Script to generate a Podcasts/Overcast-compatible RSS feed for audio files on your own web server

make-audio-feed.sh

#!/usr/bin/env bash

# Generates an RSS feed for a list of audio files, for consumption by Overcast
# and other podcast players.
#
# Usage:   make-audio-feed TITLE BASE_URL FILE...
# Example: (cd directory && make-audio-feed 'My Audio Files' 'https://your.server/directory/' * > .feed.rss)

set -eu -o pipefail

# https://gist.github.com/cdown/1163649#gistcomment-2157284
urlencode() {
    local LANG=C i c e=''
    for ((i=0;i<${#1};i++)); do
        c=${1:$i:1}
        [[ "$c" =~ [a-zA-Z0-9/\.\~\_\-] ]] || printf -v c '%%%02X' "'$c"
        e+="$c"
    done
    echo "$e"
}

entity-escape() {
    sed 's/&/\&amp;/g; s/</\&lt;/g; s/>/\&gt;/g; s/"/\&quot;/g; s/'"'"'/\&#39;/g'
}

title=$1
shift

cat <<EOF
<?xml version="1.0" encoding="UTF-8"?>
<rss xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd" version="2.0">
    <channel>
        <title>$title</title>
        <description>$title</description>
        <link></link>
EOF

base_url=$1
shift

for f in "$@"; do
    filename="${f##*/}"
    if [[ "$filename" =~ ^[0-9]{14}- ]] ; then
        # Use the date and time in the filename if exists
        pubTimeEpoch="${filename::8} ${filename:8:6}"
    elif [[ "$filename" =~ ^[0-9]{8}- ]] ; then
        # Use the date in the filename if exists
        pubTimeEpoch="${filename::8}"
    else
        # Use the file's mtime for the pubDate
        pubTimeEpoch="@$(stat -c %Y -- "$f")"
    fi
    pubDate=$(LC_ALL=C date --date="$pubTimeEpoch" '+%a, %d %b %Y %H:%M:%S %z')
    case ${f##*.} in
        mp3)
            mime=audio/mp3
            ;;
        aac)
            mime=audio/aac
            ;;
        oga)
            mime=audio/ogg
            ;;
        ogg)
            mime=audio/ogg
            ;;
        opus)
            mime=audio/opus
            ;;
        wav)
            mime=audio/wav
            ;;
        weba)
            mime=audio/webm
            ;;
        *)
            mime=application/octet-stream
            ;;
    esac
    cat <<EOF
        <item>
            <title>$(echo -n $filename | entity-escape)</title>
            <guid>$(echo -n $filename | entity-escape)</guid>
            <enclosure url="${base_url}$(urlencode "$f" | entity-escape)" type="$mime" />
            <pubDate>$pubDate</pubDate>
        </item>
EOF
done

cat <<EOF
    </channel>
</rss>
EOF