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• How can I remove every nth frame from raw video using ffmpeg ?

  15 juin 2024, par DaveB44

  Question moved to SuperUser, please reply there

  


  I have many cine films that have been digitally converted. They have been converted as a 25 fps with 2 frames in every 23 duplicated. I need to remove the duplicated frames using a bitstream filter so there is no decoding/encoding.

  


  After removing the frames I will change to the original cine frame rate of 18 fps. I will then change the frame rate to 25 fps using duplicated frames. I don't want to interpolate as I want to preserve the jerky format of the cine. Finally I will video editing software that will do the final encoding.

  


  All the additional steps will cause several stages of decoding/encoding, that I need to avoid.

  


  First I used a combination of the answers to FFmpeg remove video frames at specific intervals and FFmpeg remove every 6th frame starting from the 3rd frame, on an mp4 file to check it works. I modified it to remove every 4th and 17th frame in 25.

  


  ffmpeg -loglevel warning -i cine.mp4 -an -vf "select='if((mod(n-4,25)),(mod(n-17,25)))',setpts='N/FRAME_RATE/TB'" cine-23.mp4


  


  This works fine, but I end up with a file a quarter the size.

  


  I now used Gyan's answer in Using ffmpeg to change framerate to extract the raw bitstream.

  


  ffmpeg -loglevel warning -i cine.mp4 -c copy -f h264 cine.h264


  


  This created the h264 file as expected, surprisingly it was 16 kB smaller than the original (67 GB file size).

  


  I then modified the code to use the .h264 file.

  


  ffmpeg -loglevel warning -i cine.h264 -vf "select='if((mod(n-4,25)),(mod(n-17,25)))',setpts='N/FRAME_RATE/TB'" cine-23.h264


  


  This gave the following error, but created the cine-23.h264 file although it was the same size as cine-23.mp4 in the test above

  


  [h264 @ 00000245ec0bfb80] non-existing SPS 0 referenced in buffering period
    Last message repeated 1 times


  


  I then checked the ffmpeg bitstream filter documentation and found the bitstream filter setts. I changed my code to the following.

  


  ffmpeg -loglevel warning -i cine.h264 -bsf:v "select='if((mod(n-4,25)),(mod(n-17,25)))',setts=pts='N/FRAME_RATE/TB'" cine-23.h264


  


  Which resulted in the following error.

  


  [vost#0:0/libx264 @ 000002916cf173c0] Error parsing bitstream filter sequence 'select='if((mod(n-4,25)),(mod(n-17,25)))',setts=pts='N/FRAME_RATE/TB'': Bitstream filter not found
Error opening output file cine-23.h264.
Error opening output files: Bitstream filter not found


  


  I'm assuming the error is because setts does not support select. Is there another way to achieve what I am looking for ?

  


  I could use mpdecimate but as that has to compare each frame it is much slower than defining it only needs to delete frames 4 and 17 in every second.

  


  This is the output of ffprobe on my original file.

  


  ffprobe version 2023-11-28-git-47e214245b-full_build-www.gyan.dev Copyright (c) 2007-2023 the FFmpeg developers
  built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --pkg-config=pkgconf --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-dxva2 --enable-d3d11va --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      58. 32.100 / 58. 32.100
  libavcodec     60. 35.100 / 60. 35.100
  libavformat    60. 18.100 / 60. 18.100
  libavdevice    60.  4.100 / 60.  4.100
  libavfilter     9. 14.100 /  9. 14.100
  libswscale      7.  6.100 /  7.  6.100
  libswresample   4. 13.100 /  4. 13.100
  libpostproc    57.  4.100 / 57.  4.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'cine.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 19529864
    compatible_brands: mp42isom
    creation_time   : 2024-02-19T21:01:10.000000Z
  Duration: 00:01:00.00, start: 0.000000, bitrate: 9245 kb/s
  Stream #0:0[0x1](eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 720x576 [SAR 35:32 DAR 175:128], 9243 kb/s, 25 fps, 25 tbr, 25 tbn (default)
    Metadata:
      creation_time   : 2024-02-19T21:01:10.000000Z
      handler_name    : Video Media Handler
      vendor_id       : [0][0][0][0]
      encoder         : AVC Coding


  


• What is the best way to split videos into equally sized parts using ffmpeg ? [closed]

  18 juin 2024, par GBPU

  I have tried to split an mp4 file into smaller parts of equal time length like this ffmpeg -i ../data/2024-06-02_12-34-51.mp4 -c copy -map 0 -segment_time 00:00:05 -f segment v1_%03d.mp4. However, this produced videos of highly variables size, some 25x larger than others. I assume this was due to inconsistent framerate during recording.

