crop start not working - timecode problem?

I have got an huge mts clip with an h264 video stream. when i put it into a project it will be played from the beginning - ignoring the crop start setting. even when i pull the play handle somewhere in the middle of the clip and press play, the video seems to start at the beginning of the clip (the play handle shows the correct position, where i dragged it before).
So i cannot select the region which should be played, only duration. i think its a problem with the timecode in the video.
i tried to put the videostream into another container (mp4, matroshka) without remuxing it, but the problem persists.

has anybody an idea how i can solve the problem without remuxing the video (loosing quality)?

Martin

Forums:

This is a problem with ffmpeg it struggles with interlaced h264. Remuxing looses no quality as you're not reencoding just taking the stream out of one container ie: MTS and putting it into another.

You could try mkvmerge rather than ffmpeg to remux.

The only open source / free solution I'm aware of is to use Avisynth with a plugin like MpegAutoIndexer it uses DGAVCDecode rather than ffmpeg. You can find the link via http://forum.doom9.org.

This will mean reencoding though to a better supported codec. ffmpeg's threaded decoding is also a problem with h264 I think so multithreaded decoding is broken too. So ffmpegs quite slow.

If you decide to transcode at high quality have a look to see what codecs may be better supported, even multithreaded.