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• Start of video is not labeled as "0" in QuickTime Video from GoPro

  26 mars 2020, par John Terragnoli

  I’m trying to combine four GoPro videos into a single video, and then rotate it 90 degrees. However, the time scales on the bottom of the videos are all wrong. The videos are 17 minutes and 42 second. But the beginning time is labeled as 5:15:20:32 and the ending time is 5:33:01:32. It just looks really weird and I’d like to fix it. After I use ffmpeg to rotate and concatenate the videos, the problem persists. Could it possibly be fixed with Exiftool ?

  ffmpeg -safe 0 -f concat -i list.txt -vcodec copy -acodec copy merged_videos.MP4

  ffmpeg -i input.mov -vf "transpose=1" output.mov

  Here is the exiftool information on one of the videos :

  File Name                       : GOPR3023.MP4
  
  Directory                       : .
  
  File Size                       : 3.7 GB
  
  File Modification Date/Time     : 2018:04:12 14:56:16-05:00
  
  File Access Date/Time           : 2020:03:25 12:17:18-05:00
  
  File Inode Change Date/Time     : 2020:03:25 17:57:04-05:00
  
  File Permissions                : rwxrwxrwx
  
  File Type                       : MP4
  
  File Type Extension             : mp4
  
  MIME Type                       : video/mp4
  
  Major Brand                     : MP4 v1 [ISO 14496-1:ch13]
  
  Minor Version                   : 2013.10.18
  
  Compatible Brands               : mp41
  
  Movie Data Size                 : 4001979951
  
  Movie Data Offset               : 28
  
  Movie Header Version            : 0
  
  Create Date                     : 2018:04:12 14:38:32
  
  Modify Date                     : 2018:04:12 14:38:32
  
  Time Scale                      : 60000
  
  Duration                        : 0:17:42
  
  Preferred Rate                  : 1
  
  Preferred Volume                : 100.00%
  
  Preview Time                    : 0 s
  
  Preview Duration                : 0 s
  
  Poster Time                     : 0 s
  
  Selection Time                  : 0 s
  
  Selection Duration              : 0 s
  
  Current Time                    : 0 s
  
  Next Track ID                   : 6
  
  Firmware Version                : HD5.03.02.51.00
  
  Lens Serial Number              : NAH6092300301117
  
  Camera Serial Number Hash       : 34676f2cdf49b86a1514817a93377bf7
  
  Track Header Version            : 0
  
  Track Create Date               : 2018:04:12 14:38:32
  
  Track Modify Date               : 2018:04:12 14:38:32
  
  Track ID                        : 1
  
  Track Duration                  : 0:17:42
  
  Track Layer                     : 0
  
  Track Volume                    : 0.00%
  
  Image Width                     : 1920
  
  Image Height                    : 1080
  
  Graphics Mode                   : srcCopy
  
  Op Color                        : 0 0 0
  
  Compressor ID                   : avc1
  
  Source Image Width              : 1920
  
  Source Image Height             : 1080
  
  X Resolution                    : 72
  
  Y Resolution                    : 72
  
  Compressor Name                 : GoPro AVC encoder
  
  Bit Depth                       : 24
  
  Color Representation            : nclx 1 1 1
  
  Video Frame Rate                : 59.94
  
  Time Code                       : 3
  
  Balance                         : 0
  
  Audio Format                    : mp4a
  
  Audio Channels                  : 2
  
  Audio Bits Per Sample           : 16
  
  Audio Sample Rate               : 48000
  
  Text Font                       : Unknown (21)
  
  Text Face                       : Plain
  
  Text Size                       : 10
  
  Text Color                      : 0 0 0
  
  Background Color                : 65535 65535 65535
  
  Font Name                       : Helvetica
  
  Other Format                    : tmcd
  
  Warning                         : [minor] The ExtractEmbedded option may find more tags in the movie data
  
