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• Shifting audio in MPEG4 content and manipulating atoms

  10 janvier 2018, par LLL

  1. Shift audio

  I use ffmpeg / avconv quite often ... and usually I hate it.
  Those tools do what they are instructed to do about 30% of the time. I could give you countless examples but I don’t want to start flame war, so please help me with my current problem (really easy one).

  I wanted to shift audio (content is standard mp4 file with aac and h264 tracks), so I have found a "highly upvoted" solution :

  https://superuser.com/a/983153/758887

  the only problem with it is that it doesn’t work. I downloaded latest stable ffmpeg (even on windows as in the thread, so it’s version was 3.4.1) and executed command without changing literaly anything :

  ffmpeg.exe -i "movie.mp4" -itsoffset 3.84 -i "movie.mp4" -map 0:v -map 1:a -vcodec copy -acodec copy "movie-audio-delayed.mp4"

  Result was no shift (I expected audio to be 3.84s late).

  2. Remove MPEG4 atoms

  I would be also grateful if you could recommend some tool for removing MPEG4 boxes from content. For examining MPEG4 content I use MP4 Explorer / Codec Visa (limited) on Windows and AtomicParsley on Linux, however they only print atoms and I would like to edit / remove them. For example MP4Box can remove whole moov->track with "-rem" option but what if I would like to remove moov->track->edts only ?

• How can I use FFMpeg with PHP in a Vagrant environment ?

  31 juillet 2015, par curtisblackwell

  I’ve got this working on a DigitalOcean server, but I can’t seem to get it working locally.

  My Vagrant box is ubuntu/trusty64. When I ssh into the machine to check out the permissions of the ffmpeg binary, it’s 664. I tried running chmod 755 ffmpeg (w/ and w/o sudo), but it has no effect and outputs no response. I’m the owner, so chown wouldn’t make any difference (but also doesn’t work, w/ or w/o sudo). Outside of the Vagrant machine, the file permissions are 755 and owned by me, though that doesn’t seem to matter.

  The binaries are static builds from a site linked to on the official FFMpeg site’s download page.

  Running cat /etc/*-release on both the remote DO server and the Vagrant machine returns the same result :

  DISTRIB_ID=Ubuntu
  
  DISTRIB_RELEASE=14.04
  
  DISTRIB_CODENAME=trusty
  
  DISTRIB_DESCRIPTION="Ubuntu 14.04.2 LTS"
  
  NAME="Ubuntu"
  
  VERSION="14.04.2 LTS, Trusty Tahr"
  
  ID=ubuntu
  
  ID_LIKE=debian
  
  PRETTY_NAME="Ubuntu 14.04.2 LTS"
  
  VERSION_ID="14.04"
  
  HOME_URL="http://www.ubuntu.com/"
  
  SUPPORT_URL="http://help.ubuntu.com/"
  
  BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"

  When attempting to execute the binary through PHP on the Vagrant machine (with exec()), I get a 126 exit code.

  What else should I try to get this working ?

• movenc : Don’t assume that fragment durations in pts is equal to duration in dts

  15 mars 2015, par Martin Storsjö

  movenc : Don’t assume that fragment durations in pts is equal to duration in dts
  For strict CFR, they should be pretty much equal, but if the stream
  
  is VFR, there can be a sometimes significant difference.
  Calculate the pts duration separately, used in sidx atoms and for
  
  tfrf/tfxd boxes in smooth streaming ismv files.
  Also make sure to reduce the duration of sidx entries according to
  
  edit lists.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavformat/movenc.c
  • [DBH] libavformat/movenc.h