Can't "convert" (& filter) to same video format as input

[steve333]

VLC seems to be incapable of performing a "convert/save" to the same video format as the input (it just silently does nothing).
Unfortunately it seems to make the assumption that there is nothing to do if the requested output format is the same as the input, regardless of any other preferences or filters which may be selected.

There are cases when this would be very useful:
1) I would like to use VLC to re-code an inefficient MPEG2 file more efficiently (for example using the MPEG4 quantization matrix, or simply setting a lower bitrate) - without undue loss of quality.
2) I would like to use the cropp/add filter to force conversion of 4:3 MPEG2 into 16:9 MPEG2 by adding black borders (to avoid annoying default grey borders which are added by a dumb 16:9 plasma TV).

In both cases the only way I can achieve this is by converting my MPEG2 into some other format such as MPEG4 and then converting it back, which is timewasting, over-complicated and risks loss of quality.