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• why cmd just print command and dosen't work ?

  11 octobre 2019, par 杨士弘

  I tried create a website that could upload mp4 then my server would transcode it to ts and create a m3u8 playlist。
  I wanted to use cmd to control ffmpeg to do this，and I use visual basic to do this.

  Here is my code：

    Dim fileName As String = "borderoflife"
  
    Dim file As String = "borderoflife.mp4"
  
    Dim appPath As String = "C:\allen0916\"
  
    Dim saveDir As String = "test2\"
  
  
  
    Dim savePath As String = appPath & saveDir
  
    Dim saveResult As String = savePath & file
  
  
  
    Dim Content_Type_A As String = "video/mp4"
  
  
  
    Dim m3u8Path As String = Path.Combine(savePath, fileName + ".m3u8")
  
    Dim para As String = String.Format("/C ffmpeg -i {0} -profile:v baseline -level 3.0 -s 640x360 -start_number 0 -hls_time 10 -hls_list_size 0 -f hls {1} ", saveResult, m3u8Path)
  
  
  
    Dim output As String = "none" 
  
    Dim p As Process = New Process()
  
  
  
    p.StartInfo.FileName = "cmd.exe"
  
    p.StartInfo.UseShellExecute = False 
  
    p.StartInfo.RedirectStandardInput = True 
  
    p.StartInfo.RedirectStandardOutput = True 
  
    p.StartInfo.RedirectStandardError = True 
  
    p.StartInfo.CreateNoWindow = True 
  
    p.Start()
  
    p.StandardInput.WriteLine(para) 
  
    p.StandardInput.WriteLine("exit")
  
    p.StandardInput.AutoFlush = True
  
    p.StandardInput.Close() 
  
    output = p.StandardOutput.ReadToEnd() 
  
    p.WaitForExit()
  
    p.Close()
  
  
  
   If System.IO.File.Exists(m3u8Path) <> True Then
  
        context.Response.Write(output)
  
    Else
  
        context.Response.Write("Success")
  
    End If  

  and every time output just returns ：

  Microsoft Windows [version 10.0.17763.737]
  
  (c) 2018 Microsoft Corporation. 
  
  
  
  c:\windows\system32\inetsrv>/C ffmpeg -i C:\allen0916\test2\borderoflife.mp4 -profile:v baseline -level 3.0 -s 640x360 -start_number 0 -hls_time 10 -hls_list_size 0 -f hls C:\allen0916\test2\borderoflife.m3u8 
  
  
  
  c:\windows\system32\inetsrv>exit

  it seems cmd.exe just print my command and not working，
  Dose somebody know why？

• images->video->web canvas : RGB/YUV issues

  5 février 2016, par nrob

  We’ve written an web app which :

  1. takes 3D, time dependent weather data
  2. tiles each 3D time point to make a 2D frame (written out as a png image)
  3. stitches these frames together into a video (using ffmpeg/avconv)
  4. streams this video into a web app
  5. polls the canvas for frames
  6. sends the frames to the GPU where they are converted back to 3D and ray traced

  You can see the app here, code here and you can see the data video here

  Currently the pngs are written as RGB images, the video codec is in YUV and getting frames from the canvas returns RGB. As such there is a significant loss of information due to the conversion between image spaces.

  Does anyone have suggestions what is the best way round this ?

  I’ve tried a bunch of RGB video codecs, but I can’t get any to work, and I don’t know if the web browser will support it anyway. Can anyone suggest a good RGB codec (both lossy and lossless would be great)

  Also, is it possible to write to YUV images/read them from a video canvas in HTML5 ?

  Ultimately, I don’t even want anything to do with images/videos, I’m just hacking the codecs to stream/compress large animated 3D data volumes

• FFmpeg : Encode x264 with AMD GPU on Windows ?

  20 septembre 2023, par ZeroTek

  I am currently trying to record a Video on my Lenovo Laptop with its Built-In Webcam using FFmpeg on Windows 10. One of my goals is to keep the CPU Usage as low as possible, that's why i want to push the h264 encoding to the GPU. 
Now it gets a bit tricky here with my Laptop. Because it uses two GPUs. The first GPU is a Intel HD 5500 Graphics Unit as Part of the CPU. This one is most likly used for non-demanding Applications like office etc. to save Energy. The other one is a AMD R5 M330 that will be used for graphic intense applications like gaming.

  



  Currently, i am using the following command to encode the Webcam Stream on the Intel HD GPU :

  



  ffmpeg -f dshow -vcodec mjpeg -video_size 1280x720 -framerate 30 video="Lenovo EasyCamera":audio="Mikrofon (Realtek High Definition Audio)" -c:v h264_qsv -g 60 -q 28 -look_ahead 0 -preset:v faster -c:a aac -q:a 0.6 -r 30 output.mp4


  



  This does work so far but it seems this GPU does not have enough Power to keep up with the framerate on higher bitrates or with a high amount of i-frames. The Video starts lacking and skipping frames. If i am using CPU encoding everything works smooth.

  



  Now that my Laptop got that second AMD GPU with a lot more Power it would be a nice Try to encode on that one, but i can't find any information about how to encode on AMD Hardware on Windows 10. So my question is : How does the ffmpeg command look like to use AMD Hardware for h264 encoding ?