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• avio_tell() return value doesn't change after avformat_seek_file()

  31 juillet 2024, par user3133806

  I have a C++ program that seeks into a video file.

  


  The C++ code looks like the following :

  


  int64_t before = avio_tell(formatContext);
int status = avformat_seek_file(formatContext, streamIndex, INT64_MIN, desiredPts, 
desiredPts, 0);
CHECK_EQ(status, 0);
avio_flush(formatContext->pb);
int64_t after = avio_tell(formatContext);

std::cout << "before=" << before << " after=" << after << std::endl;


  


  The seek is successful. However, before and after are the exact same value.

  


  In fact from my testing it seems like avio_tell() only returns a different value after avformat_read_frame().

  


  The underlying problem I am trying to solve is very similar to this : How to seek with avformat_seek_file() but only if the seek jumps forward ?

  


  My strategy was going to be :

  


  

  1. Get the position using avio_tell()

  


  2. Seek using avformat_seek_file()

  


  3. Get the new position using avio_tell(). If it seeked backwards, undo the seek by doing a manual seek to the position from (1).

  


  


  But this strategy doesn't work because avio_tell() doesn't change its return value after avformat_seek_file().

  


  Any input would be appreciated.

  


• ffmpeg Windows stream desktop real time to web

  14 avril 2019, par ilapasle

  Hello i want to stream my Windows desktop in realtime with ffmpeg

  for capture desktop i use this code :

  ffmpeg.exe -f gdigrab -framerate 60 -i desktop output.mkv

  it’s work

  Now i not want to record video of my desktop but stream my desktop and view this in web browser.
  i need to export stream video in m3u8 file

  i have use this code :

  ffmpeg.exe -f gdigrab -framerate 60 -i desktop -c:v libx264 -crf 18 -maxrate 400k -bufsize 1835k -pix_fmt yuv420p -hls_time 10 -hls_wrap 6 output.m3u8

  in my current dir i have 6 ts file and output.m3u8 but i can not open output.m3u8 file, the file is empty why ?

  i want to read this file in web browser like this code :

      
  
  
  
  
  
  
  
  <div>
  
  <video autoplay="true" controls="controls" width="640" height="480">
  
  <source src="output.m3u8" type="application/x-mpegURL"></source>
  
  Your browser does not support HTML5 streaming!
  
  </video>
  
  </div>

  thanks for advance for your help

• Trouble getting HTML5 vidio to play, in Firefox 33

  16 janvier 2015, par Randy

  I’m preparing to update some old pages to HTML5, and was surprised to see that it worked in Chrome, but not the latest Firefox (v.33.1... also tried v.32). What is odd is this... In Firefox it actually WILL play IF you "coax it". If you move the video position slider to someplace beyond the start (about 5 seconds in) and THEN click play, all is well. Further inspection showed that when I click play, the file pointer was jumping to the end of the file leaving my "poster" photo intact, leading the viewer to think there is nothing else they can do. If, however, you manually move the pointer back to anyplace beyond the first couple of seconds of the file (really !), and THEN click the PLAY button, FF will play the rest of the video fine.

  Sometimes i think that to the more technically minded among us, the universe doles out the weirder problems, while God laughs.

  I’d suspect video file corruption, but all my conversions were made with the very reliable ffmpeg utility, and tested with VLC. Again, it works fine from Chrome, which supposedly uses the same video format. Here’s a link...

  FF will play the older type ogv files, so if this is one of those things where FF, now at version 33 is at fault, I’ll have to detect the browser and write the order myself with a document.write(). But it would be nice to know if there is a more straigh forward solution.

  Note that I have tried adding the mime types to my HTACESS file. But the fact that the behavior is the same when point my browsers directly the file on my local machine, makles me doubt that is the problem.

  http://pixyland.org/peterpan/OurWedding2a.html

  And here is the page code

    
  
  
  
  
  
  
  
      
  
  
  
      
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  <table align="center" border="1"><tr><td align="center">
  
  <div align="center">
  
  
  
  <video width="640" height="480" controls="controls" poster="Imagezz/Wedding/arIMG_2280.JPG">
  
   <source src="../vids/Arrival.mp4" type="video/mp4">  
  
   <source src="../vids/Arrival.webm" type="video/webm"> 
  
   <source src="../vids/Arrival.ogv" type="video/ogg"> 
  
  
  
  
  
   
  
   <p>If you are unable to view the video, here are some links to download <br />
  
    in a a few well supported video formats. You may be able to just download <br />
  
    and play one of these files without the browser.<br /><br />
  
    <strong>Download Video:</strong>nbsp;
  
      nbsp;<a href="http://stackoverflow.com/feeds/vids/Arrival.mp4">"MP4"</a>
  
      nbsp;<a href="http://stackoverflow.com/feeds/vids/Arrival.webm">"WEBM"</a>
  
      nbsp;<a href="http://stackoverflow.com/feeds/vids/Arrival.ogv">"Ogg"</a>
  
   </p>
  
  
  
   </source></source></source></video>
  
   </div>
  
   </td></tr></table>