unitproc/bkt-get_audio_format

   1 #!/usr/bin/env bash
   2
   3 get_audio_format() {
   4     # Desc: Gets audio format of file as string
   5     # Usage: get_audio_format arg1
   6     # Depends: ffprobe
   7     # Version: 0.0.1
   8     # Input: arg1: input file path
   9     # Output: stdout (if valid audio format)
  10     #         exit code 0 if audio file; 1 otherwise
  11     # Example: get_audio_format myvideo.mp4
  12     #   Note: Would return "opus" if full ffprobe report had 'Audio: opus, 48000 Hz, stereo, fltp'
  13     # Note: Not tested with videos containing multiple video streams
  14     # Ref/Attrib: [1] https://stackoverflow.com/questions/5618363/is-there-a-way-to-use-ffmpeg-to-determine-the-encoding-of-a-file-before-transcod
  15     #             [2] https://stackoverflow.com/questions/44123532/how-to-find-out-the-file-extension-for-extracting-audio-tracks-with-ffmpeg-and-p#comment88464070_50723126
  16     local audio_format file_in;
  17     local return_state;
  18     file_in="$1";
  19
  20     # Return error exit code if not audio file
  21     ## Return error if ffprobe itself exited on error
  22     if ! ffprobe -v error -select_streams a -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 "$file_in" 1>/dev/null 2>&1; then
  23         return_state="false";
  24     fi;
  25
  26     # Get audio format
  27     audio_format="$(ffprobe -v error -select_streams a -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 "$file_in")"; # see [1]
  28
  29     ## Return error if audio format is incorrectly formatted (e.g. reject if contains spaces)
  30     pattern="^[[:alnum:]]+$"; # alphanumeric string with no spaces
  31     if [[ $audio_format =~ $pattern ]]; then
  32         return_state="true";
  33         # Report audio format
  34         echo "$audio_format";
  35     else
  36         return_state="false";
  37     fi;
  38
  39     # Report exit code
  40     if [[ $return_state = "true" ]]; then
  41         return 0;
  42     else
  43         return 1;
  44     fi;
  45 } # Get audio format as stdout
  46
  47 # Author: Steven Baltakatei Sandoval
  48 # License: GPLv3+