On Thu, 28 Oct 2004, Dik Takken wrote:

> > 1: 50 full-resolution images per second.
> > 2: 25 full-resolution images per second.
> 
> That would be number 2 in my case :)

        Ok - good, then mpeg2enc will do all the necessary work for you.

> > In case 2, however, you've got to do the same thing people do when they
> > convert wet film material into PAL: Take all odd-numbered lines of image 1
> > (I'm deliberately avoiding "frame" here, and in point 1.) and put them into
> > the top field, then all even-numbered lines of, still, image 1, and put them
> > into the bottom field. The purists seem to prefer not to call this an
> > interlaced stream, as the fields in fact represents the same point in time.

> This is exactly what I was trying to do. To be precise, I use this command 
> to convert the images into a yuv stream:
> 
> ppmtoy4m -F 25000:1000 -I t -L

        Change that (or leave it as) "-I p"!

        Then send the data into mpeg2enc.  You will notice that mpeg2enc 
        detects the progressive format:

   INFO: [mpeg2enc] Progressive input - selecting progressive encoding.
   INFO: [mpeg2enc] Field order for input: none/progressive
   INFO: [mpeg2enc] Progressive format frames = 1

        If you have 'dvdview' 

           http://rachmaninoff.informatik.uni-mannheim.de/dvdview/

        (Note:  it has problems building with gcc 3.4.x and I have no idea
        how to placate the newer C++ compilers)

        you can run 'dvdview -v 3 file.m2v' and see:


 picture_coding_type:   P
 picture structure:     frame picture
 frame pred frame dct:  true
 progressive frame:     true

        mpeg2enc does all the work, sets the flags and everything for you.  

        Can't get much easier than that - can you? ;)

        Cheers,
        Steven Schultz



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