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• avutil : add alias names for gray 8/16 colour spaces

  23 juillet 2014, par Vittorio Giovara

  avutil : add alias names for gray 8/16 colour spaces
  

  • [DBH] libavutil/pixdesc.c

• Preserving original colour spaces with FFmpeg

  12 décembre 2022, par Hashim Aziz

  I'm trying to implement some logic in my FFmpeg scripts to make sure that a video's colourspace is always preserved when upscaling. Just setting the metadata seems to be enough to do this, but the hard part is figuring out which metadata is needed, especially when the colourspace and related colour data reads as unknown, as is so often the case with many of my source videos.

  


  As I understand it, two things determine a video's original colourspace : whether a video is standard or high definition, and if it's standard definition, whether it's NTSC or PAL/SECAM. Based on this, I came up with the following logic to check the height of a video and set colourspace according to it :

  


  height=$(ffprobe -v error -select_streams v:0 -show_entries stream=width -of default=nw=1:nk=1 "$1" | tr -d $'\r')
colour_space=$(ffprobe -v error -select_streams v:0 -show_entries stream=color_space -of default=nw=1:nk=1 "$1" | tr -d $'\r')

# If input is standard definition and colourspace is BT601 (NTSC)
if [[ $height -lt 720 && $colour_space == "smpte170m" ]]; then 
colour_metadata="-colorspace smpte170m -color_trc smpte170m -color_primaries smpte170m" # set metadata to BT601 (NTSC)
# If input is standard definition and colourspace is BT601 (PAL and SECAM) or unknown
elif [[ $height -lt 720 && ($colour_space == "bt470bg" || $colour_space == "unknown") ]]; then 
colour_metadata="-colorspace bt470bg -color_trc gamma28 -color_primaries bt470bg" # set metadata to superior/more common PAL/SECAM
elif [[ $height -ge 720 ]]; then # If input is high definition
colour_metadata="-colorspace bt709 -color_trc bt709 -color_primaries bt709" # set metadata to BT.709
else echo "Unrecognised colorspace $color_space detected, leaving colour untouched"
fi


  


  Is this approach likely to work for the majority of videos ? Is there anything wrong with it that can be improved, or is it completely flawed for some reason that I'm missing ?

  


• avcodec/h2645_sei : validate Mastering Display Colour Volume SEI values

  13 avril 2024, par Kacper Michajłow

  avcodec/h2645_sei : validate Mastering Display Colour Volume SEI values
  As we can read in ST 2086 :
  Values outside the specified ranges of luminance and chromaticity values
  
  are not reserved by SMPTE, and can be used for purposes outside the
  
  scope of this standard.
  This is further acknowledged by ITU-T H.264 and ITU-T H.265. Which says
  
  that values out of range are unknown or unspecified or specified by
  
  other means not specified in this Specification.
  Signed-off-by : Kacper Michajłow <kasper93@gmail.com>
  
  Signed-off-by : Niklas Haas <git@haasn.dev>
  

  • [DH] libavcodec/h2645_sei.c