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• 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.

  


  


  


• Building FFmpeg for use in Swift

  7 juillet 2021, par NCrusher

  With the new XCode/Swift release comes the ability to use binary dependencies. This seems to me to be an ideal time to create an SPM package for FFMpeg.

  


  However, while I've spent the last year learning to code i Swift, I'm actually not all that familiar with how to build libraries, especially those as complex as FFmpeg with all the configurable libraries and third-party dependencies.

  


  There's kewlbear's iOS build scripts, but these are for iOS/tvOS and ideally an FFMpeg SPM package would be usable for MacOS also. It's also not updated for the newest Xcode and Swift versions.

  


  My personal interest is simply in audio and I don't need a lot of bells and whistles, but I figure the ideal situation would be a full package with the entire source and whatever dependencies it needs, and then when it's used as a package dependency, the compiler will just use the parts it needs.

  


  I guess my question is...how would I ideally compile the ffmpeg code for this purpose. I'm trying to follow the directions for compiling yourself, but I'm stuck at the point of compiling gettext because I'm not sure if I should follow the directions (in the gettext source code) for compiling a fat binary for multiple architectures, and when I try to run :

  


        ./configure CC="gcc -arch i386 -arch x86_64 -arch ppc -arch ppc64" \
                  CXX="g++ -arch i386 -arch x86_64 -arch ppc -arch ppc64" \
                  CPP="gcc -E" CXXCPP="g++ -E"



  


  I get the following error :

  


   checking whether the C compiler works... no configure: error: in
 `/Users/nolainecrusher/Downloads/FFMpeg-source/gettext-0.21/gettext-runtime':
 configure: error: C compiler cannot create executables See
 `config.log' for more details configure: error: ./configure failed for
 gettext-runtime


  


  and config.log doesn't really tell me anything useful :

  


  This is what I see at the end of the log :

  


   mkdir_p='$(MKDIR_P)' oldincludedir='/usr/include' pdfdir='${docdir}'
 prefix='/usr/local' program_transform_name='s,x,x,' psdir='${docdir}'
 sbindir='${exec_prefix}/sbin' sharedstatedir='${prefix}/com' subdirs='
 gettext-runtime libtextstyle gettext-tools' sysconfdir='${prefix}/etc'
 target_alias=''


  


  I feel like maybe I'm going about this the wrong way, but I'm not sure what the right way is.

  


• Auto-Transcode/Compress .mkv to .mp4 on Qnap TS-251+

  9 novembre 2020, par DarkDiamond

  I rip my DVDs with MakeMKV in order to be able to watch them on my TV, as I do not have a DVD-player that supports any output connector that fit into my TV as the TV is relatively new whereas the DVD-player is quite old. (As I only use the rips for my personal entertainment and do not share them there is absolutely no copyright problem).

  


  The problem with the output files is the extreme size as they are the raw data from the disk. Now I would like these files to be compressed into a .mp4 file as soon as they are finished. The problem is that the file is created before everything is in it, so I probably need to write it into a local drive and copy it to its destination later. Then I will copy them to my Qnap NAS TS-251+.

  


  There I want it do be compressed into a much smaller .mp4 file (usually the .mp4s are a sixth of the original size). I found something using ffmpeg, so I just need a script that does this for me. I do not mind to use a Docker machine for it, but I do not know how to do it. I found this :

  


  ffmpeg -i input.mkv -c:v -crf 18 -preset veryslow -c:a copy out.mp4 here.

  


  I also found this video, so I know it is in theory possible, I just do not know how to realise it.

  


  In case you ask why I want to use the Qnap NAS, it allows hardware acceleration, whereas my laptop does not.