I recently found that Xvid could do a much better job than DivX for some of my time lapses (that is, jpgs compressed to video using VirtualDub). Frustratingly, I've found it does a much worse job at others! Look at this: http://www.fys.ku.dk/~flyvholm/download/xvid.avi Patches of clouds change appearance in jerks from one frame to another. For comparison, look at the DivX output: http://www.fys.ku.dk/~flyvholm/download/divx.avi Has a bit of the same issue, but nowhere near as bad. The smaller size of the Xvid file is unrelated: I have tried with plenty of different settings, including much higher bitrate than the DivX version, but always get the same jerky patches. Is this issue inherent to Xvid, or is there some setting I haven't found which can help? Suggestions highly appreciated.
The DivX encode doesn't have any bframes. Tried re-encoding the DivX encode here using Xvid (newer build than the one you used) without bframes and it was much better. Also played a bit better (than your Xvid encode) with bframes though. One thing you might want to try is decreasing the minimum I-VOP distance. The default setting of 300 is designed for 30fps content.
Thanks for the reply. I am embarrassed to admit that the difference was not the codec. There were two issues at play, each of which managed to conceal the other during my testing: 1) Higher compression DOES cause uneven jerky appearance 2) A filter called MSU deflicker can cause it too, depending on its settings. What had me fooled was the deflicker. Due to some other artifacts I had changed a setting called 'safety'. It doesn't say if a higher or lower value is safer, but a lower value got rid of the other artifacts. Now it turns out to be responsible for these instead! Actually, using a higher value the filter does smooth out the jerky appearance and allow for higher compression (even at half file size output looks better).
