Creating Video DVDs from mpeg-2 files: "Could not determine resulting image file size"

I seem to remember being able to select 'New DVD Project,' and simply
dragging mpegs I'd made with tovid (using 'dvd' option) onto the
video_ts folder in order to burn them onto a video dvd.

I reintalled Gentoo recently, and this now throws an error immediately
after clicking 'Brun':  "Could not determine the resulting image
size".

Here is some info about the files I'm dealing with:
$ file bf1.mpg
bf1.mpg: MPEG sequence, v2, program multiplex

Here is the debug output:
System
-----------------------
K3b Version: 1.0.5

KDE Version: 3.5.10
QT Version: 3.3.8b
Kernel: 2.6.25-gentoo-r8
Devices
-----------------------
_NEC DVD_RW ND-3550A 1.05 (/dev/hdc, ) [CD-R, CD-RW, CD-ROM, DVD-ROM,
DVD-R, DVD-RW, DVD-R DL, DVD+R, DVD+RW, DVD+R DL] [DVD-ROM, DVD-R
Sequential, DVD-R Dual Layer Sequential, DVD-RW Restricted Overwrite,
DVD-RW Sequential, DVD+RW, DVD+R, DVD+R Dual Layer, CD-ROM, CD-R,
CD-RW] [SAO, TAO, RAW, SAO/R96P, SAO/R96R, RAW/R16, RAW/R96P,
RAW/R96R, Restricted Overwrite]

_NEC DVD_RW ND-3550A 1.05 (/dev/hda, ) [CD-R, CD-RW, CD-ROM, DVD-ROM,
DVD-R, DVD-RW, DVD-R DL, DVD+R, DVD+RW, DVD+R DL] [DVD-ROM, DVD-R
Sequential, DVD-R Dual Layer Sequential, DVD-RW Restricted Overwrite,
DVD-RW Sequential, DVD+RW, DVD+R, DVD+R Dual Layer, CD-ROM, CD-R,
CD-RW] [SAO, TAO, RAW, SAO/R96R, RAW/R96R, Restricted Overwrite]
K3bIsoImager
-----------------------
mkisofs print size result: 0 (0 bytes)

Used versions
-----------------------
mkisofs: 1.1.8

mkisofs
-----------------------
/usr/bin/genisoimage: No such file or directory. Failed to open VIDEO_TS.IFO
/usr/bin/genisoimage: Can't open VMG info for '/tmp/kde-brian/k3bVideoDvd0/'.
/usr/bin/genisoimage: Unable to parse DVD-Video structures.
/usr/bin/genisoimage: Could not find correct 'VIDEO_TS' directory.
/usr/bin/genisoimage: Unable to make a DVD-Video image.
Possible reasons:
- VIDEO_TS subdirectory was not found on specified location
- VIDEO_TS has invalid contents
/usr/bin/genisoimage: No such file or directory. Failed to open VIDEO_TS.IFO
/usr/bin/genisoimage: Can't open VMG info for '/tmp/kde-brian/k3bVideoDvd0/'.
/usr/bin/genisoimage: Unable to parse DVD-Video structures.
/usr/bin/genisoimage: Could not find correct 'VIDEO_TS' directory.
Possible reasons:
- VIDEO_TS subdirectory was not found on specified location
- VIDEO_TS has invalid contents

mkisofs calculate size command:
-----------------------
/usr/bin/genisoimage -gui -graft-points -print-size -quiet -volid bf1
-volset -appid K3B THE CD KREATOR (C) 1998-2006 SEBASTIAN TRUEG AND
THE K3B TEAM -publisher -preparer -sysid LINUX -volset-size 1
-volset-seqno 1 -sort /tmp/kde-brian/k3bafGgKb.tmp -no-cache-inodes
-udf -iso-level 1 -path-list /tmp/kde-brian/k3brZrgHb.tmp -dvd-video
-f /tmp/kde-brian/k3bVideoDvd0


I see that it cannot find the .IFO file.  I feel like this was
autogenerated before, and I certainly don't remember ever needing to
make it manually before buring.

Does anyone know what's going on?

Thanks in advance

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