  Matrix Structure                : 1 0 0 0 1 0 0 0 1
  
  Media Header Version            : 0
  
  Media Create Date               : 2018:04:12 14:38:32
  
  Media Modify Date               : 2018:04:12 14:38:32
  
  Media Time Scale                : 60000
  
  Media Duration                  : 0:17:42
  
  Handler Class                   : Media Handler
  
  Handler Type                    : NRT Metadata
  
  Handler Description             : GoPro SOS
  
  Gen Media Version               : 0
  
  Gen Flags                       : 0 0 0
  
  Gen Graphics Mode               : srcCopy
  
  Gen Op Color                    : 0 0 0
  
  Gen Balance                     : 0
  
  Meta Format                     : fdsc
  
  Image Size                      : 1920x1080
  
  Megapixels                      : 2.1
  
  Avg Bitrate                     : 30.1 Mbps
  
  Rotation                        : 0

  Part 2
  There is a pretty obvious "stutter" at the 17:42 mark where the two clips are combined. I’ve tried using ffmpeg and iMovie, but both give the same results. The GoPro broke up the event into multiple clips on it’s own so it seems weird that there would be any information missing. Is there any way to get rid of this stutter ?

  Thanks !

• Standardized "Skip Intro" in MP4 video files ?

  25 mai 2020, par Crissov

  Is there a standardized way to mark up specific parts of a MP4-contained video as skippable, e.g. trailers, recaps, intros/outros, opening/closing credits, in the metadata in the file itself ? If possible, I would like to set this with FFmpeg or MP4box.

  



  I know that the mvhd box in MOV files makes it possible to specify a single preview. 
I assume Netflix and the like use specially named or hinted chapters, either from file-internal metadata or from a central database, to provide this feature. 
I want to add this now to videos in my personal library, just in case Kodi, VLC or other players and media centers add support for this feature.

  



  Edit List Box elst

  



  As mentioned in the first comment, Edit Lists may be a solution. They are specified in section 8.6.6 of ISO/IEC 14496-12:2015 (ISOBMFF), which I partially cite below.

  



  moov > trak+ > edts ? > elst*

  



  


  [elst] contains an explicit time-line map. 
 Each entry defines part of the track time-line :
  
 by mapping part of the media time-line,
  
 or by indicating ‘empty’ time,
  
 or by defining a ‘dwell’, where a single time-point in the media is held for a period.

  
 


  

  • version is an integer that specifies the version of this box (0 or 1)

  


  • entry_count is an integer that gives the number of entries in the following table

  


  • segment_duration is an integer that specifies the duration of this edit segment in units of the timescale in the Movie Header Box

  


  • media_time is an integer containing the starting time within the media of this edit segment (in media time scale units, in composition time). If this field is set to –1, it is an empty edit. The last edit in a track shall never be an empty edit. Any difference between the duration in the Movie Header Box, and the track’s duration is expressed as an implicit empty edit at the end.

  


  • media_rate specifies the relative rate at which to play the media corresponding to this edit segment. If this value is 0, then the edit is specifying a ‘dwell’ : the media at media-time is presented for the segment-duration. Otherwise this field shall contain the value 1.

  


  


  


• FFMPEG : cut clips from a long video with "fast seek" while maintaining accuracy

  15 août 2020, par japseow

  I have this 3 hour long video which consists of <1-5 seconds of black frames> — < clip > — <1-5 seconds of black frames> — < clip > — ...

  &#xA;

  I could successfully get the clip without the black frames with the slow seek, but it takes over 4 minutes just for seeking.

  &#xA;

  ffmpeg -y -i "C:\Users\user\Videos\obs\part1.mp4" -ss 4370.48 -to 4384.95 -c:a copy -c:v hevc_nvenc -rc vbr_hq -cq 19 -b:v 10000k -maxrate:v 12500k "C:\Users\user\Videos\obs\____delete1.mp4"

  &#xA;

  I tried using the fast seek which takes only 4 sec, but it includes a 4 sec blackframe chunk at the end of the video. The output that should've been 14 sec long became 18 sec.

  &#xA;

  ffmpeg -y -ss 4370.48 -i "C:\Users\user\Videos\obs\part1.mp4" -to 14.47 -c:a copy -c:v hevc_nvenc -rc vbr_hq -cq 19 -b:v 10000k -maxrate:v 12500k "C:\Users\user\Videos\obs\____delete2.mp4"

  &#xA;

  My video has around 640 clips so it's impractical to wait that long just for seeking, and it'll only get worse when I'll be seeking at around the 2+ hour mark.

  &#xA;