From: Gabriel G. <gab...@gm...> - 2012-02-10 18:49:47
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Record a fast bouncing ball, chances are that you will catch it in contact with the floor in *none* of the frames of the video. Where will you put the sound fx? The only way to put this kind of sound fx right is to have more than *frame* presicion! People who animate, like me, have learned this a long ago. That said I know there might be technocal problems in implementing this functionality, and I totally undestand that this could not make it into Kdenlive soon. That's perfectly ok. g 2012/2/10 Simon A. Eugster <sim...@gm...> > On 02/09/2012 04:45 AM, Brian Matherly wrote: > >> 2012/2/8 Gabriel Gazzán<gab...@gm...>: > > > >>> I think frame level accuracy is usually "not enough" precision, as also > >> > >> it is good enough for me > > > > > > It really depends on your use case. > > > > The ITU did a study and found that the threshold of detectability of lip > sync errors is about +45 ms to –125 ms (audio early to audio late) and that > the threshold of acceptability is about +90 ms to –185 ms. Apparently it is > generally more tolerable for the audio to be slightly delayed than for it > to be slightly early. > > > > > > If you only synchronize on video frame boundaries, then the worst case > scenario would be +20ms or -20ms for 25fps video (that is +/- 1/2 video > frame). The ITU research supports Dan's comment that most people can't even > detect that much error. That may be acceptable if your project will be > consumed directly. But if the output of your project is destined for > further processing (like being transcoded by another system, or being sent > through a broadcast chain), the down stream systems may add to the AV sync > error. If the error stacks up, it could exceed the thresholds of > detectability or possibly even the threshold of acceptability. > > > > So the amount of A/V error that is appropriate for your project depends > on what you plan on doing with it. > > > > ~BM > > Thanks a lot for this information! > Did they also test detectability of sync errors of hard sound effects? > Could it be lower there? > Maybe I'm a little too sensitive here, I hate watching videos in German > since they usually are badly synched (obviously ... different language) > and I often have to force myself to look somewhere else than to the > actors' faces in the first minutes. > So we could start with frame accuracy first. > Also, thanks Dan for the hints. > > Simon > > > ------------------------------------------------------------------------------ > Virtualization & Cloud Management Using Capacity Planning > Cloud computing makes use of virtualization - but cloud computing > also focuses on allowing computing to be delivered as a service. > http://www.accelacomm.com/jaw/sfnl/114/51521223/ > _______________________________________________ > Kdenlive-devel mailing list > Kde...@li... > https://lists.sourceforge.net/lists/listinfo/kdenlive-devel > |