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• youtube-dl - How do I ensure that the "original" video formats are downloaded ?

  25 juin 2018, par Schytheron

  I am building a C# GUI (Windows only) for youtube-dl where I allow the user to pick the desired video quality and framerate but I am having problems with format selection. youtube-dl sometimes downloads either the wrong video file or the wrong audio file (often it is audio) and after merging them I end up with a .mkv file because according to FFmpeg the files I am trying to merge are incompatible.

  These are the format selection queries I have tried to far :

  bestvideo[height<=?%height%][fps<=?%fps%]+bestaudio/best

  and

  public string[] qualities = { "4320", "2160", "1440", "1080", "720", "480", "360", "240", "144" };
  
  public string[] framerates = { "60", "50", "48", "30", "24" };
  
  private void buildFormat(int qualSkip,int fpsSkip)
  
          {
  
              string[] qualitiesMin = qualities.Skip(qualSkip).ToArray();
  
              string[] frameratesMin = framerates.Skip(fpsSkip).ToArray();
  
              format = "-f ";
  
              foreach (string quality in qualitiesMin)
  
              {
  
                  foreach (string framerate in frameratesMin)
  
                  {
  
                      format += "bestvideo[height=?" + quality + "][fps=?" + framerate + "]+bestaudio/";
  
                  }
  
              }
  
              format += "best";
  
          }

  In the first one I had a problem where on some videos youtube-dl downloaded a video in a lower framerate than what I requested (for example, if I request 1080p60FPS I get 1080p30FPS). I tried to fix this in the second method by searching for the best video for all qualities and framerates that are equal to or lower than the one I picked (for example, if I pick 1080p60FPS it would look for videos from 1080p60->1080p30->720p60->720p30->...->144p30).

  The second method however looks overly convoluted and stupid and another problem still remains. youtube-dl always picks the best audio quality no matter what video quality I choose. I want the audio quality to scale with the video quality (for example, if I pick 144p I want poor audio quality). There has got to be a better way.

  Maybe I am explaining this poorly but I basically want youtube-dl to ALWAYS (consistently) download the exact same video and audio format as the one that is displayed in the youtube video player itself for each picked video quality (see image below). How do I do that ?

  Example 1, Video and audio format codes of video in 4K (the numbers in the red circles are the format codes) :
  

  Example 2, Video and audio format of same video but this time in 720p :
  

  (should also pick a lower framerate video of same quality if that framerate is not available in the YouTube quality selector, for example 1080p30FPS in a 1080p60FPS video)

  Thanks !

• FFmpeg producing a flickering video from images

  21 juin 2018, par jjohnn91

  So I’m trying to make a video of a fractal rotating through some values, much like seen here.

  I generate the frames (1000 of them) using a different program written in Java that works just fine, so for the purposes of this scenario assume that all the images are in the target folder and also in numerical order as they need to appear in the video.

  I found the following code on the web to stitch images into a video, and I haven’t the faintest idea how it works, and when I run it, all of the images are indeed stitched into a video and placed on the desktop, but the video appears to have one specific frame just jump in at random positions. I’m not totally sure which one, but its one of the earlier frames, somewhere between 1 and 200 of the 1000.

  I’ve also tested making two half videos, one using the first 500 frames, and the other using the second 500 frames. The first video (1 -> 500) has flickering, and the second video (501 -> 1000) appears not to have flickering to my observations.

  I am seeking help in fixing the flickering behavior, and I will upload the video file to google drive later if asked. The Images are all 1920x1080, and in proper numerical order.

  Thanks in advance !

  import static org.bytedeco.javacpp.opencv_imgcodecs.*;
  
  import java.io.File; 
  
  import org.bytedeco.javacpp.avcodec;
  
  import org.bytedeco.javacv.FFmpegFrameRecorder;
  
  import org.bytedeco.javacv.OpenCVFrameConverter;
  
  public class ImageToMovie{
  
      public static void main(String []args){
  
          String imgPath="C:\\Users\\John\\Images";
  
          String vidPath="C:\\Users\\John\\Desktop\\video.mp4";
  
          String[] links=new String[new File(imgPath).listFiles().length];
  
          File f=new File(imgPath);
  
          File[] f2=f.listFiles();
  
          for(int i=0;icode>

• How to detect the real orientation of a video recorded by mobile with "auto rotate" disabled

  28 octobre 2022, par FlamingMoe

  When you record a video, the rotation metadata has 4 possible values (0, 90, 180 and 270) and it stores how the device was held when starting the recording.

  


  But mobile phones has also a feature to enable or disable "auto rotation" of screen.

  


  It's very typical, nowadays, to have that feature disable, and many people record videos with the phone horizontally, but since the "auto rotation" is disable, the metadata stores like the video was recorded as vertically.

  


  How to handle this ?