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• AVFormatContext : interrupt callback proper usage ?

  17 juillet 2021, par Daniel

  AVFormatContext's interrupt_callback field is a

  


  


  Custom interrupt callbacks for the I/O layer.

  


  


  It's type is AVIOInterruptCB, and it explains in comment section :

  


  


  Callback for checking whether to abort blocking functions.

  


  AVERROR_EXIT is returned in this case by the interrupted function. During blocking operations, callback is called with opaque as parameter. If the callback returns 1, the blocking operation will be aborted.

  


  No members can be added to this struct without a major bump, if new elements have been added after this struct in AVFormatContext or AVIOContext.

  


  


  I have 2 questions :

  


  

  1. what does the last section means ? Especially "without a major bump" ?

  


  2. If I use this along with an RTSP source, when I close the input by avformat_close_input, the "TEARDOWN" message is being sent out, however it won't reach the RTSP server.

  


  


  For 2 : here is a quick pseudo-code for demo :

  


  int pkts = 0;
bool early_exit = false;

int InterruptCallback(void* ctx) {
    return early_exit ? 1 : 0;
}

void main() {
  ctx = avformat_alloc_context
  ctx->interrupt_callback.callback = InterruptCallback;

  avformat_open_input
  avformat_find_stream_info
  pkts=0;
  while(!early_exit) {
    av_read_frame

    if (pkts++ > 100) early_exit=true;
  }

  avformat_close_input
}


  


  In case I don't use the interrupt callback at all, TEARDOWN is being sent out, and it also reaches the RTSP server so it can actually tear down the connection. Otherwise, it won't tear down it, and I have to wait until TCP socket times out.

  


  What is the proper way of using this interrupt callback ?

  


• Combining Audio and Video file in python [duplicate]

  8 juin 2020, par yso

  I'm trying to understand how to us ffmpeg to combine video and audio files in python. I want to combine a .avi file and a .wav file to create a final .avi file. Is this the right approach ? I'm confused by the ffmpeg syntax.
Any help would be great.

  



  I was looking through this for help :
https://wiki.libav.org/Snippets/avconv#Combine_audio_and_video_file

  



  import ffmpeg
import subprocess

cmd = 'ffmpeg -i inputvideo.avi -i inputaudio.wav -c:v copy -c:a aac output_video_and audio.avi'
subprocess.call(cmd, shell=True)                                     # "Muxing Done
print('Muxing Done')


  


• ffmpeg Error : Pattern type 'glob' was selected but globbing is not support ed by this libavformat build

  14 septembre 2017, par Aryan Naim

  I’m trying to convert group of ".jpg" files acting as individual frames into 1 single mpeg video ".mp4"

  Example parameters i used :

  frame duration  = 2 secs
  
  frame rate      = 30  fps
  
  encoder         = libx264 (mpeg)
  
  input pattern   = "*.jpg"
  
  output pattern  = video.mp4

  Based on ffmpeg wiki instructions at (https://trac.ffmpeg.org/wiki/Create%20a%20video%20slideshow%20from%20images), I issued this command :

  ffmpeg -framerate 1/2 -pattern_type glob -i "*.jpg" -c:v libx264 -r 30 -pix_fmt yuv420p video.mp4

  But I’m getting this error :

  [image2 @ 049ab120] Pattern type 'glob' was selected but globbing is not 
  
  supported by this libavformat build *.jpg: Function not implemented

  Which probably means the API pattern matching commands for my build/version have changed. By the way this my windows 32bit ffmpeg download build (ffmpeg-20150702-git-03b2b40-win32-static).

  How can I choose a group of files using pattern matching using ffmpeg ?