can -c be made to seek?

In trying to grab a frame every 30 seconds (or every 900 frames - close enough) 
  I see tc spending time 'skipping frames' - any way to get it to seek ahead 
some number of bytes or something?  (close, even for wide values of close, would 
be fine)

Carl K

++ transcode -Q 0 -o img/x -y im -F png -x dv,null -i x.dv -c 
0-1,900-901,1800-1801,2700-2701,3600-3601
transcode v1.0.5 (C) 2001-2003 Thomas Oestreich, 2003-2004 T. Bitterberg, 
2004-2008 Transcode Team
[transcode] (probe) suggested AV correction -D 0 (0 ms) | AV 0 ms | 0 ms
[transcode] auto-probing source x.dv (ok)
[transcode] V: import format    | Digital Video  (V=dv|A=null)
[transcode] V: import frame     | 720x480  1.50:1  encoded @ 4:3
[transcode] V: bits/pixel       | 0.174
[transcode] V: decoding fps,frc | 29.970,4
[transcode] V: Y'CbCr           | YV12/I420
[transcode] A: import format    | 0x1     PCM          [48000,16,2] 1536 kbps
[transcode] A: export format    | 0x55    MPEG layer-3 [48000,16,2]  128 kbps
[transcode] V: encoding fps,frc | 29.970,4
[transcode] A: bytes per frame  | 6408 (6406.400000)
[transcode] A: adjustment       | -1600@1000
[transcode] V: IA32/AMD64 accel | sse2 (sse2 sse mmxext mmx asm C)
[transcode] V: IA32/AMD64 accel | using sse memcpy
[transcode] V: video buffer     | 10 @ 720x480
[import_null.so] v0.2.0 (2002-01-19) (video) null | (audio) null
[import_dv.so] v0.3.1 (2003-10-14) (video) DV | (audio) PCM
[export_im.so] v0.0.4 (2003-11-13) (video) *
[import_dv.so] tcextract -x dv -i "x.dv" -d 0 | tcdecode -x dv -y yv12 -d 0 -Q 5
skipping frames [000001-000899],  94.40 fps, EMT: 0:00:29, ( 0| 0| 1)
skipping frames [000901-001799],  85.14 fps, EMT: 0:01:00, ( 0| 0| 0)
skipping frames [001801-002699],  84.82 fps, EMT: 0:01:30, ( 0| 0| 2)
skipping frames [002701-003599],  92.53 fps, EMT: 0:02:00, ( 0| 0| 1)
clean up | frame threads | unload modules | cancel signal | internal threads | done
[transcode] encoded 5 frames (0 dropped, 0 cloned), clip length   0.17 s

real    0m49.181s
user    0m42.319s
sys     0m4.476s