MPEG2 TS PCR jitter

[Yates]

I am using VLC to generate MPEG TS files from DVD VOB files. I am encoding the video at bitrates between 2.5Mb and 4.5Mb and I can play the results both in VLC or multicast to several STBs. I am writing some software that analyses the TS file looking at various information within each packet. I have noticed that there seems to be a large amount of jitter in the PCR valus within the stream. If I run the same software on a DVB compliant stream I get all but no jitter in PCRs. I also noticed that there appears to be no stuffing packets in the Transport stream, this would account for the PCR jitter.
Is it possible to make VLC pad the outputted TS file to a constant bitrate? If so what is the command switch I must use?

I would be grateful for any guidance.