Fields of MPEG2 stream (top or bottom)

[alexVS]

I've read that mpeg2 contains 2 values about the fields when mpeg is interlaced.

1st value is REAL field order in mpeg,
2nd value is a flag for hardware decoder of standalone DVD player.

And these fields must be the same for correct playind on hardware players.

How can I found out what is the REAL field order of captured/ripped mpeg, and what is the value of the flag for hardware decode? With what soft?

[vlada]

You can process your video by AviSynth using AssumeTFF() and SeparateFields() filters. Then if you load this in VirtualDub, you can see if the fields are in correct order or not.
The value of interlaced flag can be read by DGIndex (part of DGMPGDec) for example. And there is also a specialised tool for this, but I don't remeber how is it called. Using it you can also change the values.

[Boulder]

Creating a DGIndex project file of the stream and then using ParseD2V on it should tell you the correct field order AFAIK.

[ronnylov]

There is one flag for field based or frame based encoding, a flag for interlaced or progressive and a flag for top or bottom field first.

The only encoder that can make field based interlaced MPEG2 I know is Canopus Procoder and the quality in this mode is very good. But field based MPEG2 may have compability problems with some DVD players.

Otherwise you normally encode interlaced as frame based, interlaced and either top or bottom field first depending of the nature of your source video. I think most capture cards record interlaced with top field first. DV is always bottom field first. You will notice if you have set the field order wrong because playback on a TV will be very jumpy. It is possible to change the field order flag after encoding with ReStream. You can also use Restream to check the setting of the field order flag in an existing MPEG2 video stream. Once you have found the correct field order for your capture device you can always use this setting because it does not change.