the end of compiling line ?

  28 octobre 2012, par myWallJSON

  I want to make ffmpeg not to use -fno-math-errno on compilation.

  I tried ./configure --extra-cflags="-fmath-errno"

  but it ads it before ffmpegs -fno-math-errno :

  gcc -I. -I./ -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -DHAVE_AV_CONFIG_H   -std=c99 -fomit-frame-pointer -I/cygdrive/c/Users/Avesta/Downloads/FlasCC_1.0.1121790_10-08-2012/sdk/usr/include/SDL -D_GNU_SOURCE=1 -Wdeclaration-after-statement -Wall -Wno-parentheses -Wno-switch -Wno-format-zero-length -Wdisabled-optimization -Wpointer-arith -Wredundant-decls -Wno-pointer-sign -Wwrite-strings -Wundef -Wmissing-prototypes -Wno-pointer-to-int-cast -Wstrict-prototypes -O3  -mllvm -stack-alignment=16  -MMD -MF libavformat/allformats.d -MT libavformat/allformats.o -c -o libavformat/allformats.o libavformat/allformats.c

  \so I wonder how to make configure to add flags after all -f including -fno-math-errno ?

  there are :

    --extra-cflags=ECFLAGS   add ECFLAGS to CFLAGS []
  
    --extra-cxxflags=ECFLAGS add ECFLAGS to CXXFLAGS []
  
    --extra-ldflags=ELDFLAGS add ELDFLAGS to LDFLAGS []
  
    --extra-libs=ELIBS       add ELIBS []
  
    --extra-version=STRING   version string suffix []