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• mpeg-dash toolkit, how can I make such videos ?

  21 mai 2015, par sathia

  I was reading about this nice specification but I’m not sure what’s the current status. Ffmpeg has some coverage

  http://ffmpeg.org/ffmpeg-all.html#webm_005fdash_005fmanifest

  but it is not clear to me if I could encode videos in such format.
  So, the question is, If I were to produce mpeg-dash compliant videos, how would I do nowadays ? thanks !

• Seeking in Libav / FFMPEG a DASH stream

  23 janvier 2018, par Glen Rhodes

  Recently, the functionality for playing DASH format files (mpd) was added to Libav. I’m trying to determine the best way to seek forward in the stream.

  When I use av_seek_frame, it does go to the correct time, but there’s a considerable delay which makes me think it’s not properly jumping to a segment / byte offset in the HTTP request, but rather just downloading with all its might until it arrives at the correct timestamp.

  int ret = av_seek_frame(is->pFormatCtx, stream_index, seek_target, is->seek_flags);

  When I use avformat_seek_file, it only seems to go forward several seconds before just continuing to play. So if I start playback, and then seek to 50 seconds, it will jump to something like 12. If I do the same seek again, it’ll jump further ahead, but still not 50.. however if it eventually gets to 50, then I do avformat_seek_file, it will successfully jump back to 50 no problem. So it’s like it tries, and gives up.

  int ret = avformat_seek_file(is->pFormatCtx, stream_index, INT64_MIN, tm, INT64_MAX, 0);

  Does anyone know how seeking is managed in the Libav dash playback ?

• Recursively convert media directory from HEVC to h.264 with ffmpeg

  8 avril 2016, par chuckcastle

  I have media server with two directories : Movies and TV Shows. Within each of those directories, each entry exists in a sub-directory which contains the video file and subtitle files.

  I’ve scoured the web and have found an excellent perl script from Michelle Sullivan, posted here :

      #!/usr/bin/perl
  
  
  
  use strict;
  
  use warnings;
  
  
  
  open DIR, "ls -1 |";
  
  while (<dir>)
  
  {
  
          chomp;
  
          next if ( -d "$_"); # skip directories
  
          next unless ( -r "$_"); # if it's not readable skip it!
  
          my $file = $_;
  
          open PROBE, "ffprobe -show_streams -of csv '$file' 2>/dev/null|" or die ("Unable to launch ffmpeg for $file! ($!)");
  
          my ($v, $a, $s, @c) = (0,0,0);
  
          while (<probe>)
  
          {
  
                  my @streaminfo = split(/,/, $_);
  
                  push(@c, $streaminfo[2]) if ($streaminfo[5] eq "video");
  
                  $a++ if ($streaminfo[5] eq "audio");
  
                  $s++ if ($streaminfo[5] eq "subtitle");
  
          }
  
          close PROBE;
  
          $v = scalar @c;
  
          if (scalar @c eq 1 and $c[0] eq "ansi")
  
          {
  
                  warn("Text file detected, skipping...\n");
  
                  next;
  
          }
  
          warn("$file: Video Streams: $v, Audio Streams: $a, Subtitle Streams: $s, Video Codec(s): " . join (", ", @c) . "\n");
  
          if (scalar @c > 1)
  
          {
  
                  warn("$file has more than one video stream, bailing!\n");
  
                  next;
  
          }
  
          if ($c[0] eq "hevc")
  
          {
  
                  warn("HEVC detected for $file ...converting to AVC...\n");
  
                  system("mkdir -p h265");
  
                  my @params = ("-hide_banner", "-threads 2");
  
                  push(@params, "-map 0") if ($a > 1 or $s > 1 or $v > 1);
  
                  push(@params, "-c:a copy") if ($a);
  
                  push(@params, "-c:s copy") if ($s);
  
                  push(@params, "-c:v libx264 -pix_fmt yuv420p") if ($v);
  
                  if (system("mv '$file' 'h265/$file'"))
  
                  {
  
                          warn("Error moving $file -> h265/$file\n");
  
                          next;
  
                  }
  
                  if (system("ffmpeg -xerror -i 'h265/$file' " . join(" ", @params) . " '$file' 2>/dev/null"))
  
                  {
  
                          warn("FFMPEG ERROR.  Cannot convert $file restoring original...\n");
  
                          system("mv 'h265/$file' '$file'");
  
                          next;
  
                  }
  
          } else {
  
                  warn("$file doesn't appear to need converting... Skipping...\n");
  
          }
  
  }
  
  close DIR;
  
  </probe></dir>

  The script performs perfectly - as long as it is run from within the directory containing the media.

  My question : Can this script be modified to run recursively from the root directory ? How ?

  Thanks in advance.

  (Michelle’s script can be seen here : http://www.michellesullivan.org/blog/1636)