[mythtv] Interlaced vs. Progressive

Isaac Richards ijr at case.edu
Mon Feb 27 16:04:33 UTC 2006

On Monday 27 February 2006 10:21, David Asher wrote:
> Ok, I spent some time looking into this yesterday.
> One call to SetVideoParams is in InitVideoCodec.  It looks like this
> would be a great place to use something other than kScan_Detect, but
> that would require decoding some video frames during init.  I started
> thinking about that and realized that there is no reason why the
> interlaced status of a video stream need be the same all the way
> through.  For instance can't an ATSC transmission switch to 480i for a
> little while and then back to 720p?  I don't think practically it
> happens with any of my stations, but I think it could.  Also certain
> DVDs are known do this, aren't they?
> So, it occurred to me that it would be better for the interlacer to be
> turned on and off in GetFrame based on the current avcodec_decode_video
> results.  Do this seem reasonable?  It looks like it would require some
> changes to how NuppelVideoPlayer handles the deinterlacer.  I wanted to
> check before trying to implement it to make sure I'm not running down
> the wrong path.

Yup, this would be better.  The only tricky bit is deciding to double the 
framerate or not if bob is being used.


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