Recherche avancée

Sur d’autres sites (5914)

• swscale/aarch64 : add hscale specializations

  26 mai 2022, par Swinney, Jonathan

  swscale/aarch64 : add hscale specializations
  This patch adds code to support specializations of the hscale function
  
  and adds a specialization for filterSize == 4.
  ff_hscale8to15_4_neon is a complete rewrite. Since the main bottleneck
  
  here is loading the data from src, this data is loaded a whole block
  
  ahead and stored back to the stack to be loaded again with ld4. This
  
  arranges the data for most efficient use of the vector instructions and
  
  removes the need for completion adds at the end. The number of
  
  iterations of the C per iteration of the assembly is increased from 4 to
  
  8, but because of the prefetching, there must be a special section
  
  without prefetching when dstW < 16.
  This improves speed on Graviton 2 (Neoverse N1) dramatically in the case
  
  where previously fs=8 would have been required.
  before : hscale_8_to_15__fs_8_dstW_512_neon : 1962.8
  
  after : hscale_8_to_15__fs_4_dstW_512_neon : 1220.9
  Signed-off-by : Jonathan Swinney <jswinney@amazon.com>
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libswscale/aarch64/hscale.S
  • [DH] libswscale/aarch64/swscale.c
  • [DH] libswscale/utils.c

• Find video resolution and video duration of remote mediafile

  22 février 2012, par osgx

  I want to write an program which can find some metainformation of mediafile. I'm interested in popular video formats, such as avi, mkv, mp4, mov (may be other popular too). I want basically to get :

  • Video size (720, 1080, 360 etc)
  • Total runtime of video (may be not very exact)
  • Number of audio streams
  • Name of video codec
  • Name of audio codec

  There is already the mediainfo, but in my program I want to get information about remote file, which may be accessed via ftp, http, samba ; or even torrent (there are some torrent solutions, which allows to read not-yet downloaded file).

  MediaInfo library have no support of samba (smb ://) and mkv format (for runtime).

  Also, I want to know, how much data should be downloaded to get this information. I want not to download full videofile because I have no enough disk space.

  Is this information in the first 1 or 10 or 100 KiloBytes of the file ? Is it at predictable offset if I know the container name and total file size ?

  PS : Platform is Linux, Language is C/C++

• 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.