Jerky decoding in panning scenes

[HarryAngel]

When watching movies I encoded myself, the motion gets very jerky sometimes when the camera pans around. While not being an expert in divx encoding, I understand that this is caused by too many keyframes inserted as the codec detects too many scene changes.

Are there any settings in DivX 5.0.2 which can be tweaked to address this issue? I have experimented a little with the scene change treshold setting, but without much success. But I assume I am doing something wrong, as this effect is only so extreme and annoying in movies I encode myself, while it is much less visible in other movies encoded by others (also in 5.0.2). Does it make a difference at what bitrate the movie is encoded?

I have already searched through all possible documentation but haven't found this problem mentioned. I would appreciate any hints or suggestions what I might be doing wrong or what I could do to address the problem.

[jggimi]

I've seen this symptom when post-processing is turned on during decoding. You might try turning off all post-processing options (quality level, film effect, smooth playback, double buffering, etc...) and see if that has a positive impact for you.

[Acaila]

I believe jerkiness during panning used to be a result of GMC. Don't know if they fixed it already as I never use it.

Did you use GMC on this encode? If so you might want to try again without it to see if it becomes smooth again.

[HarryAngel]

@ jggimi: I have tried I think all possible combinations of postprocessing options available, both with the original divx decoder and with ffdshow. I am quite sure it is encoding related, especially because the effect is only so annoying and noticeable in movies I encoded myself while most others play just fine with the effect only slightly visible.

@ Acaila: Thanks for the hint, I will try it out. GMC is one option I always have turned on because it is recommended in most guides and because it was my understanding that this is exactly the option that is supposed to improve these panning scenes. Is this is a known bug that it actually does the exact opposite, making it worse?

[mikeson]

http://forum.doom9.org/showthread.php?s=&threadid=26766

[divxdude]

i had some jerky motion in divx5 videos that i corrected with
larger keyframe intervals.

[theReal]

I believe jerkiness during panning used to be a result of GMC.That's interesting - I thought I had less (or none at all) jerky motion in panning scenes since I'm using GMC.
I have often noticed slightly jerky panning movements in Divx 3.11 rips, even in rather good ones (mostly downloaded, so I don't know exactly how they were done).

[DJ Alik]

I would like to reopen this discussion. Are there any ways to make the panning scenes smooth?!?

[manono]

Hi-

So none of the other suggestions mentioned above helped? Well, because the bit rate climbs during panning and scrolling scenes, if your CPU for playback is marginal to begin with, those kinds of scenes could cause it to bog down. I've experienced similar things with a 1 GHz Athlon when playing a movie with 640x480 resolution.

If you're playing off the CD-ROM, you might try and put it on the hard drive and see if it plays more smoothly

[DJ Alik]

most of the time i just copy the file directly to my hard drive first. Even the credits scroll up in a very jerky motion. And the file was encoded in 1 pass quality mode with quant = 1.9 , 702x resolution

[OvERaCiD23]

I hope you mean 704xYYY resolution; resolution multiples below 8 can lead to problems. Are you sure your source was correctly IVTC'd or simply deinterlaced? Even with something like a 900mhz (my computer), you should be able to play movies just fine. I playback movies @ 704xYYY at a desktop resolution from 640 to 1400, and my CPU usage never goes above 40%. I would look into your source video, uncheck all DivX5 post-processing options, and if that doesn't work, try ffdshow for your playback filter.

[HarryAngel]

In the meantime I know what my problem was and it had nothing to do with DivX encoding. I had all my movies muxed with AC3 audio using the standard settings in Nandub and this caused the jerky decoding (as I would have known if I had read the AC3 audio FAQ before asking the question). I am now using AVI-Mux GUI for muxing AC3 audio streams and playback is perfectly smooth now. So if your movies have AC3 audio this might be the cause of the jerky decoding, and you could try to re-mux the audio with AVI-Mux GUI.

[billou2k]

if it's even present in good encodes maybe the playback is faulty, give a try to reclock by ogo, it works well in most cases.
He realised that audio/video synchronising was quite badly done by directshow (roughly because it's based on audio rather than video) so he wrote a filter that loads everytime you want to play a video to fix that issue. a must try!

forum: http://forum.doom9.org/showthread.php?s=&threadid=39887
website: http://ogo.nerim.net/reclockfilter/
sample file to check if it works with your system: http://members.rogers.com/sagrawal1084/Panning%20Scene.avi

hope it helped.