Video stuttering with B-frames or detelecine enabled

[kelledin]

Hi all,

I'm currently working through my DVD collection, and some of my DVDs are exhibiting frame stuttering at various points. So far, I've identified the following characteristics:

1) Pre-ripping the DVD to hard disk does not seem to affect this result.

2) Whenever I see this problem, the activity log also shows a lot of "MP4Mux: illegal render offset ..." messages. The converse is not true: occurrence of these messages does not guarantee that visible/obvious frame stutter occurs.

3) I can prevent this from happening (and, incidentally, get rid of the "illegal render offset" messages) by turning off B-frames. Disabling detelecine also seems to get rid of the video stutter, but does NOT get rid of the "illegal render offset" messages.

I've pastebinned a dump here for one of the problematic DVDs:

http://pastebin.com/pastebin.php?dl=m7e4312a4

Note that this is a multi-megabyte pastebin, primarily because of all the "illegal render offset" messages. I can produce more pastebins and try different settings upon request.

This is reproducible using the built-in High Profile preset with both 0.9.4 GUI and SVN r3036 GUI, using the x86-64 deb on Ubuntu 9.10. For now I'm working around it by watching for the "illegal render offset" messages, and re-doing the affected encodes with B-frames off whenever I see it crop up.

[jbrjake]

We've been seeing more of these errors lately, for several different reasons, seemingly.

What sources are you encountering this with? Can you provide very short source samples of segments that exhibit the issue?

[kelledin]

So far I've encountered it with "The Watchmen Director's Cut (2-disc Special Edition)", "Repo! The Genetic Opera", "Bangkok Dangerous", and several others.

How would you recommend grabbing short source samples, in a format most palatable by Handbrake devs? Individual .vob files hardly qualify as "very short" in my experience. My best guess would be to use mencoder to extract specific stream segments and package them raw in AVI containers, but by my understanding that's something only mplayer can swallow.

[fbacher]

I am encountering the "illegal render offset" as well. I'll work on creating a short test case. I'll work on making a VOB with the shortest segment I can create using a "binary search" method. After that I'll narrow down the options that trigger the problem. I assume you only need me to create a segment that triggers the message. This will take a few days, perhaps a week.

Update: I'm using Avidemux to edit the video down to shorter segments. Advidemux is altering the file in some way so that none of them cause the above problem. Avidemux builds an index file when I read the original in. It also adds 3 seconds to this 23 minute video. I'm not sure of the implications of this. (Yes, I believe I am using the same output format as input and MediaInfo seems to agree). I need to figure out another way to chop up the video, I'll try simple truncation.

In the encoding that fails, I see a number of "sync: video time didn't advance - dropped 1 frames" messages which I do not see in the encoding from the Advidemux produced file.

[elvisizer]

ignore me, nothing to see here . . .