Allow non-sequential frames (empty frames)

Missing frames are allowed: they can simply mean that there is no associated
image content.

Insert empty frame (background).

diff --git a/fgen.sh b/fgen.sh
index f7015ed..7cf6abb 100755 (executable)
--- a/fgen.sh
+++ b/fgen.sh
@@ -111,6 +111,23 @@ function get_dup_to()
     echo "${token}"
 }
 
+# Arg1: start frame
+# Arg1: end frame
+function insert_empty_frames()
+{
+    local w
+    local start
+    local end
+
+    start=${1}
+    end=${2}
+
+    for w in $(seq ${start} ${end}); do
+        log_dbg "New frame ID: ${w} (empty)"
+        cp ${dest}/background.png ${dest}/${group}-f${w}.png
+    done
+}
+
 function generate_video()
 {
     if which ffmpeg 1> /dev/null 2>&1; then
@@ -283,11 +300,10 @@ if [ ${trames} -eq 1 ]; then
                 expected_nf=$((${oldnf} + 1))
 
                 if [ ${expected_nf} -ne ${nf} ]; then
-                    echo "Error: invalid frame sequence: ${nf}"
+                    echo "Warning: non-sequential frame sequence: ${nf}"
                     echo "  previous: ${oldnf}"
                     echo "  expected: ${expected_nf}"
-                    files=""
-                    continue
+                    insert_empty_frames ${expected_nf} $((${nf} -1))
                 fi
             fi