Some code snippets

Updated: 2023-12-31
3 min read

pandoc mardown -> pdf

Create pdf file from .md in multiple folders


brew install basictex

# search for cyrillic fonts
fc-list | grep к\

brew tap homebrew/cask-fonts
brew install --cask font-m-plus
brew tap homebrew/cask-fonts
brew install --cask font-m-plus
brew install --cask font-m-plus-1
brew install --cask font-m-plus-1-code

pandoc --pdf-engine xelatex \
--variable mainfont="M+ 1p" --variable sansfont="M+ 1p" --variable monofont="M+ 1m" \
-V geometry:"top=1cm, bottom=2cm, left=1cm, right=1cm" \
--file-scope \
--highlight-style=tango \
-s \
--toc-depth=1 \
--variable=toc-title:" " \
--top-level-division=chapter \
--standalone \
--self-contained \
--from=markdown \
 $(find . -name '*') \
-o book.pdf

Convert all video to audio with ffmpeg in current directory


# Check if ffmpeg is installed
command -v ffmpeg >/dev/null 2>&1 || { echo >&2 "ffmpeg is required but not installed. Aborting."; exit 1; }

# Get a list of all video files in the current directory

# Check if there are any video files in the current directory
if [ ${#video_files[@]} -eq 0 ]
    echo "No video files found in the current directory."
    exit 1

# Loop through all video files and convert them to audio files
for video_file in "${video_files[@]}"
  # Get the file name without the extension

  # Convert the video file to an audio file in the current directory
  ffmpeg -i $video_file -vn -acodec libmp3lame -ab 128k $file_name.mp3

  echo "Conversion of $video_file completed. The audio file is located in the current directory."

echo "All conversions completed."

Remove audio from video with ffmpeg

ffmpeg -i input.mp4 -c copy -an output.mp4
  • -i input.mp4 specifies the input video file.
  • -c copy tells FFmpeg to copy the video stream without re-encoding.
  • -an removes the audio stream from the output file.
  • output.mp4 is the name you choose for the output video file.

Reduce video size with ffmpeg

ffmpeg -i input.mp4 -c:v libx264 -crf 23 -preset medium -c:a aac -b:a 128k output.mp4
  • -i input.mp4 specifies the input video file.
  • -c:v libx264 sets the video codec to H.264, which is widely supported and provides good compression.
  • -crf 23 controls the video quality. Lower values result in higher quality but larger file sizes. A value of around 23 is a good balance between quality and size.
  • -preset medium sets the encoding speed and compression efficiency. The “medium” preset provides a good compromise.
  • -c:a aac -b:a 128k sets the audio codec to AAC with a bitrate of 128k. This ensures decent audio quality while keeping the file size reasonable.
  • output.mp4 is the name you choose for the output video file.

Create a new video from all the videos sorted by name in a folder using with ffmpeg

ffmpeg -f concat -safe 0 -i <(for f in $(ls -v /path/to/folder/*.mp4); do echo "file '$PWD/$f'"; done) -c copy output.mp4

Reduce video size for all videos in dir and sibdirs

  • Search for all videos
  • Convert
  • Set same meta data
  • Remove source video
import os
import subprocess
import sys
from datetime import datetime

def convert_to_mp4(src_file):
    new_file = os.path.splitext(src_file)[0] + '.mp4'['ffmpeg', '-i', src_file, new_file])

    # Preserve the modification date of the original file
    mod_time = os.path.getmtime(src_file)
    os.utime(new_file, (mod_time, mod_time))


def process_directory(dir_path):
    video_extensions = ['.avi', '.mov', '.wmv', '.flv', '.mkv'] # Define video file extensions

    for root, dirs, files in os.walk(dir_path):
        for file in files:
            if any(file.lower().endswith(ext) for ext in video_extensions):
                full_path = os.path.join(root, file)
                print(f'Starting path: {full_path}')
                    print(f'Processed and converted: {full_path}')
                except Exception as e:
                    print(f'Failed to convert. Error: {str(e)}')

if __name__ == "__main__":
    if len(sys.argv) > 1:
        directory_path = sys.argv[1]
        print("Please provide a directory path.")