unitproc/isAudio

   1 #!/usr/bin/env bash
   2 # Desc: Removes lines that aren't audio file paths
   3 # Usage: find . -type f | isAudio
   4 # Input: stdin
   5 # Output: stdout
   6 # Version: 0.0.1
   7 # Example: find ~/Music/ -type f | isAudio | mpv --playlist=-
   8 # Depends:
   9 #   BK-2020-03: read_stdin() 0.0.1
  10
  11 declare -a music_codecs # Array for storing valid codec names (e.g. "aac" "mp3")
  12
  13 # Adjustable parameters
  14 music_codecs=("vorbis" "aac" "mp3" "flac" "opus"); # whitelist of valid codec_names ffprobe might return
  15
  16 yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
  17 die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
  18 must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails
  19 read_stdin() {
  20     # Desc: Consumes stdin; outputs as stdout lines
  21     # Input: stdin (consumes)
  22     # Output: stdout (newline delimited)
  23     # Example: printf "foo\nbar\n" | read_stdin
  24     # Depends: GNU bash (version 5.1.16)
  25     # Version: 0.0.1
  26     local input_stdin output;
  27
  28     # Store stdin
  29     if [[ -p /dev/stdin ]]; then
  30         input_stdin="$(cat -)";
  31     fi;
  32
  33     # Store as output array elements
  34     ## Read in stdin
  35     if [[ -n $input_stdin ]]; then
  36         while read -r line; do
  37             output+=("$line");
  38         done < <(printf "%s\n" "$input_stdin");
  39     fi;
  40
  41     # Print to stdout
  42     printf "%s\n" "${output[@]}";
  43 }; # read stdin to stdout lines
  44 check_parsable_audio_ffprobe() {
  45     # Desc: Checks if ffprobe returns valid audio codec name for file
  46     # Usage: check_parsable_audio_ffprobe [path FILE]
  47     # Version: 0.0.1
  48     # Input: arg1: file path
  49     # Output: exit code 0 if returns valid codec name; 1 otherwise
  50     # Depends: ffprobe, die()
  51     local file_in ffprobe_out
  52
  53     if [[ $# -ne 1 ]]; then die "ERROR:Invalid number of args:$#"; fi;
  54
  55     file_in="$1";
  56
  57     # Check if ffprobe detects an audio stream
  58     if ffprobe -v error -select_streams a -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 "$file_in" 1>/dev/null 2>&1; then
  59         return_state="true";
  60     else
  61         return_state="false";
  62     fi;
  63
  64     # Fail if ffprobe returns no result
  65     ffprobe_out="$(ffprobe -v error -select_streams a -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 "$file_in")";
  66     if [[ -z $ffprobe_out ]]; then
  67         return_state="false";
  68     fi;
  69
  70     # Report exit code
  71     if [[ $return_state = "true" ]]; then
  72         return 0;
  73     else
  74         return 1;
  75     fi;
  76 } # Checks if file has valid codec name using ffprobe
  77 get_audio_format() {
  78     # Desc: Gets audio format of file as string
  79     # Usage: get_audio_format arg1
  80     # Depends: ffprobe
  81     # Version: 0.0.1
  82     # Input: arg1: input file path
  83     # Output: stdout (if valid audio format)
  84     #         exit code 0 if audio file; 1 otherwise
  85     # Example: get_audio_format myvideo.mp4
  86     #   Note: Would return "opus" if full ffprobe report had 'Audio: opus, 48000 Hz, stereo, fltp'
  87     # Note: Not tested with videos containing multiple video streams
  88     # Ref/Attrib: [1] https://stackoverflow.com/questions/5618363/is-there-a-way-to-use-ffmpeg-to-determine-the-encoding-of-a-file-before-transcod
  89     #             [2] https://stackoverflow.com/questions/44123532/how-to-find-out-the-file-extension-for-extracting-audio-tracks-with-ffmpeg-and-p#comment88464070_50723126
  90     local audio_format file_in;
