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• Unknown Decoder in ffmpeg

  17 mars 2020, par user6782547

  I have a script, that is called from Plex after the recording of a movie. This script just crops the black borders of the movie.

  When I call it directly from the command line, it works flawlessly. But when Plex calls it, it says : "Unknown decoder", even if I call it with the key word "auto" for the decoder.

  There’s another problem, that might give a hint to solve my problem. It also says : "WARNING: library configuration mismatch". (Only when being called from Plex.) This is probably, because I compile ffmpeg from the Debian source package (so that I can add the whole CUDA functionality).
  I had a look at the dynamic linker path, but it is empty on the command line.

  What is so different, when this command is called from Plex, than when I call it manually from the command line ?

  Thanks for any help

• How to save ffmpeg segmets to disk immediately with sub-second intervals ?

  20 octobre 2023, par amfast

  I'm trying to record video on a raspberry and have it save as much as possible (sub-second resolution) in case of a power cutoff.

  


  I use -f segment to save the encoded stream in 100ms segments with the hope that all but the interrupted (by power cutoff) segment will be saved in memory. Unfortunately, when cutting off power, all the destination files (output_0001.mp4, output_0002.mp4, ...) are created, but empty.

  


  To save the files to disk immediately, I added the -strftime 1 option that allows formatting the output filename as time. It seems weird that this is the (only ?) way to trigger immediate saving of files, but it works - untill I try to have segments smaller than 1 second. The problem seems to be that the format string %d, that previously added a sequence number in my output filenames, now represents "day" (i.e. date) and the smallest resolution time format string is %S for second. I saw %f suggested somewhere for smaller resolutions, but it only prints "%f".

  


  The result is that the segmentation part of ffmpeg does create 100ms segments and save them to disk immediately, but the strftime feature gives the output files names that only change every second, so all the interim files are overwritten.

  


  Example of the failing command below. Without the -strftime option this creates nice segments, but does not save them to disk immediately.

  


  libcamera-vid --flush \
    --framerate ${FRAMERATE} \
    --width ${WIDTH} \
    --height ${HEIGHT} \
    -n \
    -t ${TIMEOUT} \
    --codec yuv420 \
    -o - | 
ffmpeg \
    -fflags nobuffer \
    -strict experimental \
    -loglevel debug \
    -flags low_delay \
    -f rawvideo \
    -pix_fmt yuv420p \
    -s:v ${WIDTH}x${HEIGHT} \
    -r ${FRAMERATE} \
    -i - \
    -c:v h264_v4l2m2m \
    -f segment \
    -segment_time 0.1 \
    -segment_format mp4 \
    -reset_timestamps 1 \
    -strftime 1 \
    -b:v ${ENCODING_BITRATE} \
    -g 1 \
    "output_%04d.mp4"


  


  Question :
  
Is there another way besides -strftime to trigger immediate saving ? Or is there a mechanism to feed finer resolution format strings to the output filename ?

  


• bash loop through list of file paths - characters get removed when sending to ffmpeg [duplicate]

  9 octobre 2018, par Brad Johnson

  This question already has an answer here :

  • Bash while loop stops for no reason ?
    
    1 answer
    

  I have a text file that contains a list of paths to flac files I want to convert to wav. Here is a small section of it :

  /mnt/nfs/Music/Rob D/1995 - Clubbed To Death/Rob D - 02 - Clubbed To Death _Kurayamino Variation_.flac
  
  /mnt/nfs/Music/Blonde Redhead/2000 - Melody of Certain Damaged Lemons/11 - For the Damaged Coda.flac
  
  /mnt/nfs/Music/I Monster/2001 - Daydream In Blue/01 - Daydream In Blue.flac
  
  /mnt/nfs/Music/Moby/2002 - Extreme Ways/01 - Extreme Ways.flac
  
  /mnt/nfs/Music/RJD2/2002 - Deadringer/01 - The Horror.flac
  
  /mnt/nfs/Music/RJD2/2002 - Deadringer/03 - Smoke & Mirrors.flac
  
  /mnt/nfs/Music/RJD2/2002 - Deadringer/06 - Ghostwriter.flac
  
  /mnt/nfs/Music/RJD2/2002 - Deadringer/10 - Chicken-Bone Circuit.flac
  
  /mnt/nfs/Music/FC Kahuna/2003 - Hayling/01 - Hayling _Original_.flac
  
  /mnt/nfs/Music/Lamb/2003 - Between Darkness and Wonder/04 - Angelica.flac

  I’m trying to loop through it like so :

  while read -r line; do
  
   wavfile=$(basename "$line")
  
   wavfile="${wavfile%.*}"
  
   ffmpeg -i "$line" "$2/$wavfile.wav"
  
  done <$1

  ...where $1 is where I would pass the name of the text file and $2 is the destination directory.

  Here is the output with the irrelevant ffmpeg junk pruned out :

  Input #0, flac, from '/mnt/nfs/Music/Rob D/1995 - Clubbed To Death/Rob D - 02 - Clubbed To Death _Kurayamino Variation_.flac':
  
  ...
  
  Output #0, wav, to '/mnt/gray/Clubbed To Death/Rob D - 02 - Clubbed To Death _Kurayamino Variation_.wav':
  
  ...
  
  /nfs/Music/Blonde Redhead/2000 - Melody of Certain Damaged Lemons/11 - For the Damaged Coda.flac: No such file or directory
  
  ...
  
  Input #0, flac, from '/mnt/nfs/Music/I Monster/2001 - Daydream In Blue/01 - Daydream In Blue.flac':
  
  ...
  
  Output #0, wav, to '/mnt/gray/Clubbed To Death/01 - Daydream In Blue.wav':
  
  ...
  
  nt/nfs/Music/Moby/2002 - Extreme Ways/01 - Extreme Ways.flac: No such file or directory
  
  ...
  
  Input #0, flac, from '/mnt/nfs/Music/RJD2/2002 - Deadringer/01 - The Horror.flac':
  
  ...
  
  Output #0, wav, to '/mnt/gray/Clubbed To Death/01 - The Horror.wav':
  
  ...
  
  nt/nfs/Music/RJD2/2002 - Deadringer/03 - Smoke & Mirrors.flac: No such file or directory
  
  ...
  
  Input #0, flac, from '/mnt/nfs/Music/RJD2/2002 - Deadringer/06 - Ghostwriter.flac':
  
  ...
  
  Output #0, wav, to '/mnt/gray/Clubbed To Death/06 - Ghostwriter.wav':
  
  ...
  
  nt/nfs/Music/RJD2/2002 - Deadringer/10 - Chicken-Bone Circuit.flac: No such file or directory
  
  ...
  
  Input #0, flac, from '/mnt/nfs/Music/FC Kahuna/2003 - Hayling/01 - Hayling _Original_.flac':
  
  ...
  
  Output #0, wav, to '/mnt/gray/Clubbed To Death/01 - Hayling _Original_.wav':
  
  ...
  
  /nfs/Music/Lamb/2003 - Between Darkness and Wonder/04 - Angelica.flac: No such file or directory

  If you pay attention to the paths that ffmpeg reports don’t exist, you’ll see that a seemingly random number of characters has been removed from the beginning. This appears to happen on even numbered lines, but odd numbered lines work. I can only reproduce this behavior when using ffmpeg. If I replace the ffmpeg line with a simple echo statement, every file path is shown to be correct. How can this be ?

  Other suggestions of accomplishing this are also welcome, however I do need the files processed in the order by which I have them listed in the file.