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• avformat/segafilmenc : Remove redundant checks

  14 janvier 2020, par Andreas Rheinhardt

  avformat/segafilmenc : Remove redundant checks
  If an audio stream is present, the Sega FILM muxer checks for its
  
  compability with the container during init, so that the very same check
  
  needn't be repeated during writing the trailer.
  Essentially the same is true for the presence of a video stream : It has
  
  already been checked during init. Furthermore, after the check for the
  
  presence of a video stream succeeded, a pointer is set to point to the
  
  video stream. Yet said pointer (which was NULL before) will be
  
  derefenced anyway regardless of the result of the check. Coverity thus
  
  complained about this in CID 1434155 and removing this pointless check
  
  will also fix this issue.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/segafilmenc.c

• FFMPEG Dash with tiles of thumbnail images

  31 juillet 2020, par martyn Gilbert

  As of DASH-IF IOP version 4.2, section 6.2.6 defines the notion of image-based tracks in DASH :
https://dashif.org/docs/DASH-IF-IOP-v4.3.pdf.

  



  This is the ability to have an adaption set made up of mime type images that themselves are a strip of low resolution thumbnails. 
A player will use these thumbnails when the user hovers their mouse over the video timeline and get a 
preview of the the frame at that approximate timecode.

  



  Theo player website has a page dedicated to this function for playback :
https://www.theoplayer.com/blog/in-stream-thumbnail-support-dvr-dash-streams

  



  I need to generate a dash stream (not live) using ffmpeg that also contains these thumbnails. 
I already have an ffmpeg command that will generate the film strip of jpgs which outputs a thumbnail every 5 seconds of input video and joins 5 of these together in a single jpg :

  



  ffmpeg -i INPUT -q:v 20 -vf "select=not(mod(n\,125)),scale=480:270,tile=5x1" -vsync vfr output%d.jpg

  



  and the mpeg dash itself :

  



  ffmpeg -i INPUT -y -map 0 -acodec aac -ac 2 -ar 48000 -s 960x540 -vcodec libx264 -f dash -preset veryfast -b:v:2 1500k -seg_duration 2 output.mpd

  



  But I cannot find a way in ffmpeg to include the thumbnails in the dash mpd file.

  


• Converting Quicktime (.mov ) from iPhone to mp4

  24 mars 2020, par user3094755

  On iPhones running iOS 11, if a video is pre-recorded and uploaded I get the following errors :- ( ie, the video is recoded on the iPhone and then uploaded as an attachment ).

  $ ./ffmpeg -i .mov -vcodec h264 -acodec mp4 test-output.mp4
  
  FFmpeg version CVS, Copyright (c) 2000-2004 Fabrice Bellard
  
  Mac OSX universal build for ffmpegX
  
    configuration:  --enable-memalign-hack --enable-mp3lame --enable-gpl --disable-vhook --disable-ffplay --disable-ffserver --enable-a52 --enable-xvid --enable-faac --enable-faad --enable-amr_nb --enable-amr_wb --enable-pthreads --enable-x264 
  
    libavutil version: 49.0.0
  
    libavcodec version: 51.9.0
  
    libavformat version: 50.4.0
  
    built on Apr 15 2006 04:58:19, gcc: 4.0.1 (Apple Computer, Inc. build 5250)
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x5597b8]mov: header not found !!! (err:0, moov:0, mdat:0) pos:3189455560
  
  .mov: Error while opening file
  
  $

  If the video is recorded and then transferred to a Desktop uploaded and then converted it works OK.

  If I use a ‘live’ recording then all is OK.

  I found this…

  https://www.howtogeek.com/327689/how-to-make-your-iphone-use-jpg-and-mp4-files-instead-of-heif-and-hevc/

  Which seems to suggest iOS 11 will use different formats, but this appears to make no difference whatever the settings are for ‘High Efficiency / Most Compatible’.

  Any ideas ?