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• ffmpeg : How to set AVFormatContext from NSData

  21 janvier 2014, par SUKIYAKI

  I'm using FFmpeg library in Objective-C.

  I want to set AVFormatContext from NSData which contain imagedata.
  I know I can set AVFormatContext with av_open_input_file().
  so writing contents of NSData to a temporary file, I can do it like this.

  [data writeToFile:@"./temp.mov" atomically:YES];
  
  av_open_input_file(&pFormatCtx, "./temp.mov", NULL, 0, NULL);
  
  
  
  .
  
  .
  
  .
  
  
  
  NSFileManager *fm = [NSFileManager defaultManager];
  
  [fm removeFileAtPath:@"./temp.mov" handler:nil];

  but, I don't want to use temporary file.

  Does anyone know smart way ?

  sorry my poor English.

  Thanks

• ffmpeg override the same file for every second of the video [on hold]

  5 février 2017, par Dorin Pleava

  I want to get one image for every 10 seconds from a livestream/video, but the image should have the same name, meaning I want to override it every cycle.

  This is my command :

  ffmpeg.exe -i http://iphone-streaming.ustream.tv/uhls/17074538/streams/live/iphone/playlist.m3u8 -bt 20M -s 480x300 -vf fps=1/10 -y photo.jpg

  This code works for one image but for the next I get this

  "Could not get frame filename number 2 from pattern ’photo.jpg’ (either set updatefirst or use a pattern like %03d within the filename pattern)
  av_interleaved_write_frame() : Invalid argument"

  If I replace photo.jpeg with photo%03d.jpg I get photo001.jpec, followed by photo002.jpeg, etc.

• Issue regarding concatenate videos ffmpeg

  8 février 2021, par Mayank Thapliyal

  I want to concatenate 3 videos using ffmpeg. So I did a research on the net and got the required code. But later on I realized that it will not work as the attributes of the video are different and hence I will have to re-encode the videos

  


  So I got this on the internet :-

  


  ffmpeg -i 1.mp4-i 2.mp4 -i 3.mp4 -filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a] concat=n=3:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" output.mp4

  


  But when I ran it,it was SUPER slow. And ffmpeg recommended to add vsync 2 in the code. I added it in the following manner :-

  


  ffmpeg -i 1.mp4-i 2.mp4 -i 3.mp4 -vsync 2 -filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a] concat=n=3:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" output.mp4

  


  Now the video was processed on time and the result was also fine. But I don't know the meaning of the code. Will someone be kind enough to explain what exactly is happening ? (in this way I would be sure that the code will always work for me for all videos)