  91     local return_state;
  92     file_in="$1";
  93
  94     # Return error exit code if not audio file
  95     ## Return error if ffprobe itself exited on error
  96     if ! ffprobe -v error -select_streams a -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 "$file_in" 1>/dev/null 2>&1; then
  97         return_state="false";
  98     fi;
  99
 100     # Get audio format
 101     audio_format="$(ffprobe -v error -select_streams a -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 "$file_in")"; # see [1]
 102
 103     ## Return error if audio format is incorrectly formatted (e.g. reject if contains spaces)
 104     pattern="^[[:alnum:]]+$"; # alphanumeric string with no spaces
 105     if [[ $audio_format =~ $pattern ]]; then
 106         return_state="true";
 107         # Report audio format
 108         echo "$audio_format";
 109     else
 110         return_state="false";
 111     fi;
 112
 113     # Report exit code
 114     if [[ $return_state = "true" ]]; then
 115         return 0;
 116     else
 117         return 1;
 118     fi;
 119 } # Get audio format as stdout
 120 checkIsInArray() {
 121     # Desc: Checks if input arg is element in array
 122     # Usage: checkIsInArray arg1 arg2
 123     # Version: 0.0.1
 124     # Input: arg1: test string
 125     #        arg2: array
 126     # Output: exit code 0 if test string is in array; 1 otherwise
 127     # Example: checkIsInArray "foo" "${myArray[@]}"
 128     # Ref/Attrib: [1] How do I check if variable is an array? https://stackoverflow.com/a/27254437
 129     #             [2] How to pass an array as function argument? https://askubuntu.com/a/674347
 130     local return_state input arg1 string_test
 131     declare -a arg2 array_test
 132     input=("$@") # See [2]
 133     arg1="${input[0]}";
 134     arg2=("${input[@]:1}");
 135     #yell "DEBUG:input:${input[@]}";
 136     #yell "DEBUG:arg1:${arg1[@]}";
 137     #yell "DEBUG:arg2:${arg2[@]}";
 138
 139     string_test="$arg1";
 140     array_test=("${arg2[@]}");
 141
 142     #yell "DEBUG:string_test:$string_test";
 143     #yell "DEBUG:$(declare -p array_test)";
 144     for element in "${array_test[@]}"; do
 145         #yell "DEBUG:element:$element";
 146         if [[ "$element" =~ ^"$string_test" ]]; then
 147             return_state="true";
 148             continue;
 149         fi;
 150     done;
 151
 152     # Report exit code
 153     if [[ $return_state == "true" ]]; then
 154         return 0;
 155     else
 156         return 1;
 157     fi;
 158 } # Check if string is element in array
 159 check_depends() {
 160     if ! command -v ffprobe 1>/dev/random 2>&1; then
 161         die "FATAL:Missing ffprobe."; fi;
 162 };
 163 main() {
 164     # Input: array: music_codecs ("mp3" "aac" ...)
 165     #        stdin
 166     # Output: stdout
 167     # Depends:
 168     #   BK-2020-03: read_stdin() 0.0.1
 169
 170     # check dependencies
 171     check_depends;
 172
 173     # iterate through stdin lines
 174     while read -r line; do
 175         # check if file
 176         if [[ ! -f $line ]]; then continue; fi; # reject
 177
 178         # check if valid codec
 179         if ! check_parsable_audio_ffprobe "$line"; then
 180             continue; fi; # reject
 181
 182         # Check if desired codec
 183         file_format="$(get_audio_format "$line")";
 184         if ! checkIsInArray "$file_format" "${music_codecs[@]}"; then
 185             continue; fi; # reject
 186
 187         # Output line to stdout
 188         printf "%s\n" "$line";
 189     done < <(read_stdin);
 190 }; # main program
 191
 192 main "$@" 2>/dev/random;
 193
 194 # Author: Steven Baltakatei Sandoval
 195 # License: GPLv3+