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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.

• Ffmpeg stream problems with buffer data

  27 juin 2023, par Erdem Ün

  my code is not working. I cannot conversion. how can I fix ?

  


  readable event working but Error output is

  


  


  data undefined

  


  


  try {

    const readStream = fs.createReadStream('./ses.webm');

    const command = childProcess.spawn('ffmpeg', ['-i', 'pipe:0', '-c:a', 'aac', 'pipe:1']);

    readStream.pipe(command.stdin);
    command.stdout.on('readable', (a) => {
      console.log('data', a)
    });

    command.on('data', (code) => {
      console.log(`ffmpeg işlemi tamamlandı. Çıkış kodu: ${code}`);
    });
  } catch (error) {
    console.log(error)
  }


  


• Need a better understanding of HTML 5 audio/video meta data use and placement

  24 juin 2012, par nicoz

  I have spent a significant amount of time researching HTML 5 audio and video, however I am stuck understandong the encoding of the meta data. It seems that in my research, using programs like Handbrake (ffmpeg) it is recommend to check of "web optimized" (also using this type of setting when say exporting from imovie). I have concluded that this has to do with moving the file's meta data to the beginning of the file. This then gives the player/browser the info it requires to play immediately without having to wait to load the entire file.

  So here is where I am confused and the questions

  Does this only apply to mp4 files ? (I need to also encode/transcode .ogv and .webm)
  Where does the mp4 MOOV atom fit into this or is that what people are referring to, when they say move the meta data to the front of the file ?