How to convert just top/bot field of an interlaced mpeg-2 video to mpeg-1 ?

[vahid]

I have a .m2v (or .ts) mpeg-2 video file with interlaced frames (top and bottom fields). I want to extract top field of this video and convert it to a mpeg-1 video. Is there any tool to do this automatically ?

Height of the resulting video will be half of first video height. Extraction of top field with out any distortion (like interpolation, deinterlacing) is very important for me.

Thanks
Vahid

[manono]

AviSynth:

SeparateFields()
SelectEven()

http://avisynth.org/mediawiki/SeparateFields
http://avisynth.org/mediawiki/Select#SelectEven.2FSelectOdd

However, you can't just convert a field of MPEG-2 video to MPEG-1. It'll also have to be resized before being reencoded. Why are you doing this?

[vahid]

Thanks manono. I'm doing this for my video content analysis project. I have source code of a MPEG-1 decoder in java and i'm using it for low level feature extraction from videos. My videos are in mpeg-2 (544*576) and must be converted to MPEG-1 (544*288). Up to my knowledge MPEG-1 standard can support high resolution videos in higher bit-rates than 1.5M. Isn't that ? Can this cause any degradation in video quality ?

[manono]

Maybe it doesn't have to be resized. Maybe I should have stated it'll have to be resized for the final picture to look 'normal'. Yes, MPEG-1 video supports very high resolutions and very high bitrates.

And the act of reencoding to a lossy format always causes some quality degradation that may or may not be noticeable.

[vahid]

Maybe it doesn't have to be resized. Maybe I should have stated it'll have to be resized for the final picture to look 'normal'. Yes, MPEG-1 video supports very high resolutions and very high bitrates.

And the act of reencoding to a lossy format always causes some quality degradation that may or may not be noticeable.

Thanks manono. I used tmpgenc tool to encode output of avisynth to mpeg-1. There is a negligible loss in video quality as you mentioned. The avisynth is a good tool .