FFmpegSource2 !

[ToiletDuck]

Problem is, that at least I, after reader the specifications of transport streams, h.264, h.264, dts, ac3, etc. am not really confident in the file predictions.
An especially low bit rate encodes can have X00%+ overhead.
(for mkv&co size prediction should be nearly exact.)

FFMS  => index in file system and is bad with vc-1 and mpeg-2
LW => index in RAM, but it's bad with transportstreams and mpeg-2
DGDecNV (requires NVIDIA card)=> index in file system, but can only handle stuff the GPU can decode (next to DGDecode it's the best for anything mpeg-2 based and transportstreams)

Cu Selur

Actually, i wos talking about the difference in filesize because of the different format/container that is used.. 
Not so much about predictions in terms of Low/high bitrate compression   .

But thanks anyway,

cheers,
td