Re: image quality

On 25-Jun-08, at 1:41 PM, Dave McCarthy wrote:

Here is some pseudo code for an old but still-used function:

OpenMovieFile(...&movieRefNum,fsRdPerm);
NewMovieFromFile(&movie,movieRefNum,...newMovieActive,...);
CloseMovieFile(movieRefNum);

gworld = ... (allocate a gworld 1920x1080);

SetMovieGWorld(movie,gworld,NULL);
SetMovieBox(movie,&a1920x1080Rect);

for (frame = 0; frame < numFrames; ++frame)
{
movieTime = ConvertFrameToMovieTime(frame);

SetMovieTimeValue(movie,movieTime);
MoviesTask(movie,0);

// save the gworld contents somewhere
}

Now here's my issue: with certain source movies, for example one encoded with the Apple XDCAM HD 1080i60 codec, the encoded frame is 1440x1080 and QuickTime is using a not-particularly-great scaler to give the full 1920 width. The resulting gworld therefore is not as well-defined as it could be. Is there a way to tell QuickTime that I'm more interested in quality than speed for this piece of code?

Yes, assuming Apple's render actually listens to what we tell it do via track settings..

You need to walk through all the video tracks in the movie and then do the following for each video track.

theTrack = GetMovieIndTrack(thisMovie, theTrackid);

if (theTrack > -1)

SetTrackLoadSettings(theTrack,0, 0, 0,hintsHighQuality);

That sets the rendering quality to maximum.

Also to work around some bugs, it's best to call

SetMovieActive(thisMovie,false);

it right after NewMovieFromFile() and then set up the environment (i.e. SetTrackLoadSettings(), SetMovieGWorld(), SetMovieBox() etc.)

and lastly call

SetMovieActive(thisMovie,true);

which in the past forced QT to rebuild the rendering pipeline for the codec(s).

Hope That Helps..

Milton J. Aupperle

President

ASC - Aupperle Services and Contracting

Mac Software (Drivers, Components and Application) Specialist

#1005 - 815 14th Avenue. S.W.

Calgary Alberta T2R0N5

1-(403)-229-9456

email@hidden

References:
	>image quality (From: Dave McCarthy <email@hidden>)