diff --git a/workflow/process_episode.bash b/workflow/process_episode.bash
index 64c562f..9708e7f 100755
--- a/workflow/process_episode.bash
+++ b/workflow/process_episode.bash
@@ -290,6 +290,12 @@ function check_variable_is_correct() {
           echo_error "The \"license_url\" variable is missing."
         fi
       ;;
+      media)
+        if [ -z "${media}" ]
+        then
+          echo_error "The \"media\" variable is missing."
+        fi
+      ;;
       outro_flac)
         if [[ ! -d "${outro_flac}" || -z "${outro_flac}" ]]
         then
@@ -571,7 +577,7 @@ function get_episode_metadata() {
   shownotes_edited="${working_dir}/shownotes_edited.html"
 
   hostid="$( jq --raw-output '.host.Host_ID' ${shownotes_json} )"
-  host_name="$( jq --raw-output '.host.Host_Name' ${shownotes_json} )"
+  artist="$( jq --raw-output '.host.Host_Name' ${shownotes_json} )"
   email="$( jq --raw-output '.host.Host_Email' ${shownotes_json} )"
   email_padded="$( echo $email | sed 's/@/.nospam@nospam./g' )"
   title="$( jq --raw-output '.episode.Title' ${shownotes_json} )"
@@ -579,7 +585,7 @@ function get_episode_metadata() {
   series_id="$( jq --raw-output '.episode.Series' ${shownotes_json} )"
   series_name="$( jq --raw-output '.episode.Series_Name' ${shownotes_json} )"
   explicit="$( jq --raw-output '.episode.Explicit' ${shownotes_json} )"
-  episode_license="$( jq --raw-output '.episode.Show_License' ${shownotes_json} )"
+  license="$( jq --raw-output '.episode.Show_License' ${shownotes_json} )"
   ep_date="$( jq --raw-output '.metadata.Episode_Date' ${shownotes_json} )"
   ep_num="$( jq --raw-output '.metadata.Episode_Number' ${shownotes_json} )"
   key="$( jq --raw-output '.metadata.Key' ${shownotes_json} )"
@@ -604,7 +610,7 @@ function get_episode_metadata() {
   </html>'
   ) | sponge "${shownotes_html}"
 
-  episode_variables=( shownotes_json shownotes_html hostid host_name email title summary series_id series_name explicit episode_license ep_date ep_num tags host_license host_profile remote_media shownotes_json_sanatised )
+  episode_variables=( shownotes_json shownotes_html hostid artist email title summary series_id series_name explicit license ep_date ep_num tags host_license host_profile remote_media shownotes_json_sanatised )
 
   for episode_variable in "${episode_variables[@]}"
   do
@@ -932,13 +938,13 @@ function generate_initial_report() {
 </thead>
 <tbody>
 <tr><th>hostid</th><td>${hostid}</td></tr>
-<tr><th>host_name</th><td>${host_name}</td></tr>
+<tr><th>host_name</th><td>${artist}</td></tr>
 <tr><th>title</th><td>${title}</td></tr>
 <tr><th>summary</th><td>${summary}</td></tr>
 <tr><th>series_id</th><td>${series_id}</td></tr>
 <tr><th>series_name</th><td>${series_name}</td></tr>
 <tr><th>explicit</th><td>${explicit}</td></tr>
-<tr><th>episode_license</th><td>${episode_license}</td></tr>
+<tr><th>episode_license</th><td>${license}</td></tr>
 <tr><th>tags</th><td>${tags}</td></tr>
 <tr><th>host_license</th><td>${host_license}</td></tr>
 <tr><th>host_profile</th><td>${host_profile}</td></tr>
@@ -1091,10 +1097,10 @@ function post_show_to_hpr_db() {
   series_id=${series_id}
   series_name=${series_name}
   explicit=${explicit}
-  episode_license=${episode_license}
+  episode_license=${license}
   tags=${tags}
   hostid=${hostid}
-  host_name=${host_name}
+  host_name=${artist}
   host_license=${host_license}
   host_profile=${host_profile_encoded}
   notes=REMOVED"
@@ -1110,10 +1116,10 @@ function post_show_to_hpr_db() {
     \"series_id\": \"${series_id}\",
     \"series_name\": \"${series_name}\",
     \"explicit\": \"${explicit}\",
-    \"episode_license\": \"${episode_license}\",
+    \"episode_license\": \"${license}\",
     \"tags\": \"${tags}\",
     \"hostid\": \"${hostid}\",
-    \"host_name\": \"${host_name}\",
+    \"host_name\": \"${artist}\",
     \"host_license\": \"${host_license}\",
     \"host_profile\": \"${host_profile_encoded}\",
     \"notes\": \"${notes}\"
@@ -1252,6 +1258,8 @@ function generate_parent_audio() {
 function generate_derived_media() {
 
