Cut Away End Part

Trim after 30 minutes:

ffmpeg -i 1.mpeg -t 1800 -acodec copy -vcodec copy 30minvideo.mpeg

Cut Away Start

Trim before 30 minutes:

ffmpeg -i 1.mpeg -ss 1800 -acodec copy -vcodec copy pulverizer2.mpeg

(star second is 1800, and goes to end.

Stack exchange shows the timing parameters - [1]]. -ss is start second, -t is seconds of duration.
To do lossless cutting: Lossless only does muxing and demuxing - not transcoding. [2]

ffmpeg -i 1.mpeg -t 1800 -acodec copy -vcodec copy 30minvideo.mpeg