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• Image edited and saved in C# can not be read by ffmpeg

  13 juillet 2017, par mmijic

  I have template image (template.jpg) on which I draw some text (13.07.2017.) and than I save it to another location (temp/intro.jpg).

  Than I want to convert that and some other images into video with ffmpeg.

  If I run command

  ffmpeg.exe -f concat -safe 0 -i input.txt -c:v libx264 -vf "fps=25,format=yuv420p" out.mp4

  Those images gets concentrated into one video file. Problem is that this image edited through C# is black in final video.

  If I for example open that C# created image in Adobe Fireworks and just save it (CTRL+S) without changing anything, and re run ffmpeg command everything is fine.

  This is code which I use to add text to template image

  //INTRO IMAGE CREATION
  
  Bitmap image = new Bitmap(1280, 720);
  
  image.SetResolution(image.HorizontalResolution, image.VerticalResolution);
  
  Graphics g = Graphics.FromImage(image);
  
  g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
  
  g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
  
  g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
  
  g.TextRenderingHint = TextRenderingHint.AntiAliasGridFit;
  
  StringFormat format = new StringFormat()
  
  {
  
      Alignment = StringAlignment.Near,
  
      LineAlignment = StringAlignment.Near
  
  };
  
  
  
  //template
  
  Bitmap back = new Bitmap(Application.StartupPath + @"\Templates\template.jpg");
  
  g.DrawImage(back, 0, 0, image.Width, image.Height);
  
  
  
  //date
  
  string Date = dateIntro.Value.ToString("dd.MM.yyyy.");
  
  var brush = new SolidBrush(Color.FromArgb(255, 206, 33, 39));
  
  Font font = new Font("Ubuntu", 97, FontStyle.Bold, GraphicsUnit.Pixel);
  
  float x = 617;
  
  float y = 530;
  
  
  
  g.DrawString(Date, font, brush, x, y, format);
  
  g.Flush();
  
  image.Save(Application.StartupPath + @"\temp\intro.jpg", ImageFormat.Jpeg);
  
  image.Dispose();

  Image created this way can be opened and viewed in any program except converted to video with ffmpeg.

  Is there anything I’m missing while adding text and saving image in C# ?

• Create Panorama from Non-Sequential Video Frames

  6 mai 2021, par M.Innat

  There is a similar question (not that detailed and no exact solution).

  


  ---

  


  I want to create a single panorama image from video frames. And for that, I need to get minimum non-sequential video frames at first. A demo video file is uploaded here.

  


  What I Need

  


  A mechanism that can produce not-only non-sequential video frames but also in such a way that can be used to create a panorama image. A sample is given below. As we can see to create a panorama image, all the input samples must contain minimum overlap regions to each other otherwise it can not be done.

  


  

  


  So, if I have the following video frame's order

  


  A, A, A, B, B, B, B, C, C, A, A, C, C, C, B, B, B ...


  


  To create a panorama image, I need to get something as follows - reduced sequential frames (or adjacent frames) but with minimum overlapping.

  


       [overlap]  [overlap]  [overlap] [overlap]  [overlap]
 A,    A,B,       B,C,       C,A,       A,C,      C,B,  ...


  


  What I've Tried and Stuck

  


  A demo video clip is given above. To get non-sequential video frames, I primarily rely on ffmpeg software.

  


  Trial 1 Ref.

  


  ffmpeg -i check.mp4 -vf mpdecimate,setpts=N/FRAME_RATE/TB -map 0:v out.mp4


  


  After that, on the out.mp4, I applied slice the video frames using opencv

  


  import cv2, os 
from pathlib import Path

vframe_dir = Path("vid_frames/")
vframe_dir.mkdir(parents=True, exist_ok=True)

vidcap = cv2.VideoCapture('out.mp4')
success,image = vidcap.read()
count = 0

while success:
    cv2.imwrite(f"{vframe_dir}/frame%d.jpg" % count, image)     
    success,image = vidcap.read()
    count += 1


  


  Next, I rotated these saved images horizontally (as my video is a vertical view).

