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• id3 reading from mp3 files

  2 octobre 2012, par payal

  i have the below script for reading mp3 files id3.i have checked manually that id3 tags are there in mp3 files but my output always returns for few files
  MP3 file does not have any ID3 tag !. i am converting these files from ffmpeg when i run the below code for original files it shows the id3 tags but when i run for converted files (by ffmpeg) it is not showing any id3 tags . i have downloaded both original and converted file and check and found that both files is having exactly same tags but the below code give MP3 file does not have any ID3 tag !. for converted file

  here is code

   <?php
  
   $mp3 = "4.mp3"; //The mp3 file.
  
  
  
   $filesize = filesize($mp3);
  
   $file = fopen("4.mp3", "r");
  
  
  
   fseek($file, -128, SEEK_END); // It reads the 
  
  
  
   $tag = fread($file, 3);
  
  
  
   if($tag == "TAG")
  
   {
  
       $data["title"] = trim(fread($file, 30));
  
  
  
       $data["artist"] = trim(fread($file, 30));
  
  
  
       $data["album"] = trim(fread($file, 30));
  
  
  
       $data["year"] = trim(fread($file, 4));
  
  
  
        $data["genre"] = trim(fread($file, 1));
  
  
  
  
  
  
  
     }
  
     else
  
       die("MP3 file does not have any ID3 tag!");
  
  
  
     fclose($file);
  
  
  
     while(list($key, $value) = each($data))
  
     {
  
       print("$key: $value<br />\r\n");    
  
    }
  
   ?>    

• Keep blender rendered high quality images during video creation (ffmpeg)

  31 janvier 2021, par Tobi

  I created an animation in Blender and exported each frame as high quality picture. However, putting them together using ffmpeg reduces the quality (I also tried the video export from Blender but I am not an expert in video codecs and all related topics). I converted the single frames into a video by using the following command :

  


  ffmpeg -f image2 -i %4d.png -r 60 -crf 0 -vcodec libx264 blenderVideo.mp4

  


  The resulting frame from the video is given in the picture below. As one can see, the shining rings are clearly visible but in the original picture it is completely smooth. Any idea how to overcome this problem ? Maybe it is stupid to think that I can get the original qualities. Probably, if I upload it somewhere, it gets compressed in any case and it is not worth to investigate into that topic too much. However, I am interested and there are specialists out who can directly tell if it is worth or not.

  


  

  


• FFmpeg concat protocol and keyframes

  11 janvier 2023, par Rems

  I am trying to use to the concat protocol but I have troubles with keyframes

  


  I use this ffprobe command to visualize the keyframes pts of my videos :

  


  ffprobe -loglevel error -select_streams v:0 -show_entries packet=pts_time,flags -of csv=print_section=0 inout.mp4  | awk -F',' '/K/ {print $1}'

  


  Here is my process : I have the original video, with these keyframes :

  


  0.000000 5.000000 9.760000 14.240000  18.440000 ...

  


  I trim the first 5 seconds, so the output has these keyframes :

  


  0.000000 4.760000 9.240000 13.440000 ...

  


  I create a 5 seconds video by looping an image, with the same parameters/codec... that were used to produce the original video. This video just has one keyframe at 0.000000

  


  Then I concat this video with the trimmed video like this :

  


  ffmpeg -f concat -safe 0 -i list.txt -c copy -shortest  output.mp4 -y

  


  But when I look for the keyframes of the output video, I get this :

  


  0.021016 5.035000 9.795000 14.275000 ...

  


  Is this behavior normal ? Should I add a parameter to handle keyframes during concatenation ? Thanks