Recherche avancée

Sur d’autres sites (7689)

• 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.

  


  


  


• How to mix multiple audios from the end ?

  24 avril 2020, par Vijay Singh Kholiya

  In my project I have a feature of recording the meeting which is in a form of group discussion consisting of multiple attendees. All attendees will be having their own personal system and they will be accessing that web app through their personal account. Their is one meeting controller(only one person) who starts the recording and for every attendee whether he is present in the same room or is remote, their microphone will be opened and recording will be stored in S3 bucket.

  



  Since I need a single audio file which consists of the whole meeting recording, so I am using SOX for this. But the problem is, what if any attendee attends meeting in between the discussion so he's audio recording length will be smaller than everyone else.

  



  Since I am mixing the audio files to get one file, but for this late commer attendee the mixing will be wrong. So how can I mix the audios from the end instead of starting ?

  


• Different results between windows and Linux in opencv c++

  24 mars 2020, par Samer

  I have tried this opencv and ffmpeg C++ code to demux a video and edit it and mux it back again but it doesn’t seem to work properly on windows (using Visual Studio)

  the problem occurs by skipping some frames especially at the end of the video and increasing the video output size not on all windows PCs. We have tried it on a 35 MB video and when we did the editing the output video size was 2.8GB on some windows PCs and the last frames skipped (the problem) and some other PCs the output video size was 500MB and there were no skipped frames (all fine).

  so the question is, why would the same code with the same build and windows versions behave differently and produce problems on some Pcs ?

  (we also did it on linux ubuntu and macos and it was working fine on different PCs)

  https://github.com/WajdiMuh/parallelalgo for the files

  https://gjuedujo-my.sharepoint.com/personal/m_albizreh1_gju_edu_jo/_layouts/15/onedrive.aspx?id=%2Fpersonal%2Fm%5Falbizreh1%5Fgju%5Fedu%5Fjo%2FDocuments%2FParallel%20Project%2Fbinr&originalPath=aHR0cHM6Ly9nanVlZHVqby1teS5zaGFyZXBvaW50LmNvbS86ZjovZy9wZXJzb25hbC9tX2FsYml6cmVoMV9nanVfZWR1X2pvL0VzaHFWNDJCVThkQ25KOFV0dm82NHJNQmdoOWdCeEZOblkwQWtRMkQ0MU5UV3c_cnRpbWU9TTl4Zi1YblAxMGc for the release version (vidd.MP4 is the video)

  Thanks in Advance