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• Google Colab Runtime Error please install ffmpeg (version 4.2 is currently supported) andbuild torchvision from source

  4 juillet 2021, par Iman

  I'm using Google Colab to write a program using torch vision to extract frames from an mp4 video in my google drive. Thus far, I haven't wrote the full code yet but have been experimenting with torch vision.io library. Upon running the code, I get the following errors.

  


  Mounted at /content/gdrive&#xA;---------------------------------------------------------------------------&#xA;RuntimeError                              Traceback (most recent call last)&#xA; in <module>()&#xA;      6 &#xA;      7 video_path = "/content/drive/MyDrive/Training-Data-Videos/MASKED/00_MASKED_0_0.mp4"&#xA;----> 8 reader = torchvision.io.VideoReader(video_path, "video")&#xA;      9 reader.seek(2.0)&#xA;     10 frame = next(reader)&#xA;&#xA;/usr/local/lib/python3.7/dist-packages/torchvision/io/__init__.py in __init__(self, path, stream)&#xA;    106                 &#x2B; "to enable video_reader support, please install "&#xA;    107                 &#x2B; "ffmpeg (version 4.2 is currently supported) and"&#xA;--> 108                 &#x2B; "build torchvision from source."&#xA;    109             )&#xA;    110         self._c = torch.classes.torchvision.Video(path, stream)&#xA;&#xA;RuntimeError: Not compiled with video_reader support, to enable video_reader support, please install ffmpeg (version 4.2 is currently supported) andbuild torchvision from source.&#xA;&#xA;</module>

  


  The code that I have written in the notebook so far is the following :

  


  import os 
import torchvision 
from google.colab import drive
drive.mount('/content/gdrive', force_remount=True)

video_path = "/content/drive/MyDrive/Training-Data-Videos/MASKED/00_MASKED_0_0.mp4"
reader = torchvision.io.VideoReader(video_path, "video")
reader.seek(2.0)
frame = next(reader)
print (frame)



  


  To solve the problem, I tried to install ffmpeg on colab as this post says but it did not work. Can someone tell me what is the error ?

  


• I can't get bitmap from Process StandardOutput pipe ffmpeg

  7 juin 2018, par Srdjan M.

  Following article Read and Write Video Frames Using FFMPEG, I am trying to extract and process all frames from a video. The problem is that I don’t get exact same bytes in buffer and sample image.

  string Arguments = string.Format(@"-i {0} -f image2pipe -pix_fmt bgr24 -vcodec rawvideo pipe:", "output.mp4");
  
  using (Process process = new Process())
  
  {
  
      process.StartInfo.CreateNoWindow = false;
  
      process.StartInfo.UseShellExecute = false;
  
      process.StartInfo.RedirectStandardOutput = true;
  
      process.StartInfo.FileName = "ffmpeg.exe";
  
      process.StartInfo.Arguments = Arguments;
  
  
  
      process.Start();
  
  
  
      char[] buffer = new char[854 * 480 * 3];
  
  
  
      using (StreamReader reader = process.StandardOutput)
  
      {
  
          while (!reader.EndOfStream)
  
          {
  
              reader.Read(buffer, 0, buffer.Length);
  
          }
  
      }
  
  
  
      process.WaitForExit();
  
  }

• Incorrect frame rate in video (Xuggler + MPEG 4 + H.264)

  12 novembre 2014, par Vladislav Bauer

  I have a problem with incorrect value of frame rate in output file, after converting. I made a really simple example to describe a problem :

  public static void main(String[] args) {
  
      // reader
  
      IMediaReader reader = ToolFactory.makeReader("/tmp/1/i3.avi");
  
      IMediaWriter writer = ToolFactory.makeWriter("/tmp/1/o3.mp4", reader);
  
      reader.addListener(writer);
  
  
  
      while (true) {
  
          try {
  
              final IError error = reader.readPacket();
  
              if(error != null) {
  
                  System.err.println("Error decoding packet " + error.getDescription());
  
  
  
                  if (!reader.isOpen()) {
  
                      break;
  
                  }
  
              }
  
          } catch (final Exception ex) {
  
              System.err.println("Error decoding packet " + ex.getMessage());
  
              if (!reader.isOpen()) {
  
                  break;
  
              }
  
          }
  
      }
  
  }

  Any additional parameters for video or audio streams/codecs aren’t configured .

  The input video file ("/tmp/1/i3.avi") has the following features :

  • General
    • Container : Audio Video Interleave (AVI)
  • Video
    • Dimensions : 624x352
    • Codec : XVID MPEG-4
    • Framerate : 24 frames per second
    • Bitrate : N/A
  • Audio :
    • Codec : MPEG-1 Layer 3 (MP3)
    • Channels : Stereo
    • Sample rate : 48000 Hz
    • Bitrate : 112 kbps

  The output video file ("/tmp/1/o3.avi") has the following features :

  • General
    • Container : Quicktime
  • Video
    • Dimensions : 624x352
    • Codec : H.264
    • Framerate : 8 frames per second
    • Bitrate : 378 kbps
  • Audio :
    • Codec : MPEG-4 AAC
    • Channels : Stereo
    • Sample rate : 48000 Hz
    • Bitrate : 127 kbps

  So, the frame rate in output file is 8 instead of 24. How can I fix it ? Please, help me..

  PS : I’ve already tried Xuggler H264 FPS encoding issue and few another solutions, it doesn’t help..

  ---

  UPD : After a long war with Xugler I wrote my own pure-java interface to the avconv and it works fine for me : https://github.com/vbauer/avconv4java