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• resolution changed mid video - FFMPEG

  27 août 2012, par user1626099

  I have a source video (mpeg2video) which I'm transcoding to x264. The source contains 2 different programs recorded from TV. One is in 4:3 AR and the other 16:9 AR. When I play the source file through VLC the player correctly changes size to show the video at the correct AR. So far so good.

  When I transcode the conversion process auto detects the AR from the first few frames and then transcodes the whole video using this AR. If the 16:9 section comes first then the whole conversion is done in 16:9 and the 4:3 section looks stretch horizontally. If the 4:3 section is at the start of the source file then the whole transcode is done in 4:3 and the 16:9 section looks squashed horizontally.

  No black bars are ever visible.

  Here's my command :

  nice -n 17 ffmpeg -i source.mpg -acodec libfaac -ar 48000 -ab 192k -async 1 -copyts -vcodec libx264 -b 1250k -threads 2 -level 31 -map 0:0 -map 0:1 -map 0:2 -scodec copy -deinterlace output.mkv

  I don't fully understand what's going on. How do I get the same 'change in AR' mid video in the output file that I have in the input video ?

• How to deal with cv::VideoCapture decode errors ?

  24 février 2016, par George Profenza

  I’m streaming H264 content from an IP camera using the VideoCapture from OpenCV (compiled with ffmpeg support).

  So far things work ok, but every once in a while I get decoding errors (from ffmpeg I presume) :

  [h264 @ 0x103006400] mb_type 137 in I slice too large at 26 10
  
  [h264 @ 0x103006400] error while decoding MB 26 10
  
  [h264 @ 0x103006400] negative number of zero coeffs at 25 5
  
  [h264 @ 0x103006400] error while decoding MB 25 5
  
  [h264 @ 0x103006400] cbp too large (421) at 35 13
  
  [h264 @ 0x103006400] error while decoding MB 35 13
  
  [h264 @ 0x103006400] mb_type 121 in P slice too large at 20 3
  
  [h264 @ 0x103006400] error decoding MB 20 3

  These messages show up in the console. Is there any clean way to listen to these ? I’d like to skip processing the glitchy frames.

  Any hints/tips ?

• ffmpeg Progress Bar - Encoding Percentage in PHP

  11 juillet 2016, par Jimbo

  I’ve written a whole system in PHP and bash on the server to convert and stream videos in HTML5 on my VPS. The conversion is done by ffmpeg in the background and the contents is output to block.txt.

  Having looked at the following posts :

  Can ffmpeg show a progress bar ?

  and

  ffmpeg video encoding progress bar

  amongst others, I can’t find a working example.

  I need to grab the currently encoded progress as a percentage.

  The first post I linked above gives :

  $log = @file_get_contents('block.txt');
  
  
  
  preg_match("/Duration:([^,]+)/", $log, $matches);
  
  list($hours,$minutes,$seconds,$mili) = split(":",$matches[1]);
  
  $seconds = (($hours * 3600) + ($minutes * 60) + $seconds);
  
  $seconds = round($seconds);
  
  
  
  $page = join("",file("$txt"));
  
  $kw = explode("time=", $page);
  
  $last = array_pop($kw);
  
  $values = explode(' ', $last);
  
  $curTime = round($values[0]);
  
  $percent_extracted = round((($curTime * 100)/($seconds)));
  
  
  
  echo $percent_extracted;

  The $percent_extracted variable echoes zero, and as maths is not my strong point, I really don’t know how to progress here.

  Here’s one line from the ffmpeg output from block.txt (if it’s helpful)

  time=00:19:25.16 bitrate= 823.0kbits/s frame=27963 fps= 7 q=0.0 size=
  117085kB time=00:19:25.33 bitrate= 823.1kbits/s frame=27967 fps= 7
  q=0.0 size= 117085kB time=00:19:25.49 bitrate= 823.0kbits/s
  frame=27971 fps= 7 q=0.0 size= 117126kB

  Please help me output this percentage, once done I can create my own progress bar. Thanks.