Recherche avancée

Sur d’autres sites (3229)

• Write Live Photo metadata to video using FFMPEG

  13 août 2021, par Luke Burns

  According to Apple Live Photo file format, there are three pieces of metadata that need to be written for a JPEG and MOV to be accepted as a live photo. I can use exiftool and ffmpeg to write the necessary content identifier metadata.

  


  For the JPEG :

  


  exiftool -TagsFromFile reference.jpeg -makernotes -ContentIdentifier image.jpeg
exiftool -ContentIdentifier="$id" image.jpeg


  


  Similarly, ffmpeg can be used to write the top-level Quicktime metadata with matching id.

  


  However I'm having trouble with the timed metadata : ["com.apple.quicktime.still-image-time" : 0xFF].

  


  I can't even manage to produce a copy of an existing live photo MOV file using ffmpeg that preserves the necessary timed metadata.

  


  ffmpeg -i original.mov -map 0 -c copy -movflags use_metadata_tags copy.mov


  


  copies the global metadata (i.e. com.apple.quicktime.content.identifier), but loses the necessary still-image-time which can be confirmed using exiftool :

  


  > exiftool -G -U -ee original.mov | grep 'Still Image Time'
[QuickTime]     Still Image Time                : -1
> exiftool -G -U -ee copy.mov | grep 'Still Image Time'
> 


  


  How can I write the timed metadata using ffmpeg—specifically the still-image-time data ?

  


  Edit : it looks like this may be happening because ffmpeg does not know how to handle the mebx tag on data streams :

  


  [mov @ 0x7fb232091400] Unknown hldr_type for mebx, writing dummy values


  


  And ffmpeg doesn't seem to have a way to copy unknown streams. This appears to also be a problem for dealing with the fdsc tag in GoPro metadata streams (e.g. see https://gist.github.com/radimklaska/8974637522a751adb49db0de3be482c9#file-gopro_hevc_to_dnxhd-sh-L125), so it's often copied over as gpmd data, which ensures it's not overwritten with dummy values, but this trick doesn't work in the case of live photos mebx metadata.

  


• Write timed Live Photo metadata to video using FFMPEG

  20 décembre 2020, par Luke Burns

  According to Apple Live Photo file format, there are three pieces of metadata that need to be written for a JPEG and MOV to be accepted as a live photo. I can use exiftool and ffmpeg to write the necessary content identifier metadata, but I'm having trouble with the timed metadata : ["com.apple.quicktime.still-image-time" : 0xFF].

  


  I can't even manage to produce a copy of an existing live photo MOV file using ffmpeg that preserves the necessary timed metadata.

  


  ffmpeg -i original.mov -map 0 -c copy -movflags use_metadata_tags copy.mov


  


  copies the global metadata (i.e. com.apple.quicktime.content.identifier), but loses the necessary still-image-time which can be confirmed using exiftool :

  


  > exiftool -G -U -ee original.mov | grep 'Still Image Time'
[QuickTime]     Still Image Time                : -1
> exiftool -G -U -ee copy.mov | grep 'Still Image Time'
> 


  


  How can I write the timed metadata using ffmpeg—specifically the still-image-time data ?

  


• avformat/asfdec_o : Don't segfault with lots of attached pics

  12 novembre 2020, par Andreas Rheinhardt

  avformat/asfdec_o : Don't segfault with lots of attached pics
  The ASF file format has a limit of 127 streams and the "asf_o" demuxer
  
  (the ASF demuxer from Libav) has an array of pointers for a structure
  
  called ASFStream that is allocated on demand for every stream. Attached
  
  pictures are not streams in the sense of the ASF specification, yet the
  
  demuxer created an ASFStream for them ; and in one codepath it also
  
  forgot to check whether the array of ASFStreams is already full. The
  
  result is a write beyond the end of the array and a segfault lateron.
  Fixing this is easy : Don't create ASFStreams for attached picture
  
  streams.
  (Other results of the current state of affairs are unnecessary allocations
  
  (of ASFStreams structures), the misparsing of valid files (there might not
  
  be enough ASFStreams left for the valid streams if attached pictures take
  
  up too many) ; furthermore, the ASFStreams created for attached pictures all
  
  have the stream number 0, an invalid stream number (the valid range is
  
  1-127). This means that invalid data (packets for a stream with stream
  
  number 0) won't get rejected lateron.)
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/asfdec_o.c