MPEG Streamclip

You can use MPEG Streamclip to: open and play most movie formats including MPEG files or transport streams You can use MPEG Streamclip to: open and play most movie formats including MPEG files or transport streams; edit them with Cut, Copy, Paste, and Trim; set In/Out points and convert them into muxed or demuxed files, or export them to QuickTime, AVI, DV and MPEG-4 files with more than professional quality, so you can easily import them in a DVD authoring tool, and use them with many other applications or devices.

MPEG Streamclip is a software that allows you edit movie files.

Here are some key features of "MPEG Streamclip":
MPEG Streamclip lets you play and edit QuickTime, DV, AVI, MPEG-4, MPEG-1; MPEG-2 or VOB files or transport streams with MPEG, PCM, or AC3 audio. MPEG Streamclip can export all these formats to QuickTime, DV/DV50, AVI/DivX and MPEG-4 with high quality encoding and even uncompressed or HD video.
video conversion is performed in the YUV color space; you can choose to scale video to any frame size using a professional 2D-FIR scaler (better than bicubic) but you can also leave it unscaled. Other optional video processing features include a powerful motion-adaptive deinterlacer, a field dominance converter, a chroma reinterlacer and an option to perform interlaced scaling instead of progressive scaling. Audio can be converted to uncompressed or to IMA, AAC, mp2 or AMR using the high-quality MP1/mp2/AC3/PCM built-in decoders of MPEG Streamclip; it is also kept in perfect sync with video using a timekeeping system.
MPEG Streamclip can save edited movies as MOV files, and (when possible) as AVI or MP4 files. Edited MPEG-1 or MPEG-2 files are saved as MPEG or TS files.
MPEG Streamclip can also convert MPEG-2 transport streams into muxed MPEG-2 files, for immediate burning at full quality with most DVD authoring applications; it can also demux MPEG-1 and MPEG-2 files and transport streams with MPEG, AC3, PCM audio to M2V and AIFF (or M1A or AC3) files, for immediate burning at full quality with DVD authoring applications. A special demuxing option is available for use in QuickTime Pro: this application does not work well with M2V files, but MPEG Streamclip can write a special "unscaled" M2V file that preserves full video quality.
MPEG Streamclip can handle files and streams larger than 4 GB, split in any number of segments, or with multiple audio tracks, and can also optionally handle timecode breaks. It is compatible with MPEG-1 and MPEG-2 video, MPEG layer 1/2 (MP1/mp2) audio, AC3/A52 audio, and PCM audio.
The player included in MPEG Streamclip lets you preview the files and transport streams before doing the conversion; it also lets you visually set the In and Out points for the conversion so you can convert just the part of the file you are interested in, and also cut commercials and other unwanted parts, or edit the stream and join two streams with Cut/Copy/Paste.