anonradio: add ffmpeg transcode preset

Also provide token documentation and a real example.

Signed-off-by: Joseph B. Konno <thac0@tx0.org>

anonradio/transcode.bash

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: 0BSD
+
+if [ -z $1 ] || [ -z $2 ]; then
+	echo "ERROR: expecting 2 arguments: input file (1) and output file (2)"
+	exit 1
+fi
+
+FFMPEG_DATADIR="$PWD" \
+	ffmpeg -i "$1" -fpre transcode.ffpreset "$2"