  


  Next, I tried a script that would split based and limit each part to a specific size :

  


  #!/bin/sh
# Short script to split videos by filesize using ffmpeg by LukeLR

if [ $# -ne 3 ]; then
    echo 'Illegal number of parameters. Needs 3 parameters:'
    echo 'Usage:'
    echo './split-video.sh FILE SIZELIMIT "FFMPEG_ARGS'
    echo 
    echo 'Parameters:'
    echo '    - FILE:        Name of the video file to split'
    echo '    - SIZELIMIT:   Maximum file size of each part (in bytes)'
    echo '    - FFMPEG_ARGS: Additional arguments to pass to each ffmpeg-call'
    echo '                   (video format and quality options etc.)'
    exit 1
fi

FILE="../data/$1"
SIZELIMIT="$2"
FFMPEG_ARGS="$3"

# Duration of the source video
DURATION=$(ffprobe -i "$FILE" -show_entries format=duration -v quiet -of default=noprint_wrappers=1:nokey=1|cut -d. -f -2)

# Duration that has been encoded so far
CURDURATION=0

# Filename of the source video (without extension)
BASENAME="${FILE%.*}"

# Extension for the video parts
#EXTENSION="${FILE##*.}"
EXTENSION="mp4"

# Number of the current video part
i=1

# Filename of the next video part
NEXTFILENAME="$BASENAME-$i.$EXTENSION"

echo "Duration of source video: $DURATION"

# Until the duration of all partial videos has reached the duration of the source video
#while [[ $CUR_DURATION -lt $DURATION ]]; do
while [[ $(bc <<< "$CURDURATION < $DURATION") -eq 1 ]]; do
    # Encode next part
    echo ffmpeg -i "$FILE" -ss "$CURDURATION" -fs "$SIZELIMIT" $FFMPEG_ARGS "$NEXTFILENAME"
    ffmpeg -ss "$CURDURATION" -i "$FILE" -fs "$SIZELIMIT" $FFMPEG_ARGS "$NEXTFILENAME"

    # Duration of the new part
    NEWDURATION=$(ffprobe -i "$NEXTFILENAME" -show_entries format=duration -v quiet -of default=noprint_wrappers=1:nokey=1|cut -d. -f -2)

    # Total duration encoded so far
    echo $CURDURATION
    CURDURATION=$(bc <<< "$CURDURATION + $NEWDURATION")
    echo $CURDURATION

    i=$((i + 1))

    echo "Duration of $NEXTFILENAME: $NEWDURATION"
    echo "Part No. $i starts at $CURDURATION"
    echo "Current Duration: $CURDURATION"

    NEXTFILENAME="$BASENAME-$i.$EXTENSION"
done


  


  I call the script like this : bash split-video.sh 2024-06-02_12-34-51.mp4 10000000 "-c copy"
Unfortunately, this has an issue where some of the sub videos are extremely short and have wildly inconsistent numbers of frames in them (some with nearly 400, others with 1), despite being similar sizes. I am guessing this has something to do with inconsistent framerate and keyframes or something ?

  


  I am curious what the best way to split a video into equally sized parts, and ideally with similar numbers of frames, is using ffmpeg.

  


• ffmpeg : getting larger gif file after optimization [closed]

  28 août 2024, par xaxa

  I'm trying to use ffmpeg to reduce the size of GIF images by lowering fps and color palette size. This is the command I use :

  


  ffmpeg -i initial.gif -filter_complex "[0]fps=${fps},split[m][t];[t]palettegen=max_colors=${max_colors}[p];[m][p]paletteuse" output.gif


  


  however, for some reason I'm getting larger files even if I do something as stupid as fps=1, max_colors=4.

  


  here's the initial file :


  


  here's what I've got after the transformation :


  


  the command was :

  


  ffmpeg -i eglite.gif -filter_complex "[0]fps=1,split[m][t];[t]palettegen=max_colors=4[p];[m][p]paletteuse" output.gif


  


  and the sizes I get are :

  


  -rw-r--r-- 1 work work    15860 Aug 26 11:30 eglite.gif
-rw-r--r-- 1 work work    21395 Aug 28 21:35 output.gif


  


  Here's my ffmpeg version :

  


  ffmpeg version n7.0.2 Copyright (c) 2000-2024 the FFmpeg developers
built with gcc 14.2.1 (GCC) 20240805
configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-frei0r --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libdav1d --enable-libdrm --enable-libdvdnav --enable-libdvdread --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libharfbuzz --enable-libiec61883 --enable-libjack --enable-libjxl --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libplacebo --enable-libpulse --enable-librav1e --enable-librsvg --enable-librubberband --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpl --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec --enable-nvenc --enable-opencl --enable-opengl --enable-shared --enable-vapoursynth --enable-version3 --enable-vulkan
libavutil      59.  8.100 / 59.  8.100
libavcodec     61.  3.100 / 61.  3.100
libavformat    61.  1.100 / 61.  1.100
libavdevice    61.  1.100 / 61.  1.100
libavfilter    10.  1.100 / 10.  1.100
libswscale      8.  1.100 /  8.  1.100
libswresample   5.  1.100 /  5.  1.100
libpostproc    58.  1.100 / 58.  1.100