Allow converting sequences with missing frames

The ffmpeg video conversion failed previously when the source image sequence had missing frames.
This patch allows copying the last existing image for all subsequente missing frames.

Author: wgergely

bookmarks/external/ffmpeg_widget.py

@@ -165,13 +165,23 @@ def save_changes(self):
         pbar = ffmpeg.get_progress_bar(start_n, end_n)
         pbar.open()
 
-        for n in range(start_n, end_n + 1):
+        # Get all frames from first until the last frame
+        all_frames = [f'{f}'.zfill(padding) for f in range(start_n, end_n + 1)]
+        available_frames = common.is_collapsed(self._file).group(2).strip(common.SEQSTART).strip(common.SEQEND).split(',')
+        available_frames_it = (f for f in available_frames)
+
+        # Loop through all frames
+        # Note all of these frames might refer to a real file on disk, so we'll increment
+        # the available frame number as we're looping
+        _frame = available_frames[0]
+        for n, frame in enumerate(all_frames):
             pbar.setValue(n)
 
-            n = f'{n}'.zfill(padding)
-            source = f'{start_seq.group(1)}{n}{start_seq.group(3)}.{start_seq.group(4)}'
-            file_info = QtCore.QFileInfo(source)
-            destination = f'{file_info.path()}/temp_{file_info.baseName()}.jpg'
+            if frame in available_frames:
+                _frame = next(available_frames_it)
+
+            source = f'{start_seq.group(1)}{_frame}{start_seq.group(3)}.{start_seq.group(4)}'
+            destination = f'{start_seq.group(1)}{frame}{start_seq.group(3)}_ffmpegtemp.jpg'
             _destinations.append(destination)
 
             # Convert to jpeg
@@ -183,7 +193,7 @@ def save_changes(self):
         pbar.close()
 
         file_info = QtCore.QFileInfo(self._file)
-        _file = f'{file_info.path()}/temp_{file_info.baseName()}.jpg'
+        _file = f'{file_info.path()}/{file_info.baseName()}_ffmpegtemp.jpg'
 
         mov = ffmpeg.convert(
             _file,