user/ffmpeg_parallel_encode.sh

   1 #!/bin/bash
   2 # Desc: Encodes video in parallel by processing time ranges directly from the input file.
   3 # Usage: ./ffmpeg_parallel_encode.sh input_video_file segment_duration_in_seconds
   4 # Version: 0.1.5
   5
   6 # Limit the number of parallel jobs if necessary
   7 MAX_JOBS=8;   # Adjust this number based on your system's CPU capacity
   8 MAX_MEM=512M; # Adjust this number based on your system's memory
   9
  10 set -e;  # Exit immediately if a command exits with a non-zero status
  11 set -u;  # Treat unset variables as an error
  12
  13 yell() { echo "$0: $*" >&2; }  # Print script path and all args to stderr
  14 die() { yell "$*"; exit 111; }  # Same as yell() but exits with status 111
  15 must() { "$@" || die "cannot $*"; }  # Runs command, dies if it fails
  16
  17 cleanup() {
  18     if [[ -n "${temp_dir:-}" && -d "$temp_dir" ]]; then
  19         echo "Cleaning up temporary files...";
  20         rm -rf "$temp_dir";
  21     fi
  22     if [[ -n "${temp_list_file:-}" && -f "$temp_list_file" ]]; then
  23         rm -f "$temp_list_file";
  24     fi;
  25 }; # Function to clean up temporary files
  26
  27 # Trap signals to ensure cleanup happens on script exit or interruption
  28 trap cleanup EXIT INT TERM;
  29
  30 if [[ "$#" -ne 2 ]]; then
  31     yell "Usage: $0 input_video_file segment_duration_in_seconds";
  32     exit 1;
  33 fi;
  34
  35 input_file="$1";
  36 segment_time="$2";
  37
  38 # Check if input file exists
  39 if [[ ! -f "$input_file" ]]; then
  40     die "Input file '$input_file' does not exist.";
  41 fi;
  42
  43 base_name="$(basename "$input_file" | sed 's/\.[^.]*$//')";  # Strip extension
  44 segment_prefix="${base_name}_segment";
  45 encode_suffix="_encoded";
  46 declare -a segment_filenames;
  47
  48 # Set umask to ensure files and directories are not accessible by others
  49 umask 0077;
  50
  51 # Create a unique temporary directory for encoded files in the working directory
  52 timestamp="$(date +%s)";
  53 temp_dir="$(mktemp -d "${base_name}_${timestamp}_XXXXXX")";
  54
  55 # Safety check: Ensure temp_dir is not empty and is a directory
  56 if [[ -z "${temp_dir}" || ! -d "${temp_dir}" ]]; then
  57     die "Temporary directory creation failed.";
  58 fi;
  59
  60 yell "Temporary directory created at $temp_dir";
  61
  62 # Get the total duration of the input video in seconds
  63 yell "Getting total duration of input video...";
  64 duration_str="$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$input_file")";
  65 if [[ -z "$duration_str" ]]; then
  66     die "Failed to get duration of input video.";
  67 fi;
  68
  69 duration="$(printf "%.0f" "$duration_str")";  # Convert to integer seconds
  70
  71 yell "Total duration: $duration seconds";
  72
  73 # Calculate the number of segments
  74 num_segments=$(( (duration + segment_time - 1) / segment_time ));  # Ceiling division
  75
  76 yell "Number of segments: $num_segments";
  77
  78 # Generate start times and segment filenames, write to a temporary file
  79 yell "Preparing list of start times and filenames...";
  80 temp_list_file="$(mktemp -p "$temp_dir")";
  81
  82 # Use a separator that is unlikely to appear in the data (ASCII Unit Separator)
  83 separator=$'\x1F';
  84
  85 for (( i=0; i<num_segments; i++ )); do
  86     start_time=$(( i * segment_time ));
  87     segment_filename="${segment_prefix}_$(printf "%03d" "$i")${encode_suffix}.mp4";
  88     segment_filepath="${temp_dir}/${segment_filename}";
  89     printf '%s%s%s\n' "$start_time" "$separator" "$segment_filepath" >> "$temp_list_file";
  90     segment_filenames[i]="$segment_filename";  # Store for later use
  91 done;
  92
  93 # Encode segments in parallel without writing unencoded segments to disk
  94 yell "Encoding segments in parallel...";
  95
  96 # Use GNU Parallel with the custom separator
  97 must parallel -j "$MAX_JOBS" --memsuspend "$MAX_MEM" --no-notice --bar --colsep "$separator" --arg-file "$temp_list_file" \
  98     ffmpeg -hide_banner -i "$input_file" -ss '{1}' -t "$segment_time" -c:v libx264 -preset fast -crf 23 -c:a copy '{2}';
  99
 100 # Step 3: Create a list file for concatenation
 101 segments_file="${temp_dir}/segments.txt";
 102 yell "Preparing for concatenation...";
 103 for (( i=0; i<num_segments; i++ )); do
 104     segment_filename="${segment_filenames[i]}";
 105     echo "file '$segment_filename'" >> "$segments_file";
 106 done;
 107
 108 # Safety check: Ensure segments_file is not empty
 109 if [[ ! -s "$segments_file" ]]; then
 110     die "Segments file is empty.";
 111 fi;
 112
 113 # Step 4: Concatenate the encoded segments into a single output file
 114 output_file="${base_name}_output.mp4";
 115 yell "Concatenating encoded segments into $output_file...";
 116 (
 117     cd "$temp_dir" || die "Failed to change directory to $temp_dir";
 118     must ffmpeg -f concat -safe 0 -i "segments.txt" -c copy "$output_file";
 119     mv "$output_file" ..
 120 )
 121
 122 yell "Process completed successfully in ${SECONDS} seconds. Output video is $output_file";
 123
 124 # Author: Steven Baltakatei Sandoval
 125 # License: GPLv3+