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• Merge 3 ffmpeg audio tracks into one file without normalized audio

  29 juillet 2022, par Meh.

  I'm trying to essentially get the command line version of dropping files into Audacity, where they all start at the same time and when I export it, it will export as one file.

  


  I'm using this command ffmpeg -i <file> -i <file> -i <file> -filter_complex amix=inputs=3 <out></out></file></file></file> from another question and it makes the audio/end product softer. I can definitely tell a difference without any checking. I am working with files from the musdb18 database so I can make instrumentals manually for a project.

  


  How can I combine multiple audio files without ffmpeg doing something weird like changing the db or normalizing the audio ?

  


• 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 ?

  


• Anomalie #2133 (Nouveau) : Statut des messages de forum et statuts des documents joints

  18 juin 2011, par guytarr °

  Lorsque l’on est en modération à posteriori (ou probablement tous les cas de figures où un message de forum n’est pas publie immediatement), le(s) document(s) joint(s) à un message de forum ne passe pas en "publie" au moment où le message est (...)