mident - a wrapper for a more reliable "mplayer -identify"

mident.bash

#!/bin/bash

#####################################################
###/        \###                                    #
###  mident  ###  This is a wrapper script around   #
###\        /###  the "-identify" feature provided  #
################  by mplayer/mplayer2, similar to   #
#                 the "mplayer.sh" script that is   #
#  distributed with mplayer itself. This version    #
#  should be significantly more reliable, easier    #
#  to customize. The output is parsable by bash:    #
#                                                   #
#      eval $(mident somefile.mkv)                  #
#                                                   #
#  One change in behavior is that this script will  #
#  only process a single file at a time. This is    #
#  by design, as it would be ambiguous which file   #
#  a variale "${ID_VIDEO_CODEC}" is referencing.    #
#                                                   #
#  Any ANSI escape sequences foudn in the data we   #
#  receive from mplayer are stripped. This is done  #
#  by first searching the $PATH to see if the tool  #
#  "ansifilter" is available. Otherwise, a regexp   #
#  based fallback will be used instead, that isn't  #
#  as well-tested hand has the serious limitation   #
#  of *ONLY* filtering color codes. Fortunately,    #
#  color codes are the only ANSI escape sequence    #
#  in common use, so the fallback is usually fine.  #
#                                                   #
#  ChangeLog:                                       #
#    2012-10-10  <pdkl95@thoughtnoise.net>          #
#      - initial version created & released         #
#                                                   #
#####################################################

########################################################################
# Copyright 2012 Brent Sanders                                         #
#                                                                      #
# This program is free software: you can redistribute it and/or modify #
# it under the terms of the GNU General Public License as published by #
# the Free Software Foundation, either version 3 of the License, or    #
# (at your option) any later version, which is available in various    #
# formats at <http://www.gnu.org/licenses/gpl.html>.                   #
#                                                                      #
# This program is distributed in the hope that it will be useful,      #
# but WITHOUT ANY WARRANTY; without even the implied warranty of       #
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        #
# GNU General Public License for more details.                         #
########################################################################

if (( $# != 1 )) ; then
    echo "Usage: $(basename "$0") <file>"
    exit 1
fi

declare    mp_bin="${MPLAYER:-mplayer2}"
declare -a mp_opt=( -nomsgcolor -vo null -ao null -frames 0 )

case ${mp_mode:-verbose} in
    verbose)  mp_opt+=( -msglevel identify=6 ) ;;
    *|normal) mp_opt+=( -msglevel identify=4 ) ;;
esac

if ! command hash ansifilter 2>&- ; then
    # The external tool "ansifilter" is much more reliable,
    # but a regex fallback works for the common case of just
    # having ot filter color codes.
    #
    # NOTE: this fallback *only* strips color codes, other
    # escape codes will probably make it through!
    ansifilter() {
        sed -r "s/\x1B\[([0-9]{1,3}((;[0-9]{1,3})*)?)?[m|K]//g"
    }
fi

mp_identify() {
    echo "ID_MIDENTIFY_BIN=${mp_bin}"
    echo "ID_MIDENTIFY_OPT=${mp_opt[@]}"
    "${mp_bin}" "${mp_opt[@]}" -v "$@" 2>/dev/null
}

id_lines_only() {
    egrep '^ID_'
}

# this should make it so we can re-parse
# our output in bash with a simple:
#     eval $(midentify file.mkv)
quote_values() {
    local line
    while read -r -s line ; do
        printf "${line%%=*}=%q\n" "${line#*=}"
    done
}

# the output is sorted to make diffs of the media ID more reliable
filter_mp_output() {
    ansifilter | id_lines_only | quote_values | sort --stable
}

identify() {
    mp_identify "$@" 2>/dev/null | filter_mp_output
}

identify "${1}"