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• How to convert a Stream on the fly with FFMpegCore ?

  18 octobre 2023, par Adrian

  For a school project, I need to stream videos that I get from torrents while they are downloading on the server.
When the video is a .mp4 file, there's no problem, but I must also be able to stream .mkv files, and for that I need to convert them into .mp4 before sending them to the client, and I can't find a way to convert my Stream that I get from MonoTorrents with FFMpegCore into a Stream that I can send to my client.

  


  Here is the code I wrote to simply download and stream my torrent :

  


  var cEngine = new ClientEngine();

var manager = await cEngine.AddStreamingAsync(GenerateMagnet(torrent), ) ?? throw new Exception("An error occurred while creating the torrent manager");

await manager.StartAsync();
await manager.WaitForMetadataAsync();

var videoFile = manager.Files.OrderByDescending(f => f.Length).FirstOrDefault();
if (videoFile == null)
    return Results.NotFound();

var stream = await manager.StreamProvider!.CreateStreamAsync(videoFile, true);
return Results.File(stream, contentType: "video/mp4", fileDownloadName: manager.Name, enableRangeProcessing: true);


  


  I saw that the most common way to convert videos is by using ffmpeg. .NET has a package called FFMpefCore that is a wrapper for ffmpeg.

  


  To my previous code, I would add right before the return :

  


  if (!videoFile.Path.EndsWith(".mp4"))
{
    var outputStream = new MemoryStream();
    FFMpegArguments
        .FromPipeInput(new StreamPipeSource(stream), options =>
        {
            options.ForceFormat("mp4");
        })
        .OutputToPipe(new StreamPipeSink(outputStream))
        .ProcessAsynchronously();
    return Results.File(outputStream, contentType: "video/mp4", fileDownloadName: manager.Name, enableRangeProcessing: true);
}


  


  I unfortunately can't get a "live" Stream to send to my client.

  


• Evolution #3928 : les emails sont publics dans le privé

  6 mai 2017, par guytarr °

  nico d_ a écrit :

  J’aurais dû préciser que je parlais de masquer les emails des auteurs pour les rédacteurs uniquement.
  C’est à dire le cas de figure soulevé par la citation de départ : je m’inscris sur un site et je vois les emails de tout le monde.

  Ca va dépendre des sites et des usages / sites :
  - parfois, on voudra que les inscrits choississent s’ils partagent leur email ou pas lorsqu’ils s’inscrivent
  - parfois, on aura besoin de le forcer
  - parfois on voudra le masquer
  - etc...

  Je le lie à l’autre sujet sur la modération des inscriptions car c’est un petit chantier à appréhender de façon global

• Array Getting Lost While Passing From C++ to C Using Callback [duplicate]

  23 décembre 2020, par Abhishek Sharma

  I am trying to write Video Using FFmpeg by generating frame at run time using direct3d and the frames are generated using sharp dx at c# and I use window runtime to callback to c# to generate Frame And return Platform::Array of Byte ;

  


  so for writing video using FFmpeg, I used C code that writes video, and to ask for generating frame I implemented a callback to generate a frame and all that in StaticLib

  


  uint8_t*(*genrate_frame_callback)(int) = NULL;   


  


  now in C-File, I call fill_image to get the frame and write to the video

  


  static void fill_image(int frame_index, int width, int height)
{
    int x, y, i;

    i = frame_index;
    auto result = genrate_frame_callback(frame_index);// after passing this point while using debugger reults single element not even array
    .
    .
    .
    code to write video
    
}


  


  now when I call to Write Video before that pass this function to the callback that is in the c++ file in a Window Runtime Component that reference to static lib

  


  uint8_t* genrate_frame(int args)&#xA;{&#xA;    auto frame = FireGenrateFramet(args); // returns Platform::Array<byte>&#xA;    vector v(frame->begin(), frame->end());&#xA;    return v.data();// data is abilabe to this point &#xA;}&#xA;</byte>

  


  now the result variable contains a single element
I am new to c++ and c and unable to understand why is data not passed to the function using call back

  


  Edit :

  


  then can you help me with how to pass Data I tried using the global Scope Variable c++ file too but still,
it gets lost,
but after introducing another call back to read data stored in global Variable it read the whole data correctly

  


  vector frame_v;
uint8_t* genrate_frame(int args)
{
    auto frame = FireGenrateFrame(args);
     vector v(frame->begin(), frame->end());
    frame_v = v;
    return v.data();// this loose the Same 
}

uint8_t read_pixal(int args)
{
    return frame_v[args];// where as it read out correctly
}


  


  but I don't want to store and add new call back an read from their just pass the array