I know that some people here on the forum use VideoReDo to losslessly trim MPEG2 files. They have pre-released v4 which now supports h.264.
http://www.videoredo.net/msgBoard/showthread.php?t=15759
What's new in Version 4 with H.264:
This version is designed to seamlessly handle both MPEG2 and H.264 encoded files. H.264 is also called AVC and AVCHD. Technically, we support the following H.264 formats:
Input formats:
Transport streams with H.264/AVC video with the following audio codecs: MPEG Layer 2, AC-3, AAC and AAC-HE.
MP4 formatted files with H.264/AVC video with AAC and AAC-HE audio. This includes Apple MOV files, and some camera formats.
Video dimensions up to 1920x1080p at chroma 4:2:0.
All the traditional MPEG2 formats supported in earlier versions.
Output formats:
MPEG2, program, transport and dvr-ms streams with MPEG and AC-3 audio.
H.264 transport streams with MPEG Layer 2 and AAC audio. AC3 and AAC-HE audio is supported if they are present in the source file.
H.264 .MP4 files with MPEG Layer 2 and AAC audio. AAC-HE audio is suported if present in the source file.
WMV/VC1 output.
MPEG-4 Part 2 .mp4 files.
Elementary streams.
NTSC closed captioning and DVB subtitling, if present in the source, is preseved in the output file.
Smart editing:
If source and destination formats have identical formats, dimensions and bit rates, TVSuite V4 will automatically invoke its smart editing feature and not recode your source video except for a few frames at cut points. This is the traditional behavior you expected from VideoReDo in the past.
http://www.videoredo.net/msgBoard/showthread.php?t=15759
What's new in Version 4 with H.264:
This version is designed to seamlessly handle both MPEG2 and H.264 encoded files. H.264 is also called AVC and AVCHD. Technically, we support the following H.264 formats:
Input formats:
Transport streams with H.264/AVC video with the following audio codecs: MPEG Layer 2, AC-3, AAC and AAC-HE.
MP4 formatted files with H.264/AVC video with AAC and AAC-HE audio. This includes Apple MOV files, and some camera formats.
Video dimensions up to 1920x1080p at chroma 4:2:0.
All the traditional MPEG2 formats supported in earlier versions.
Output formats:
MPEG2, program, transport and dvr-ms streams with MPEG and AC-3 audio.
H.264 transport streams with MPEG Layer 2 and AAC audio. AC3 and AAC-HE audio is supported if they are present in the source file.
H.264 .MP4 files with MPEG Layer 2 and AAC audio. AAC-HE audio is suported if present in the source file.
WMV/VC1 output.
MPEG-4 Part 2 .mp4 files.
Elementary streams.
NTSC closed captioning and DVB subtitling, if present in the source, is preseved in the output file.
Smart editing:
If source and destination formats have identical formats, dimensions and bit rates, TVSuite V4 will automatically invoke its smart editing feature and not recode your source video except for a few frames at cut points. This is the traditional behavior you expected from VideoReDo in the past.