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• FFmpeg.AutoGen decoding an image using av_image_copy_to_buffer

  28 juin 2022, par Steve

  I try to use FFmpeg.AutoGen.av_image_copy_to_buffer to get decoded data into my application defined frame_buffer like so :

  


  bytes_decoded = ffmpeg.av_image_copy_to_buffer(frame_data, buffer_size, frame->data, frame->linesize, 
                                               codCtx->pix_fmt, codCtx->width, codCtx->height, 1);


  


  However the type of the parameter frame->data is of type FFmpeg.AutoGen.byte_ptrArray8, but the interface expects FFmpeg.AutoGen.byte_ptrArray4.
Does anyone know how to convert this parameter, so that I can pass it to the interface ? VS complains with the following error message :
https://docs.microsoft.com/en-us/dotnet/csharp/misc/cs1503?f1url=%3FappId%3Droslyn%26k%3Dk(CS1503)

  


  Thanks in advance for any help on this issue.

  


• Play MPEG-2 TS using MseStreamSource

  27 novembre 2022, par Nicolas Séveno

  I need to display a live video stream in a UWP application.

  



  The video stream comes from a GoPro. It is transported by UDP messages. It is a MPEG-2 TS stream. I can play it successfully using FFPlay with the following command line :

  



  ffplay -fflags nobuffer -f:v mpegts udp://:8554


  



  I would like to play it with MediaPlayerElement without using a third party library.

  



  According to the following page :
https://learn.microsoft.com/en-us/windows/uwp/audio-video-camera/supported-codecs
UWP should be able to play it. (I installed the "Microsoft DVD" application in the Windows Store).

  



  I receive the MPEG-2 TS stream with a UdpClient. It works well.
I receive in each UdpReceiveResult a 12 bytes header, followed by 4, 5, 6, or 7 MPEGTS packets (each packet is 188 bytes, beginning with 0x47).

  



  I created a MseStreamSource :

  



  _mseStreamSource = new MseStreamSource();
_mseStreamSource.Opened += (_, __) =>
{
    _mseSourceBuffer = _mseStreamSource.AddSourceBuffer("video/mp2t");
    _mseSourceBuffer.Mode = MseAppendMode.Sequence;
};
_mediaPlayerElement.MediaSource = MediaSource.CreateFromMseStreamSource(_mseStreamSource);


  



  This is how I send the messages to the MseStreamSource :

  



      UdpReceiveResult receiveResult = await _udpClient.ReceiveAsync();
    byte[] bytes = receiveResult.Buffer;
    mseSourceBuffer.AppendBuffer(bytes.AsBuffer());


  



  The MediaPlayerElement displays the message "video not supported or incorrect file name". (not sure of the message, my Windows is in French).

  



  Is it a good idea to use the MseAppendMode.Sequence mode ?
What should I pass to the AppendBuffer method ? The raw udp message including the 12 bytes header or each MPEGTS 188 bytes packet ?

  


• extracting single frame from MediaElemet or FFmpegInterop

  13 janvier 2016, par Jakub Wisniewski

  I am writing app (Windows Phone 8.1 Store App) that allows user to connect to IP Camera. I am using FFmpeg Interop library for ffmpeg which allows me to play eg. rtsp streams in media element. I need now a way to somehow extract a single frame from stream or from media element.

  I have tested other application wchih allows connecting to IP cameras - IP Centcom, and they have working snapshots only for mjpeg streams as far as I now (they were not working for rtsp). Becouse of that I belive that it is impossible or at very least very hard to export frame from media element.

  I have different question - if anyone has ever used FFmpeg Interop and would like to help/explain me how could I modify/extend FFmpegInteropMSS to add method called ’GetThumbnailForStream’ that would work similary to ’GetMediaStreamSource’ but would return single frame (bitmap or jpg) instead of MediaStreamSource ?

  Every help would be appreciated

  EDIT :

  I have found something ;

  in MediaSampleProvider in method WriteAVPacketToStream (line 123) there is line

  auto aBuffer = ref new Platform::Array(avPacket->data, avPacket->size);

  and I belive that this is the place that stores single frame data that is needed to convert into bitmap - now since I do not know c++ too much I have a question : how can I convert it into a form that I could return via public method ?

  When returning :

  Platform::Array^

  I get

  ’FFmpegInterop::MediaSampleProvider’ : a non-value type cannot have any public data members

  EDIT2 :

  Ok I am doing approprate projection to byte according to this microsoft information, now I need to check if this is correct data.