[FFmpeg-devel] [PATCH 06/13] avformat/mxfenc: Add Sample width/height/x offset/y offset, Display x offset and F2 offset

[Tomas Härdin]

tis 2018-05-08 klockan 18:26 +0200 skrev Michael Niedermayer:
> On Tue, May 08, 2018 at 12:40:49PM +0200, Tomas Härdin wrote:
> > mån 2018-05-07 klockan 12:38 +0200 skrev Michael Niedermayer:
> > > > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > > 
> > > +    if (sc->interlaced) {
> > > +        //Display F2 Offset
> > > +        mxf_write_local_tag(pb, 4, 0x3217);
> > > +        avio_wb32(pb, -((st->codecpar->height -
> > > display_height)&1));
> > 
> > Negative values for DisplayF2Offset are not valid
> 
> The specification (SMPTE 377-1-2009) says:
> 
> The DisplayF2Offset Property adjusts the DisplayYOffset for the
> second field relative to that for the first field. Its
> value shall be zero (0) or minus 1. A value of minus 1 shall invert
> the Displayed Topness relative to the Sampled
> Topness.

Huh, the document I have is from 2004, which says "If the property is
not present, its value shall be assumed to be 0. Valid values are zero
or 1.". So I guess they changed that. I guess it's fine then.

/Tomas