ffmpeg2theora segfaults on images with different size

[Bernhard M. Wiedemann]

In ffmpeg2theora-0.28 (as packaged by packman for openSUSE-11.4) I get a reproducible segfault in certain constellations with input images of different size. E.g. a single 720x400 image in a run of 800x600 images.
The same was already observed on ffmpeg2theora-0.27.

gdb ffmpeg2theora
run --inputfps 12 ppmtompg.tmp/%08d.ppm --max_size 800x600 --framerate 25 -o video/x.ogv

Input #0, image2, from 'ppmtompg.tmp/%08d.ppm':
  Duration: 00:02:25.68, start: 0.000000, bitrate: N/A
    Stream #0.0: Video: ppm, rgb24, 800x600, 25 fps, 25 tbr, 25 tbn, 25 tbc

  Resample Framerate: 12.000 => 25.000
  0:00:36.24 audio: 0kbps video: 1281kbps, ET: 00:02:21, est. size: 22.2 MB
Program received signal SIGSEGV, Segmentation fault.
rgb24ToUV_half_c (dstU=0x638180, dstV=0x6384f0, src1=<value optimized out>,
    src2=<value optimized out>, width=<value optimized out>,
    unused=<value optimized out>) at libswscale/swscale.c:1915
(gdb) bt
#0 rgb24ToUV_half_c (dstU=0x638180, dstV=0x6384f0,
    src1=<value optimized out>, src2=<value optimized out>,
    width=<value optimized out>, unused=<value optimized out>)
    at libswscale/swscale.c:1915
#1 0x00007ffff5bff9cc in hcscale (c=0x639a40, src=0x7fffffffc6a0,
    srcStride=0x7fffffffc6c0, srcSliceY=<value optimized out>,
    srcSliceH=<value optimized out>, dst=0x7fffffffc680,
    dstStride=0x7fffffffc6d0) at libswscale/swscale.c:2075
#2 swScale (c=0x639a40, src=0x7fffffffc6a0, srcStride=0x7fffffffc6c0,
    srcSliceY=<value optimized out>, srcSliceH=<value optimized out>,
    dst=0x7fffffffc680, dstStride=0x7fffffffc6d0) at libswscale/swscale.c:2350
#3 0x00007ffff5c060c9 in sws_scale (c=0x639a40, src=0x636580,
    srcStride=0x6365a0, srcSliceY=0, srcSliceH=600, dst=<value optimized out>,
    dstStride=0x636720) at libswscale/swscale_unscaled.c:793
#4 0x0000000000409223 in ff2theora_output ()
#5 0x000000000040c91d in main ()