Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!snorkelwacker.mit.edu!bloom-beacon!eru!hagbard!sunic!mcsun!ukc!dcl-cs!aber-cs!gabriel!kas From: kas@cs.aber.ac.uk (Kevin Sharp) Newsgroups: comp.graphics.visualization Subject: Re: free video movies Message-ID: Date: 22 Mar 91 20:34:32 GMT References: <9103190446.AA14932@psi.rutgers.edu> Sender: kas@aber-cs.UUCP Organization: Robotics Research Group, UCW, Aberystwyth Lines: 35 In-reply-to: CDO@ibm-b.rutherford.ac.UK's message of 18 Mar 91 11:49:10 GMT >>>>> On 15 Mar 91 18:39:11 GMT Lenny Tiefel said: Lenny>How many frames per scene would be most useful? Lenny>(Assume 24 frames per second.) >>>>> On 18 Mar 91 11:49:10 GMT, CDO@ibm-b.rutherford.ac.UK (Chris Osland) said: Chris> I am intrigued that the suggestion is that of a film, not a video, Chris> frame rate. 100 frames seems fine. The frame rate should be match screen refresh rate of the monitor on which the movie is being played ie. if the refresh rate is 50Hz then the frame rate should be 50 fps, 25 fps, or 16.6 fps etc. Unfortunately there's no standard for this. UK systems are often 50Hz. US systems are usually 60Hz. Some flicker free systems offer 80Hz etc, etc, etc. Attempts at converting between frame rates are invariably unsatisfactory --- usually resulting in jerky motion. If an object based animation was used, this could be overcome. The frames can be generated at the required frame rate at `view time'. However, this is very restrictive. I suggested in my earlier posting that you should really store successive frames as `diffs'. What might work is to generate the movies at a very high frame rate. This way the `diffs' will be fairly small and the overall increase in data may be moderate. A better result should be obtained by converting from a high frame rate. -- -- Kevin Sharp, UUCP : {WALES}!ukc!aber-cs!kas Research Associate, JANET: kas@uk.ac.aber.cs AI and Robotics Research Group, PHONE: +44 970 622450 Department of Computer Science, University College of Wales, Aberystwyth, Dyfed, UK. SY23 3BZ