[PD] horizontal video lines

chris clepper cgc at humboldtblvd.com
Wed Dec 1 03:01:08 CET 2004

On Nov 30, 2004, at 2:02 PM, sara kolster wrote:

> Hi Yves and others,
> I still have problems with getting proper video output when i use the 
> firewire-camera object from PDP on OSX. Somehow there seems to be a 
> field swap problem which makes horizontal lines in the video-image. 
> Does anyone else have this problem also? And, is there something i can 
> do to fix this?

Horizontal lines like interlacing?  That would be caused by not setting 
the proper flag for QT to deliver deinterlaced progressive images.  If 
I remember correctly, this QT call does this for video input:

SGSetChannelPlayFlags(vc, channelPlayNormal);

or it could be this:

SGSetChannelPlayFlags(vc, channelPlayHighQuality);

I don't have a DV camera to test this with right now, but maybe an OSX 
GEM user can test by sending a 'quality 1' message to pix_video 
followed by a 'reset' message.  'quality 0' is  channelPlayNormal and 
'quality 1' is channelPlayHighQuality.

This is the call that does the same for movie files:

SetMoviePlayHints(m_movie, hintsHighQuality, hintsHighQuality);

You don't have to change the C code to get non-interlaced movie 
playback.  QTPro can set the appropriate flags for each file and unless 
the app overrides them, Quicktime will play them properly.

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