   echo_debug "Generating derived audio. generate_derived_media()"
+  
+  check_variable_is_correct media working_dir ep_num title artist license 
 
   if [[ ! -s "${working_dir}/processing/episode_final.flac" ]]
   then
@@ -1259,8 +1267,10 @@ function generate_derived_media() {
     echo_error "The final cut is not available."
   fi
 
-  episode_comment="$( jq --raw-output '.comment' "${episode_summary_json}" )"
-  episode_year="$( echo "${ep_date}" | cut -c -4 )"
+  comment="$( jq --raw-output '.comment' "${episode_summary_json}" )"
+  year="$( echo "${ep_date}" | cut -c -4 )"
+  
+  check_variable_is_correct comment year
 
   # https://wiki.multimedia.cx/index.php?title=FFmpeg_Metadata
 
@@ -1269,18 +1279,18 @@ function generate_derived_media() {
     echo_debug "Generating \"hpr${ep_num}.${extension}\"."
     ffmpeg -hide_banner -loglevel error -y -i "${working_dir}/processing/episode_final.flac" \
       -metadata title="${title}" \
-      -metadata artist="${host_name}" \
-      -metadata author="${host_name}" \
+      -metadata artist="${artist}" \
+      -metadata author="${artist}" \
       -metadata album="Hacker Public Radio" \
-      -metadata comment="${episode_comment} The license is ${episode_license}" \
-      -metadata year="${episode_year}" \
+      -metadata comment="${comment} The license is ${license}" \
+      -metadata year="${year}" \
       -metadata track="${ep_num}" \
       -metadata genre="Podcast" \
       -metadata language="English" \
-      -metadata copyright="${episode_license}" \
+      -metadata copyright="${license}" \
       "${working_dir}/hpr${ep_num}.${extension}"
 
-    fix_tags -album="Hacker Public Radio" -artist="${host_name}" -comment="${episode_comment} The license is ${episode_license}" -genre="Podcast" -title="${title}" -track="${ep_num}" -year="${episode_year}" "${working_dir}/hpr${ep_num}.${extension}"
+    fix_tags -album="Hacker Public Radio" -artist="${artist}" -comment="${comment} The license is ${license}" -genre="Podcast" -title="${title}" -track="${ep_num}" -year="${year}" "${working_dir}/hpr${ep_num}.${extension}"
 
     if [[ ! -s "${working_dir}/hpr${ep_num}.${extension}" ]]
     then
@@ -1290,12 +1300,21 @@ function generate_derived_media() {
 
   done
 
+  lengths=$( for extension in flac wav mp3 ogg opus
+  do
+    mediainfo --full --Output=XML "${working_dir}/hpr${ep_num}.${extension}" | xmlstarlet sel -T -t -m "_:MediaInfo/_:media/_:track[@type='Audio']/_:Duration[1]" -v "." -n - | awk -F '.' '{print $1}'
+  done | sort | uniq | wc -l )
+  if [ "${lengths}" -ne "1" ]
+  then
+    echo_error "The duration of the derived media is not correct."
+  fi
+
   cp -v "${media}" "${working_dir}/hpr${ep_num}_source.${media##*.}"
 
   if [[ ! -s "${working_dir}/hpr${ep_num}_source.${media##*.}" ]]
   then
-    echo_error "Failed to copy \"${working_dir}/hpr${ep_num}_source.${media##*.}\"."
     ls -al "${working_dir}/hpr${ep_num}_source.${media##*.}"
+    echo_error "Failed to copy \"${working_dir}/hpr${ep_num}_source.${media##*.}\"."
   fi
 
 }