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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 ?

• Howto extract blackframes and volumes info from video at the same time with ffmpeg/ffprobe

  3 novembre 2019, par Alexander Kislitsky

  I’m extracting astats info with :

  ffprobe -f lavfi -i "amovie=video.flv,astats=metadata=1:reset=1" -show_entries frame=pkt_pts_time:frame_tags -print_format json

  Blackframes info with :

  ffprobe -f lavfi -i "movie=video.flv,blackframe=1" -show_entries frame=pkt_pts_time:frame_tags -print_format json

  But when I’m trying to combine filters like this :

  ffprobe -f lavfi -i "amovie=video.flv,astats=metadata=1:reset=1;movie=video.flv,blackframe=1" -show_entries frame=pkt_pts_time:frame_tags -print_format json

  I’ve the following error : Invalid filterchain containing an unlabelled output pad : "astats=metadata=1:reset=1 ;movie=video.flv,blackframe=1"

  How to combine output of two filters in a single json file ?

• Decrypt or decode ultraviolet videos

  29 mai 2017, par argetlam5

  I was on Vudu because I have some Ultraviolet movies in my collection and I saw you could download them from their site for offline usage.

  The files on the computer from that download are an h264-2000.mp4 file and aac-256.mp4 file (along with a json subtitle file and some other meta data stuff). When I try to run them individually however nothing happens and when I try to convert to m4v with ffmpeg it fails.

  • Are these files encrypted so that only their video player can play it ?
  • Is there a way to combine all of these files that I’m just not aware of ?

  Vudu uses Adobe Air if that gives you any more information.

  Also, if it is encrypted, does that mean it’s illegal for me to try to be messing with these ? I thought since I bought the movie it would be fine to try. I know I could rip the movie with something like handbrake but the quality from Vudu & other Ultraviolet sites is really nice and my computer doesn’t have a bluray reader to try and rip from a bluray.