Trim 1080i MPEG2 without transcoding

[bluesk1d]

I have TV episode from my TiVo that I am trying to backup to a smaller file for archiving and playing on my 360 but I am having a heck of a time. I used directshowdump to get a clean mpg file from the .tivo file. It contains an mpeg2 video stream and a 5.1 chan ac3 stream. There appears to be some kind of glitching/artifacting at the very beginning of the mpg (1 or 2 secs) that throws the A/V out of sync when I try to convert it to another format (x264/AAC - MP4 container) using meGUI. The mpg from directshowdump plays just fine but it is 5+ gigs and in 1080i. I want a smaller file with no interlacing. I simply used an AVS to drop the odd fields and resize down to 960x540, which is what I want. For some odd reason it appears the glitch at the beginning throws the synch off by a few seconds but that there is also the problem of it getting even more out of synch progressively. It appears there may be 2 problems here. I am wondering if there is a tool that can handle 1080i mpeg2 files with AC3 streams where I can simply chop off the offending part of the file at the beginning without transcoding it. Then I can go about my normal process below (any tips or tweaks in my process are also welcome). This is also my first attempt with x264 or meGUI. I used to always use wvc-1 for the 360. I'm over that.

1. Demux AC3 from trimmed mpg file with VirtualDubMod

2. Input the following avs for the video source in meGUI:
DirectShowSource("file.mpg",seekzero=false,seek=true,audio=false)
SeparateFields().SelectEven()
spline36resize(960,540)

3. Input demuxed AC3 stream as audio input in meGUI

4. Convert to mp4 with avc/aac (downmixed stereo to ensure the 360 will play it)

[Guest]

Use DGMPGDec and start your project in from the beginning as required.