[print_meta_field] Added documentation

[print_meta_mtag] The value for "TITLE" field now does not get inherited.

src/print_meta_field

@@ -16,5 +16,10 @@ print_meta_field() {
     local TRACK_NO="${2}"
     local FIELD="${3}"
 
-     awk -v track=${TRACK_NO} 'BEGIN {RS="\n * }"}{if(NR<=track){print $0}}' ${FILE} |  awk -v field="\"${FIELD}\"" 'BEGIN{RS="[,]?\n";FS=" : "}{if($1~field){print $2}}' | tail -n 1 | sed -e 's/^"//' -e 's/"$//'
+    # The first awk command prints out all the FIELD information for every TRACK preceeding TRACK_NO. The second
+    # awk command then keeps only the lines that match the FIELD we want, then using tail and sed, we keep only
+    # the last line (Thus the only relevant value). This permits us to use the MTAG's specs where tracks inherit
+    # the values of its previous tracks when not set. Thus, one needs only to define the ALBUM once on the first
+    # track for all other TRACKs to inherit it.
+    awk -v track=${TRACK_NO} 'BEGIN {RS="\n * }"}{if(NR<=track){print $0}}' ${FILE} |  awk -v field="\"${FIELD}\"" 'BEGIN{RS="[,]?\n";FS=" : "}{if($1~field){print $2}}' | tail -n 1 | sed -e 's/^"//' -e 's/"$//'
 }

src/print_meta_mtag

@@ -15,14 +15,21 @@
 
 print_meta_mtag() {
     local FILE=${1}
-    local TRACKNO="${2}"; shift 2
+    local TRACK_NO="${2}"; shift 2
     local tagList=(${@})
    
     [[ -z "${tagList[@]}" ]] && local tagList=($(awk 'BEGIN{RS="\",*\n * \"";FS="\" : \""}{if($1!~"@"){print $1}}' ${FILE} | awk '!seen[$0]++') IMAGEID)
 
     for tag in ${tagList[@]}; do
+        # Finalizes output with IMAGEID
         [[ "${tag}" == "IMAGEID" ]] && { echo -n "IMAGEID=$(sed 's|.tags||g' <<< $(basename "${FILE}"))"; continue; }
-        echo -n "${tag}=$(print_meta_field ${FILE} ${TRACKNO} ${tag});"
+        
+        # Skips print_meta_field for field TITLE to keep it unique. Thus, if a track
+        # does not have a defined TITLE, it won't inherit it from previous tracks
+        [[ "${tag}" == "TITLE" ]] && { [[ -z "$(awk -v track=${TRACK_NO} 'BEGIN {RS="\n * }"}{if(NR==track){print $0}}' ${FILE} |  awk -v field="\"TITLE\"" 'BEGIN{RS="[,]?\n";FS=" : "}{if($1~field){print $2}}')" ]] && continue; }
+
+        # Prints out VALUE of that TAG for that TRACK NO
+        echo -n "${tag}=$(print_meta_field ${FILE} ${TRACK_NO} ${tag});"
     done
 }