  


  vframe_dir = Path("out/")
vframe_dir.mkdir(parents=True, exist_ok=True)

vframe_dir_rot = Path("vframe_dir_rot/")
vframe_dir_rot.mkdir(parents=True, exist_ok=True)

for i, each_img in tqdm(enumerate(os.listdir(vframe_dir))):
    image = cv2.imread(f"{vframe_dir}/{each_img}")[:, :, ::-1] # Read (with BGRtoRGB)
    
    image = cv2.rotate(image,cv2.cv2.ROTATE_180)
    image = cv2.rotate(image,cv2.ROTATE_90_CLOCKWISE)

    cv2.imwrite(f"{vframe_dir_rot}/{each_img}", image[:, :, ::-1]) # Save (with RGBtoBGR)


  


  The output is ok for this method (with ffmpeg) but inappropriate for creating the panorama image. Because it didn't give some overlapping frames sequentially in the results. Thus panorama can't be generated.

  
 


  Trail 2 - Ref

  


  ffmpeg -i check.mp4 -vf decimate=cycle=2,setpts=N/FRAME_RATE/TB -map 0:v out.mp4


  


  didn't work at all.

  


  Trail 3

  


  ffmpeg -i check.mp4 -ss 0 -qscale 0 -f image2 -r 1 out/images%5d.png


  


  No luck either. However, I've found this last ffmpeg command was close by far but wasn't enough. Comparatively to others, this gave me a small amount of non-duplicate frames (good) but the bad thing is still do not need frames, and I kinda manually pick some desired frames, and then the opecv stitching algorithm works. So, after picking some frames and rotating (as mentioned before) :

  


  stitcher = cv2.Stitcher.create()
status, pano = stitcher.stitch(images) # images: manually picked video frames -_- 


  
 


  Update

  


  After some trials, I am kinda adopting the non-programming solution. But would love to see an efficient programmatic approach.

  


  On the given demo video, I used Adobe products (premiere pro and photoshop) to do this task, video instruction. But the issue was, I kind of took all video frames at first (without dropping to any frames and that will computationally cost further) via premier and use photoshop to stitching them (according to the youtube video instruction). It was too heavy for these editor tools and didn't look better way but the output was better than anything until now. Though I took few (400+ frames) video frames only out of 1200+.

  


  

  


  ---

  


  Here are some big challenges. The original video clips have some conditions though, and it's too serious. Unlike the given demo video clips :

  


  

  • It's not straight forward, i.e. camera shaking

  


  • Lighting condition, i.e. causes different visual look at the same spot

  


  • Cameral flickering or banding

  


  


  This scenario is not included in the given demo video. And this brings additional and heavy challenges to create panorama images from such videos. Even with the non-programming way (using adobe tools) I couldn't make it any good.

  


  ---

  


  However, for now, all I'm interest to get a panorama image from the given demo video which is without the above condition. But I would love to know any comment or suggestion on that.

  


• ffmpeg recoded mp4 files error on mobiles in Video JS

  10 janvier 2019, par KJS

  We are converting seriously old .flv files to MP4 with FFMPEG. These are at least 10 years old.
  Back then all were rendered with early versions of Adobe Premiere.

  On desktop browsers all the files work and stream (...watching them feels like going back a century !)

  But when requesting the videos on the same pages on mobile devices (android and ios) Video JS doesn’t even show up.
  Perhaps the codec is just too old, but I was wondering if there could be another reason when converting them with this line :

  for i in *.flv; do ffmpeg -i "$i" "${i%.*}.mp4"; done

  If not, is it possible to detect this in Video JS, so we can show an announcement that the video is only visible on desktops ?

  I hope someone here has this knowledge !

  added on request of llogan

  ffmpeg version N-78967-gbaec6d8 Copyright (c) 2000-2016 the FFmpeg developers   built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-4)   configuration: --prefix=/root/ffmpeg_build
  
  --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags=-L/root/ffmpeg_build/lib --bindir=/root/bin --pkg-config-flags=--static --enable-gpl --enable-nonfree --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265   libavutil      55. 19.100 / 55. 19.100   libavcodec     57. 28.100 / 57. 28.100   libavformat    57. 28.100 / 57. 28.100   libavdevice    57.  0.101 / 57.  0.101   libavfilter     6. 39.102 / 
  
  6. 39.102   libswscale      4.  0.100 /  4.  0.100   libswresample   2.  0.101 /  2.  0.101   libpostproc    54.  0.100 / 54.  0.100 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'a_4293_06.mp4':   Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf57.28.100   Duration: 00:01:40.10, start: 0.023220, bitrate: 492 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 320x240, 376 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 123 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler At least one output file must be specified