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• Processing Video Frames in C# (FFMPEG Slow)

  9 septembre 2020, par julian bechtold

  I am trying to extract frames out of mp4 videos in order to process them.

  


  Namely there is a watermark / timestamp within the video image which I want to use to automatically stitch the videos together. The Video creation date is not sufficient for this task.


  


  Also the part of extracting the text out of the video with AI is fine.

  


  However, FFMPEG seems terribly slow. the source Video is 1080p / 60fps (roughly 1GB per 5 Minutes of video).

  


  I have tried two methods so far using Accord.FFMPEG wrapper :

  


  public void GetVideoFrames(string path)
{
    using (var vFReader = new VideoFileReader())
    {
        // open video file
        vFReader.Open(path);
        // counter is beeing used to extract every xth frame (1 Frame per second)
        int counter = 0;
        for (int i = 0; i < vFReader.FrameCount;i ++)
        {
            counter++;
            if (counter <= 60)
            {
                _ = vFReader.ReadVideoFrame();
                continue;
            }
            else
            {
                Bitmap frame = vFReader.ReadVideoFrame();
                // Process Bitmap
            }
        }
    }
}


  


  The other attempt :

  


  for (int i = 0; i < vFReader.FrameCount;i+= 60)
{
    // notice here, I am specifying which exact frame to extract
    Bitmap frame = vFReader.ReadVideoFrame(i);
    // process frame
}


  


  The second method is what I tried first and it's totally unfeasible. Apparently FFMPEG makes a new seek for each specific frame and thus the operation takes longer and longer for each frame processed.
After 5 frames already, it takes roughly 4 seconds to produce one Frame.

  


  The first method at least does not seem to suffer from that issue as heavily but it still takes roughly 2 seconds to yield a frame. At this rate i'm faster to process the video manually.

  


  Is there anything wrong with my approach ? Also I rather don't want to have a solution where I need to separately install third party libraries on the target machine.
So, if there are any alternatives, I'd be happy to try them out but it seems litterally everyone on stack overflow is either pointing to ffmpeg or opencv.

  


• ffmpeg - error message "Invalid data found when processing input" when trying to convert a video file but video is playable

  1er septembre 2020, par Rotem

  I'm using ffmpeg version

  


  ffmpeg version 4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with Apple clang version 11.0.0 (clang-1100.0.33.8)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.2.1_1 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags='-I/Library/Java/JavaVirtualMachines/adoptopenjdk-13.jdk/Contents/Home/include -I/Library/Java/JavaVirtualMachines/adoptopenjdk-13.jdk/Contents/Home/include/darwin -fno-stack-check' --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libsnappy --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100


  


  When I try to process this video using this command

  


  ffmpeg -i IMG_0029.mp4 -y newvideo2.mp4


  


  I get this output

  


  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a1f008200] could not find corresponding trex (id 1)
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a1f008200] could not find corresponding track id 0
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a1f008200] trun track id unknown, no tfhd was found
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a1f008200] error reading header
IMG_0029.mp4: Invalid data found when processing input


  


  I don't understand what is the problem as the video is playable.

  


  Would appreciate any help.

  


• FFMPEG bottleneck in relaying data from a dshow camera to stdout PIPE without any processing or conversion

  19 août 2020, par koonyook

  I have a USB camera (FSCAM_CU135) that can encode the video to MJPEG internally and it supports DirectShow. My goal is to retrieve the binary stream of the encoded video as it is (without decoding or preview) and send it to my program for further processing.

  


  I choose to use FFMPEG to read the MJPEG stream and pipe to stdout so that I can read it using Python's subprocess.Popen .

  


  ffmpeg -y -f dshow -vsync 2 -rtbufsize 1000M -video_size 1920x1440 -vcodec mjpeg -i video="FSCAM_CU135" -vcodec copy -f mjpeg pipe:1


  


  At this resolution, the camera is able to capture and transmit at 60 fps.
In this case, I expect FFMPEG to pass the data as fast as possible with no calculation.
With the output of FFMPEG I can tell how fast it moves the data from rtbuffer to the output pipe.

  


  With just one camera, FFMPEG works with no problem and move the data at 60 fps.
However, when I run 2 cameras simultaneously, the cameras still generate data at 60 fps but FFMPEG can only move the data around 55 fps. This means that I am unable to consume the video in realtime and the buffer consumption will be larger over time.

  


  I guess that FFMPEG didn't just simply move the data but did some processing such as searching for the beginning, the end, and the timestamp of each video frame so that it can count frames and report.
Is there a way to force FFMPEG to not doing those things and focus on passing the data only to make it faster ?

  


  If I purely use directshow API without FFMPEG, can it be faster ?