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• libav : Filling AVFrame with RGB24 sample data ?

  31 mai 2012, par Ashika Umanga Umagiliya

  I am trying to fill sample data for a AVFrame initialized with RGB24 format.
  I use following code snippet to populate RGB data.
  But in the encoded video,I can only see grayscale strip covering only 1/3 of the videoframe.
  This code snippet suppose to fill only Red color.
  Any tips what Im doing wrong here ?

  AVFrame *targetFrame=.....
  
  int height=imageHeight();
  
  int width=imageWidth();
  
  
  
  
  
    for(y=0;ydata[0][(y* width)+x]=(x%255); //R  
  
     targetFrame->data[0][(y* width)+x+1]=0;     //G
  
     targetFrame->data[0][(y* width)+x+2]=0;     //B
  
  
  
  
  
    }
  
     }

• Named pipes and can they stream data ?

  30 juillet 2013, par chembrad

  I asked a previous question here :

  Stream video from ffmpeg and capture with OpenCV

  and I want to know more about named pipes in general. Can I use named pipes to stream data ? For example, can I continuously add data to the pipe (via ffmpeg) in conjunction with reading data with another application ? Or is there another method to do this ?

• Do I need an AVFormatContext for decoding raw audio data ?

  4 décembre 2023, par CheekyChips

  I am streaming encoded audio data to my program, in raw byte arrays. The audio data could have any encoding but when I receive the data I will know the encoding, sample rate, etc, so I know how to interpret it. Using ffmpeg/libav libraries, I want to decode the audio chunks when I receive them and do some processing with them (e.g. resampling). My question is, since I am getting raw encoded audio data that is not wrapped in a file format, do I still need to create a AVFormatContext and use av_read_frame() to get the encoded AVPacket ? Or should I just create an AVPacket using av_packet_from_data(AVPacket *pkt, uint8_t *data, int size) and manually set the properties like encoding, sample rate, etc ? It is my understanding that AVFormatContext is meant for representing file formats, i.e. wrappers, so I don't know if it would work if I use raw encoded audio data (which I would access through a custom AVIOContext). Also, since I want to support lots of different audio codecs as input, I don't know if the different frame sizes for different codecs will make it difficult to create an AVPacket, if I have the wrong number of samples in my data array, so maybe an AVFormatContext would be better.

  


  Which is the better approach for decoding raw encoded audio chunks - creating an AVFormatContext or AVPackets ?