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• AForge.Video.VideoFileWriter, Video Quality loss after a second

  29 décembre 2019, par Just another Dev

  I tried to use AForge to create mp4 video from images..but experience this quality loss after about 1 - 2 second into the video. Just wondering if anyone knows what went wrong with my code ?

  using AForge.Video.FFMPEG;
  
  VideoFileWriter writer = new VideoFileWriter();
  
  writer.Open(fileName, _width, _height, _frameRate, VideoCodec.MPEG4, 800000);
  
  var s = AForge.Imaging.Image.FromFile(@"[path]\image.jpg");
  
  int frameCount = _frameRate * scene.Time;
  
  for (int i = 0; i < frameCount; i++)
  
  {
  
      writer.WriteVideoFrame(s);
  
  }
  
  writer.Close();

  I use the above code to create a 3 second 1080p video with frame rate 60, bit rate 800k, and using this image as an example : https://www.bushandbeach.co.nz/wp-content/uploads/2019/05/A-Taste-of-Auckland-Full-Day-1-opt.jpg

  the output video is in here : https://youtu.be/j0z7711cyOM

  as you can see the image quality seems to be ok, for about 2 seconds and then it blurs out in the last second.

  Thanks so much

• ffmpeg-python crossfade transition for unknown number of photos

  28 septembre 2020, par Saya

  I want to convert a bunch of photos into a video with crossfade between them. The number of photos I am converting is variable
I am using the code from HERE to apply the crossfade :

  


  Since the number of photos are variable I looped over all the photos in the directory and generated the -loop and also the second part ([0:v]fade=t=out:st=4:d=1[v0] ;) :

  


  for i in range(os.listdir('photos')):
    if i == 0:
        text += f'\n-loop 1 -t 60 -i photos/Image{i+1}.jpg \\\n'
        text2 = '\n[0:v]fade=t=out:st=4:d=1[v0]; \\\n'
    else:
        text += f'-loop 1 -t 60 -i photos/Image{i+1}.jpg \\\n'
        text2 += f' [{i}:v]fade=t=in:st=0:d=1,fade=t=out:st=4:d=1[v{i}]; \\\n'

#And the Subprocess part  

command = f'ffmpeg \
    {text} \
    -filter-complex \
    {text2} -map "[v]" video/out.mp4'
p = subprocess.call(command, shell=True) 


  


  But this thing didn't create any video but said this :

  


  Use -h to get full help or, even better, run 'man ffmpeg'


  


  The full output :

  


  ffmpeg version git-2019-11-11-20c5f4d Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9.2.1 (GCC) 20191010
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 35.101 / 56. 35.101
  libavcodec     58. 61.100 / 58. 61.100
  libavformat    58. 34.101 / 58. 34.101
  libavdevice    58.  9.100 / 58.  9.100
  libavfilter     7. 66.100 /  7. 66.100
  libswscale      5.  6.100 /  5.  6.100
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Hyper fast Audio and Video encoder
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...

Use -h to get full help or, even better, run 'man ffmpeg'


  


• Gallery of VP8 Encoding Naivete

  15 octobre 2010, par Multimedia Mike — VP8

  I’ve been toiling away as a multimedia technology generalist for so long that it’s easy for me to forget that not everyone is as versed in the minutiae of the domain as I am. But I recently experienced what it’s like to be such an outsider when I posted about my toy VP8 encoder, expressing that it’s one of the hardest things I have ever tried to do. I heard of from number of people who do have extensive experience in video encoding, particularly with the H.264 and VP8 codecs. Their reactions were predictable : What’s so hard ? Look, you might be a little too immersed in the area to really understand a relative beginner’s perspective.

  And to all the people who suggested that I should get the encoder into FFmpeg ASAP : Are you crazy ?! Did you see what the first pass of the encoder produced ? Do you have lower standards than even I do ?

  
  
  

  Not Giving Up
  I worked a little more on the toy encoder. Remember that the above image is what I’m hoping to encode somewhat faithfully for this experiment. In my first pass, I attempted vertical prediction for all planes. For my next pass, I forced the chroma planes to mid-level (which results in a greyscale image) and played with the 16×16 luma prediction modes. When implementing an extremely naive algorithm to decide which 16×16 prediction mode would be the best for a particular block, this is what the program produced :

  
  
  

  For fun, here is what the image encodes to when forcing various prediction modes :
  

  I think the DC-only prediction mode actually looks a little better than the image that the naive algorithm produced :

  
  
  

  Vertical 16×16 prediction, similar to the image from the last post (just in black and white) :
  

  
  
  

  Horizontal 16×16 prediction :
  

  
  
  

  This is the 16×16 prediction mode unique to VP8, the TrueMotion mode (based on On2/Duck’s very first video codec) :
  

  
  
  

  Wow, these encodings really bring down the cheerful tone of the original image.

  Next Steps
  I have little reason to believe that I am encoding and subsequently reconstructing the image correctly (i.e., error is likely propagating through the entire encoding). If I have time, the next step is to validate my reconstruction against the encoder. Then I need to get the entropy considerations correct so that I actually get some compression out of this format.