Recherche avancée

Sur d’autres sites (11264)

• libavcodec/libx264 : fix reference frame computation based on level

  16 avril 2020, par Josh Brewster

  libavcodec/libx264 : fix reference frame computation based on level
  The current implementation allows passing levels to libavcodec as
  
  integers (such as "31" instead of "3.1").
  However, in this case, the maximum reference frame value per level was
  
  ignored because libavcodec converted the string to 310 instead of 31.
  Since libx264 has correctly parsed the level to int
  
  (x4->params.i_level_idc), we should rely on this value instead of
  
  attempting to parse the level string on our own.
  Signed-off-by : Josh Brewster <josh.brewster@protonmail.com>
  
  Signed-off-by : Josh de Kock <josh@itanimul.li>
  

  • [DH] libavcodec/libx264.c

• avformat/matroskaenc : Move adding SeekEntry into end_ebml_master_crc32()

  27 avril 2020, par Andreas Rheinhardt

  avformat/matroskaenc : Move adding SeekEntry into end_ebml_master_crc32()
  Up until now, SeekEntries were already added before
  
  start_ebml_master_crc32() was even called and before we were actually
  
  sure that we really write the element the SeekHead references : After
  
  all, we might also error out later ; and given that the allocations
  
  implicit in dynamic buffers should be checked, end_ebml_master_crc32()
  
  will eventually have to return errors itself, so that it is the right
  
  place to add SeekHead entries.
  The earlier behaviour is of course a remnant of the time in which
  
  start_ebml_master_crc32() really did output something, so that the
  
  position before start_ebml_master_crc32() needed to be recorded.
  
  Erroring out later is also not as dangerous as it seems because in
  
  this case no SeekHead will be written (if it happened when writing
  
  the header, the whole muxing process would abort ; if it happened
  
  when writing the trailer (when writing chapters not available initially),
  
  writing the trailer would be aborted and no SeekHead containing the
  
  bogus chapter entry would be written).
  This commit does not change the way the SeekEntries are added for those
  
  elements that are output preliminarily ; this is so because the SeekHead
  
  is written before those elements are finally output and doing it
  
  otherwise would increase the amount of seeks.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/matroskaenc.c

• 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.